From 1a486781d17cb2bf612c008d9450800205608bac Mon Sep 17 00:00:00 2001 From: Pol Alvarez Date: Wed, 20 May 2026 10:28:30 +0200 Subject: [PATCH 1/2] fixed await issues --- fasthtml/_modidx.py | 2 +- fasthtml/jupyter.py | 44 +- nbs/api/06_jupyter.ipynb | 2678 +++++++++++++++++++++++++++++++++++--- 3 files changed, 2517 insertions(+), 207 deletions(-) diff --git a/fasthtml/_modidx.py b/fasthtml/_modidx.py index 187bf9fa..d49e8a28 100644 --- a/fasthtml/_modidx.py +++ b/fasthtml/_modidx.py @@ -176,7 +176,6 @@ 'fasthtml.jupyter.JupyUvi._live_sse': ('api/jupyter.html#jupyuvi._live_sse', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.JupyUvi._setup_live': ('api/jupyter.html#jupyuvi._setup_live', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.JupyUvi.start': ('api/jupyter.html#jupyuvi.start', 'fasthtml/jupyter.py'), - 'fasthtml.jupyter.JupyUvi.start_async': ('api/jupyter.html#jupyuvi.start_async', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.JupyUvi.stop': ('api/jupyter.html#jupyuvi.stop', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.JupyUviAsync': ('api/jupyter.html#jupyuviasync', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.JupyUviAsync.__init__': ( 'api/jupyter.html#jupyuviasync.__init__', @@ -190,6 +189,7 @@ 'fasthtml.jupyter.render_ft': ('api/jupyter.html#render_ft', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.show': ('api/jupyter.html#show', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.wait_port_free': ('api/jupyter.html#wait_port_free', 'fasthtml/jupyter.py'), + 'fasthtml.jupyter.wait_port_free_async': ('api/jupyter.html#wait_port_free_async', 'fasthtml/jupyter.py'), 'fasthtml.jupyter.ws_client': ('api/jupyter.html#ws_client', 'fasthtml/jupyter.py')}, 'fasthtml.live_reload': {}, 'fasthtml.oauth': { 'fasthtml.oauth.AppleAppClient': ('api/oauth.html#appleappclient', 'fasthtml/oauth.py'), diff --git a/fasthtml/jupyter.py b/fasthtml/jupyter.py index 409f20ea..7ccda46f 100644 --- a/fasthtml/jupyter.py +++ b/fasthtml/jupyter.py @@ -3,8 +3,8 @@ # AUTOGENERATED! DO NOT EDIT! File to edit: ../nbs/api/06_jupyter.ipynb. # %% auto #0 -__all__ = ['nb_serve', 'nb_serve_async', 'is_port_free', 'wait_port_free', 'show', 'render_ft', 'htmx_config_port', 'JupyUvi', - 'JupyUviAsync', 'HTMX', 'ws_client'] +__all__ = ['nb_serve', 'nb_serve_async', 'is_port_free', 'wait_port_free', 'wait_port_free_async', 'show', 'render_ft', + 'htmx_config_port', 'JupyUvi', 'JupyUviAsync', 'HTMX', 'ws_client'] # %% ../nbs/api/06_jupyter.ipynb #2c69d9d0 import asyncio, socket, time, uvicorn @@ -36,23 +36,31 @@ async def nb_serve_async(app, log_level="error", port=8000, host='0.0.0.0', **kw # %% ../nbs/api/06_jupyter.ipynb #508917bc def is_port_free(port, host='localhost'): - "Check if `port` is free on `host`" - sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) + s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) + s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) try: - sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) - sock.bind((host, port)) + s.bind((host, port)) + s.listen(1) return True - except OSError: return False - finally: sock.close() + except OSError as e: return False + finally: s.close() # %% ../nbs/api/06_jupyter.ipynb #1779cb76 -def wait_port_free(port, host='localhost', max_wait=3): +def wait_port_free(port, host='localhost', max_wait=20): "Wait for `port` to be free on `host`" - start_time = time.time() - while not is_port_free(port): - if time.time() - start_time>max_wait: return print(f"Timeout") + start = time.time() + while not is_port_free(port, host): + if time.time() - start > max_wait: raise TimeoutError(f"Port {host}:{port} not free after {max_wait}s") time.sleep(0.1) +async def wait_port_free_async(port, host='localhost', max_wait=20): + "Async wait for `port` to be free on `host`" + start = time.time() + while not is_port_free(port, host): + if time.time() - start > max_wait: raise TimeoutError(f"Port {host}:{port} not free after {max_wait}s") + await asyncio.sleep(0.1) + + # %% ../nbs/api/06_jupyter.ipynb #654b36bb @delegates(_show) def show(*s, **kwargs): @@ -94,12 +102,9 @@ def __init__(self, app, log_level="error", host='0.0.0.0', port=8000, start=True def start(self): self.server = nb_serve(self.app, log_level=self.log_level, host=self.host, port=self.port,daemon=self.daemon, **self.kwargs) - async def start_async(self): - self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs) - def stop(self): self.server.should_exit = True - wait_port_free(self.port) + wait_port_free(self.port, self.host) def _setup_live(self, app): rt = self.live_rt or '/_lr' @@ -117,7 +122,7 @@ async def _live_sse(self): ver = self._live_ver yield 'data: reload\n\n' -# %% ../nbs/api/06_jupyter.ipynb #9134035e +# %% ../nbs/api/06_jupyter.ipynb #f6316c73 class JupyUviAsync(JupyUvi): "Start and stop an async Jupyter compatible uvicorn server with ASGI `app` on `port` with `log_level`" def __init__(self, app, log_level="error", host='0.0.0.0', port=8000, **kwargs): @@ -126,9 +131,10 @@ def __init__(self, app, log_level="error", host='0.0.0.0', port=8000, **kwargs): async def start(self): self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs) - def stop(self): + async def stop(self): self.server.should_exit = True - wait_port_free(self.port) + await wait_port_free_async(self.port, self.host) + # %% ../nbs/api/06_jupyter.ipynb #a448e420 from starlette.testclient import TestClient diff --git a/nbs/api/06_jupyter.ipynb b/nbs/api/06_jupyter.ipynb index c24696e1..62d26e07 100644 --- a/nbs/api/06_jupyter.ipynb +++ b/nbs/api/06_jupyter.ipynb @@ -100,14 +100,14 @@ "source": [ "#| export\n", "def is_port_free(port, host='localhost'):\n", - " \"Check if `port` is free on `host`\"\n", - " sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)\n", + " s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)\n", + " s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)\n", " try:\n", - " sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)\n", - " sock.bind((host, port))\n", + " s.bind((host, port))\n", + " s.listen(1)\n", " return True\n", - " except OSError: return False\n", - " finally: sock.close()" + " except OSError as e: return False\n", + " finally: s.close()" ] }, { @@ -118,12 +118,19 @@ "outputs": [], "source": [ "#| export\n", - "def wait_port_free(port, host='localhost', max_wait=3):\n", + "def wait_port_free(port, host='localhost', max_wait=20):\n", " \"Wait for `port` to be free on `host`\"\n", - " start_time = time.time()\n", - " while not is_port_free(port):\n", - " if time.time() - start_time>max_wait: return print(f\"Timeout\")\n", - " time.sleep(0.1)" + " start = time.time()\n", + " while not is_port_free(port, host):\n", + " if time.time() - start > max_wait: raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + " time.sleep(0.1)\n", + "\n", + "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", + " \"Async wait for `port` to be free on `host`\"\n", + " start = time.time()\n", + " while not is_port_free(port, host):\n", + " if time.time() - start > max_wait: raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + " await asyncio.sleep(0.1)\n" ] }, { @@ -206,12 +213,9 @@ " def start(self):\n", " self.server = nb_serve(self.app, log_level=self.log_level, host=self.host, port=self.port,daemon=self.daemon, **self.kwargs)\n", "\n", - " async def start_async(self):\n", - " self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs)\n", - "\n", " def stop(self):\n", " self.server.should_exit = True\n", - " wait_port_free(self.port)\n", + " wait_port_free(self.port, self.host)\n", "\n", " def _setup_live(self, app):\n", " rt = self.live_rt or '/_lr'\n", @@ -272,29 +276,9 @@ { "cell_type": "code", "execution_count": null, - "id": "0f4b31e9", + "id": "04cb3e4c", "metadata": {}, - "outputs": [ - { - "data": { - "text/html": [ - "\n", - "" - ], - "text/plain": [ - "" - ] - }, - "metadata": {}, - "output_type": "display_data" - } - ], + "outputs": [], "source": [ "app = FastHTML()\n", "rt = app.route\n", @@ -342,80 +326,42 @@ "metadata": {}, "outputs": [], "source": [ - "server.stop()\n", - "await asyncio.sleep(0.2)" + "server.stop()" ] }, { - "cell_type": "code", - "execution_count": null, - "id": "97bfb966", + "cell_type": "markdown", + "id": "d7ca5fe0", "metadata": {}, - "outputs": [ - { - "data": { - "text/html": [ - "\n", - "" - ], - "text/plain": [ - "" - ] - }, - "metadata": {}, - "output_type": "display_data" - } - ], "source": [ - "app = FastHTML()\n", - "rt = app.route\n", - "\n", - "@app.route\n", - "async def index(): return 'hi'\n", - "\n", - "server = JupyUvi(app, port=port, start=False)\n", - "await server.start_async()" + "A good way to avoid spinning up two servers when running all the notebooks cells is to check whether the `server` variable is already defined, and stop if it is the case." ] }, { "cell_type": "code", "execution_count": null, - "id": "8945d436", + "id": "470d81d0", "metadata": {}, - "outputs": [ - { - "name": "stdout", - "output_type": "stream", - "text": [ - "hi\n" - ] - } - ], + "outputs": [], "source": [ - "print((await AsyncClient().get(f'http://localhost:{port}')).text)" + "if 'server' in globals(): server.stop()\n", + "server.start()" ] }, { "cell_type": "code", "execution_count": null, - "id": "c881cfc5", + "id": "7bc1aba4", "metadata": {}, "outputs": [], "source": [ - "server.stop()\n", - "await asyncio.sleep(0.2)" + "server.stop()" ] }, { "cell_type": "code", "execution_count": null, - "id": "9134035e", + "id": "f6316c73", "metadata": {}, "outputs": [], "source": [ @@ -428,9 +374,9 @@ " async def start(self):\n", " self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs)\n", "\n", - " def stop(self):\n", + " async def stop(self):\n", " self.server.should_exit = True\n", - " wait_port_free(self.port)" + " await wait_port_free_async(self.port, self.host)\n" ] }, { @@ -438,27 +384,7 @@ "execution_count": null, "id": "959eb254", "metadata": {}, - "outputs": [ - { - "data": { - "text/html": [ - "\n", - "" - ], - "text/plain": [ - "" - ] - }, - "metadata": {}, - "output_type": "display_data" - } - ], + "outputs": [], "source": [ "server = JupyUviAsync(app, port=port)\n", "await server.start()" @@ -491,8 +417,7 @@ "metadata": {}, "outputs": [], "source": [ - "server.stop()\n", - "await asyncio.sleep(0.2)" + "await server.stop()" ] }, { @@ -540,10 +465,12 @@ "text/html": [ "\n", "\n", - "" + "" ], "text/plain": [ - "" + "HTML(\n", + "\n", + ")" ] }, "metadata": {}, @@ -568,27 +495,7 @@ "execution_count": null, "id": "78d40711", "metadata": {}, - "outputs": [ - { - "data": { - "text/html": [ - "\n", - "" - ], - "text/plain": [ - "" - ] - }, - "metadata": {}, - "output_type": "display_data" - } - ], + "outputs": [], "source": [ "server = JupyUvi(app, port=port)" ] @@ -601,13 +508,23 @@ "outputs": [ { "data": { + "text/html": [ + "
\n", + "
\n", + "
\n" + ], "text/markdown": [ - "
\n", - "
\n", - "
\n" + "
\n", + "\n", + "```html\n", + "
\n", + "\n", + "```\n", + "\n", + "
" ], "text/plain": [ - "div(('',),{'id': '_BxxYJqh2RdOaxF3FIK0VBA'})" + "
" ] }, "execution_count": null, @@ -646,13 +563,23 @@ "outputs": [ { "data": { + "text/html": [ + "
\n", + "

not loaded

\n", + "
\n" + ], "text/markdown": [ - "
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not loaded

\n", - "
\n" + "
\n", + "\n", + "```html\n", + "

not loaded

\n", + "\n", + "```\n", + "\n", + "
" ], "text/plain": [ - "p(('not loaded',),{'hx-get': ._lf object>, 'hx-trigger': 'load', 'id': '_x4TFzZPvTtWff74RmcHGVQ'})" + "

not loaded

" ] }, "execution_count": null, @@ -680,13 +607,23 @@ "outputs": [ { "data": { + "text/html": [ + "
\n", + "
\n", + "
\n" + ], "text/markdown": [ - "
\n", - "
\n", - "
\n" + "
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" ], "text/plain": [ - "div(('',),{'id': '_AsIIqL_PTs_nPASliaNYGA'})" + "
" ] }, "execution_count": null, @@ -706,13 +643,23 @@ "outputs": [ { "data": { + "text/html": [ + "
\n", + "

hi

\n", + "
\n" + ], "text/markdown": [ - "
\n", - "

hi

\n", - "
\n" + "
\n", + "\n", + "```html\n", + "

hi

\n", + "\n", + "```\n", + "\n", + "
" ], "text/plain": [ - "p(('hi',),{'hx-get': ._lf object>, 'hx-trigger': 'load', 'hx-target': '#_AsIIqL_PTs_nPASliaNYGA', 'id': '_LjH2GVPJS_6wMMIQSQpyJA'})" + "

hi

" ] }, "execution_count": null, @@ -733,8 +680,7 @@ "metadata": {}, "outputs": [], "source": [ - "server.stop()\n", - "await asyncio.sleep(0.2)" + "server.stop()" ] }, { @@ -832,30 +778,11 @@ "execution_count": null, "id": "81669294", "metadata": {}, - "outputs": [ - { - "data": { - "text/html": [ - " " - ], - "text/plain": [ - "" - ] - }, - "execution_count": null, - "metadata": {}, - "output_type": "execute_result" - } - ], + "outputs": [], "source": [ "# Run the notebook locally to see the HTMX iframe in action\n", - "HTMX()" + "# Do not commit the outputs because it will break SolveIT\n", + "# HTMX()" ] }, { @@ -903,32 +830,2409 @@ "execution_count": null, "id": "d211e8e2", "metadata": {}, - "outputs": [], + "outputs": [ + { + "name": "stderr", + "output_type": "stream", + "text": [ + "/Users/pengren/ws/nbdev/nbdev/export.py:55: UserWarning: Notebook '/Users/pengren/ws/fasthtml/nbs/api/06_jupyter_dup2.ipynb' uses `#| export` without `#| default_exp` cell.\n", + "Note nbdev2 no longer supports nbdev1 syntax. Run `nbdev-migrate` to upgrade.\n", + "See https://nbdev.fast.ai/getting_started.html for more information.\n", + " warn(f\"Notebook '{nbname}' uses `#| export` without `#| default_exp` cell.\\n\"\n" + ] + } + ], "source": [ "#| hide\n", "import nbdev; nbdev.nbdev_export()" ] }, { - "cell_type": "code", - "execution_count": null, + "cell_type": "markdown", "id": "d6eafdc3", "metadata": {}, - "outputs": [], - "source": [] - } - ], - "metadata": { - "kernelspec": { - "display_name": "python3", - "language": "python", - "name": "python3" + "source": [ + "# Discussion" + ] + }, + { + "cell_type": "markdown", + "id": "e023c62c", + "metadata": { + "solveit_ai": true + }, + "source": [ + "it seems that some server.stop have timeout in the notebook above, I have the feeling it's only for async ones, is that correct?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Not quite.\n", + "\n", + "From the notebook **the async cases are definitely a problem**, but the timeouts are **not only** on async ones.\n", + "\n", + "What the notebook shows:\n", + "\n", + "- **Sync start/stop worked once**\n", + " - `server = JupyUvi(app, port=port)`\n", + " - `server.stop()` succeeded\n", + "- **Async-start cases timed out**\n", + " - `await server.start_async()` with `JupyUvi(..., start=False)`\n", + " - `await server.start()` with `JupyUviAsync(...)`\n", + "- **A later normal `JupyUvi(...).stop()` also timed out**\n", + " - after the notebook/HTMX example\n", + "\n", + "So your feeling is **partly right, but not completely**.\n", + "\n", + "The clearest reason the **async** ones fail is this:\n", + "\n", + "- `nb_serve_async()` starts `server.serve()` on the notebook’s **current event loop**\n", + "- then `stop()` is a **sync** method that does:\n", + " - `self.server.should_exit = True`\n", + " - then busy-waits with `time.sleep(...)`\n", + "\n", + "That busy wait can block the same loop the server needs in order to actually shut down.\n", + "\n", + "So this pattern is suspicious:\n", + "\n", + "```python\n", + "self.server.should_exit = True\n", + "wait_port_free(...)\n", + "```\n", + "\n", + "inside a **synchronous** `stop()` for a server that was started with `await server.serve()` on the notebook loop.\n", + "\n", + "A good mental model is:\n", + "\n", + "- **threaded server** (`nb_serve`) → sync `stop()` can work\n", + "- **event-loop server** (`nb_serve_async`) → sync `stop()` is risky, because it blocks shutdown\n", + "\n", + "So I’d phrase the conclusion like this:\n", + "\n", + "> The async shutdown path looks like the main systematic bug, but the notebook also contains at least one timeout on a non-async `JupyUvi.stop()`, so it’s not accurate to say it’s only async.\n", + "\n", + "A likely next fix is to make the async-started server use an **async stop** too, with `await asyncio.sleep(...)` instead of `time.sleep(...)`." + ] + }, + { + "cell_type": "markdown", + "id": "64108bf8", + "metadata": { + "solveit_ai": true + }, + "source": [ + "ok, so I think we should have async wait and sync wait right? can you refactor that?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — I’d split it by **waiting style**, not by “kind of server”.\n", + "\n", + "The core idea is:\n", + "\n", + "- if shutdown is happening from normal threaded/sync code, use `time.sleep`\n", + "- if shutdown is happening on the notebook event loop, use `await asyncio.sleep`\n", + "\n", + "A clean refactor is:\n", + "\n", + "```python\n", + "def wait_port_free(port, host='localhost', max_wait=20):\n", + " \"Wait for `port` to be free on `host`\"\n", + " start = time.time()\n", + " while not is_port_free(port, host):\n", + " if time.time() - start > max_wait:\n", + " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + " time.sleep(0.1)\n", + "\n", + "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", + " \"Async wait for `port` to be free on `host`\"\n", + " start = time.time()\n", + " while not is_port_free(port, host):\n", + " if time.time() - start > max_wait:\n", + " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + " await asyncio.sleep(0.1)\n", + "```\n", + "\n", + "Then make the stop methods match the start path:\n", + "\n", + "```python\n", + "class JupyUvi:\n", + " \"Start and stop a Jupyter compatible uvicorn server with ASGI `app` on `port` with `log_level`\"\n", + " def __init__(self, app, log_level=\"error\", host='0.0.0.0', port=8000, start=True, daemon=False, **kwargs):\n", + " self.kwargs = kwargs\n", + " store_attr(but='start')\n", + " self.server = None\n", + " if start: self.start()\n", + " if not os.environ.get('IN_SOLVEIT'): htmx_config_port(port)\n", + "\n", + " def start(self):\n", + " self.server = nb_serve(self.app, log_level=self.log_level, host=self.host, port=self.port, daemon=self.daemon, **self.kwargs)\n", + "\n", + " async def start_async(self):\n", + " self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs)\n", + "\n", + " def stop(self):\n", + " self.server.should_exit = True\n", + " wait_port_free(self.port, self.host)\n", + "\n", + " async def stop_async(self):\n", + " self.server.should_exit = True\n", + " await wait_port_free_async(self.port, self.host)\n", + "```\n", + "\n", + "Then your notebook usage becomes:\n", + "\n", + "- sync/threaded server:\n", + " ```python\n", + " server = JupyUvi(app, port=port)\n", + " server.stop()\n", + " ```\n", + "\n", + "- async-started server:\n", + " ```python\n", + " server = JupyUvi(app, port=port, start=False)\n", + " await server.start_async()\n", + " await server.stop_async()\n", + " ```\n", + "\n", + "I’d also say this makes `JupyUviAsync` unnecessary unless you really want the alternate API. The main thing is: **don’t call a blocking wait from the same event loop that must perform the shutdown**." + ] + }, + { + "cell_type": "markdown", + "id": "bc8bd31c", + "metadata": { + "solveit_ai": true + }, + "source": [ + "is there a way to DRY them?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — mostly.\n", + "\n", + "The **polling logic** can be shared, but the **actual waiting** still has to differ:\n", + "\n", + "- sync path uses `time.sleep(...)`\n", + "- async path uses `await asyncio.sleep(...)`\n", + "\n", + "So the usual DRY shape is:\n", + "\n", + "1. share the **deadline / condition** logic\n", + "2. keep two tiny wrappers for the actual sleep style\n", + "\n", + "For example, conceptually:\n", + "\n", + "```python\n", + "def _port_closed(port, host): return is_port_free(port, host)\n", + "```\n", + "\n", + "then:\n", + "\n", + "```python\n", + "# sync: while not _port_closed(...): time.sleep(...)\n", + "# async: while not _port_closed(...): await asyncio.sleep(...)\n", + "```\n", + "\n", + "That’s probably the best kind of DRY here, because trying to force one function to be both sync and async usually makes the API worse, not better.\n", + "\n", + "A slightly more DRY version is to share the timeout check too:\n", + "\n", + "```python\n", + "def _check_timeout(start, host, port, max_wait):\n", + " if time.time() - start > max_wait:\n", + " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + "```\n", + "\n", + "Then both waiters become very small:\n", + "- check condition\n", + "- call `_check_timeout(...)`\n", + "- sleep in the appropriate way\n", + "\n", + "So: **yes, DRY the condition and timeout logic; keep separate sync/async wait functions**. That’s the cleanest balance." + ] }, + { + "cell_type": "markdown", + "id": "55ad622b", + "metadata": { + "solveit_ai": true + }, + "source": [ + "can you flesh out some DRY options so I see which one I like better?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — there are a few sensible levels of DRY here, and they feel quite different stylistically.\n", + "\n", + "**Option 1: Minimal DRY**\n", + "Keep two public wait functions, but share the timeout/error logic.\n", + "\n", + "```python\n", + "def _check_wait(start, host, port, max_wait):\n", + " if time.time() - start > max_wait:\n", + " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + "```\n", + "\n", + "```python\n", + "def wait_port_free(port, host='localhost', max_wait=20):\n", + " start = time.time()\n", + " while not is_port_free(port, host):\n", + " _check_wait(start, host, port, max_wait)\n", + " time.sleep(0.1)\n", + "\n", + "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", + " start = time.time()\n", + " while not is_port_free(port, host):\n", + " _check_wait(start, host, port, max_wait)\n", + " await asyncio.sleep(0.1)\n", + "```\n", + "\n", + "Why this is nice:\n", + "- very obvious\n", + "- very low cleverness\n", + "- easiest to maintain\n", + "\n", + "Why it’s not very DRY:\n", + "- loop body is still duplicated\n", + "\n", + "\n", + "**Option 2: Share the polling loop shape**\n", + "Factor out the “while condition + timeout” logic into a helper, and only vary the sleeper.\n", + "\n", + "Sync version:\n", + "\n", + "```python\n", + "def _wait_for(pred, sleep, timeout_msg, max_wait=20):\n", + " start = time.time()\n", + " while not pred():\n", + " if time.time() - start > max_wait: raise TimeoutError(timeout_msg)\n", + " sleep(0.1)\n", + "```\n", + "\n", + "Async version still needs its own helper:\n", + "\n", + "```python\n", + "async def _wait_for_async(pred, sleep, timeout_msg, max_wait=20):\n", + " start = time.time()\n", + " while not pred():\n", + " if time.time() - start > max_wait: raise TimeoutError(timeout_msg)\n", + " await sleep(0.1)\n", + "```\n", + "\n", + "Then:\n", + "\n", + "```python\n", + "def wait_port_free(port, host='localhost', max_wait=20):\n", + " return _wait_for(lambda: is_port_free(port, host), time.sleep,\n", + " f\"Port {host}:{port} not free after {max_wait}s\", max_wait)\n", + "\n", + "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", + " return await _wait_for_async(lambda: is_port_free(port, host), asyncio.sleep,\n", + " f\"Port {host}:{port} not free after {max_wait}s\", max_wait)\n", + "```\n", + "\n", + "Why this is nice:\n", + "- the public functions become tiny\n", + "- reusable for other wait conditions later\n", + "\n", + "Why it’s slightly awkward:\n", + "- you still need both `_wait_for` and `_wait_for_async`\n", + "- more abstraction than option 1\n", + "\n", + "\n", + "**Option 3: One internal async core**\n", + "Make the core waiter async, and have the sync wrapper call it in a thread or fresh loop.\n", + "\n", + "Something like:\n", + "\n", + "```python\n", + "async def _wait_port_free(port, host='localhost', max_wait=20):\n", + " start = time.time()\n", + " while not is_port_free(port, host):\n", + " if time.time() - start > max_wait:\n", + " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + " await asyncio.sleep(0.1)\n", + "```\n", + "\n", + "Then:\n", + "- `wait_port_free_async(...)` just awaits it\n", + "- `wait_port_free(...)` has to run that coroutine somehow\n", + "\n", + "Why this is nice:\n", + "- maximum logic sharing\n", + "\n", + "Why I’d be cautious:\n", + "- sync wrapper gets annoying fast\n", + "- notebook/event-loop situations are exactly where “just run the coroutine” gets fiddly\n", + "- more clever than helpful here\n", + "\n", + "\n", + "**Option 4: DRY at the stop-method level instead**\n", + "Instead of focusing on the waiters, make shutdown itself split into:\n", + "- one shared “signal shutdown”\n", + "- one sync wait\n", + "- one async wait\n", + "\n", + "For example:\n", + "\n", + "```python\n", + "def _begin_shutdown(server):\n", + " server.should_exit = True\n", + "```\n", + "\n", + "Then:\n", + "- `stop()` does `_begin_shutdown(...)` + `wait_port_free(...)`\n", + "- `stop_async()` does `_begin_shutdown(...)` + `await wait_port_free_async(...)`\n", + "\n", + "Why this is nice:\n", + "- matches the real conceptual split\n", + "- avoids over-abstracting the waiters\n", + "- probably the cleanest OO design here\n", + "\n", + "Why it’s less “pure DRY”:\n", + "- you still have two wait functions\n", + "\n", + "\n", + "My taste here:\n", + "\n", + "- **Option 1** if you want boring and robust\n", + "- **Option 4** if you want the cleanest API design\n", + "- **Option 2** if you expect to add more “wait until X” helpers later\n", + "- **Option 3** only if you really want a single core and don’t mind async/sync plumbing complexity\n", + "\n", + "If I were editing this notebook, I’d probably choose **Option 4 + Option 1**:\n", + "- shared shutdown trigger\n", + "- separate sync/async waiters\n", + "- tiny shared timeout helper\n", + "\n", + "That gives good clarity without being repetitive in the annoying parts.\n", + "\n", + "If you want, I can next write the exact refactor in the style of the current notebook — either **minimal-change**, **cleanest API**, or **most DRY**." + ] + }, + { + "cell_type": "markdown", + "id": "a5125455", + "metadata": { + "solveit_ai": true + }, + "source": [ + "what about passing the sleep method as a param?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — that can work, but only **up to a point**.\n", + "\n", + "The catch is:\n", + "\n", + "- `time.sleep` is a **normal function**\n", + "- `asyncio.sleep` is an **async function** that must be `await`ed\n", + "\n", + "So if you do this:\n", + "\n", + "```python\n", + "sleep_fn(...)\n", + "```\n", + "\n", + "that works for `time.sleep`, but not for `asyncio.sleep`.\n", + "\n", + "And if you do this:\n", + "\n", + "```python\n", + "await sleep_fn(...)\n", + "```\n", + "\n", + "that works for `asyncio.sleep`, but not for `time.sleep`.\n", + "\n", + "So passing `sleep` as a parameter is a nice DRY trick, but it **doesn't by itself remove the sync/async split**.\n", + "\n", + "The clean version is usually one of these:\n", + "\n", + "1. **Two helpers**, each taking a sleep fn\n", + " - sync helper calls `sleep_fn(dt)`\n", + " - async helper does `await sleep_fn(dt)`\n", + "\n", + "2. **One async core**\n", + " - always expects an awaitable sleeper\n", + " - sync code has to wrap `time.sleep`, which is usually a bit ugly\n", + "\n", + "So I’d say:\n", + "\n", + "> Passing the sleep method as a param is a good partial-DRY idea, but you still usually want separate sync and async wait functions.\n", + "\n", + "The smallest clean shape is probably:\n", + "\n", + "- shared timeout/check logic\n", + "- `wait_for(..., sleep_fn=time.sleep)`\n", + "- `wait_for_async(..., sleep_fn=asyncio.sleep)`\n", + "\n", + "If you want, I can sketch that exact shape in about 10 lines so you can judge whether it feels elegant or overabstracted." + ] + }, + { + "cell_type": "markdown", + "id": "a6fd6223", + "metadata": { + "solveit_ai": true + }, + "source": [ + "have a look at dialog ../../server-stop-repro did we miss any of the improvements? I never got a tiemout there, anything missing?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "I’m going to inspect that other dialog first so I can compare it against the notebook here and see whether any of the shutdown-related changes are missing.\n", + "\n", + "\n", + "
\n", + "pyrun(code='doc(load_dialog)')→'async def load_dialog(\\n src_dname:str…'\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_25xymgPGT4252rmtR16YP2fw\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"doc(load_dialog)\"\n", + " }\n", + " },\n", + " \"result\": \"async def load_dialog(\\n src_dname:str, # Dialog to load code from (path relative to solveit data dir, no .ipynb)\\n dname:str='', # Target dialog; defaults to current dialog\\n):\\n\\\"\\\"\\\"Run all code messages from `src_dname` into the target dialog's kernel and return dialog contents.\\\"\\\"\\\"\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I checked the available `load_dialog` helper first. It takes a source dialog path, runs that dialog’s code into the current kernel, and returns the dialog contents. Next I’m going to load `../../server-stop-repro` and inspect what’s in it.\n", + "\n", + "\n", + "
\n", + "pyrun(code="dlg_=await load_dialog('../../server-sto…")→'----------------------------------------…'\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_OoxLPiPQbONLF8xXzVnxX8zs\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"dlg_=await load_dialog('../../server-stop-repro')\\n(type(dlg_).__name__, getattr(dlg_, 'keys', None), len(dlg_) if hasattr(dlg_, '__len__') else None)\"\n", + " }\n", + " },\n", + " \"result\": \"---------------------------------------------------------------------------\\nNameError Traceback (most recent call last)\\nCell In[49], line 1\\n----> 1 await call_tool(pyrun, {'code': \\\"dlg_=await load_dialog('../../server-stop-repro')\\\\n(type(dlg_).__name__, getattr(dlg_, 'keys', None), len(dlg_) if hasattr(dlg_, '__len__') else None)\\\"})\\n\\nFile ~/ws/ipykernel-helper/ipykernel_helper/core.py:366, in call_tool(func, kw)\\n 364 async def call_tool(func, kw):\\n 365 \\\"Call `func(**kw)` with `coerce_inputs`\\\"\\n--> 366 return await maybe_await(func(**coerce_inputs(func, kw)))\\n\\nFile ~/ws/fastcore/fastcore/xtras.py:1057, in maybe_await(o)\\n 1055 \\\"Await `o` if needed, and return it\\\"\\n 1056 from inspect import isawaitable\\n-> 1057 return await o if isawaitable(o) else o\\n\\nFile ~/ws/safepyrun/safepyrun/core.py:340, in RunPython.__call__(self, code)\\n 338 tb = e.__traceback__\\n 339 while tb.tb_next and not tb.tb_frame.f_code.co_filename.startswith(' 340 raise e.with_traceback(tb) from None\\n\\nFile :1\\n----> 1 (type(dlg_).__name__, getattr(dlg_, 'keys', None), len(dlg_) if hasattr(dlg_, '__len__') else None)\\n\\nNameError: name 'getattr' is not defined\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I’m going to load that dialog into the current kernel and inspect its messages to compare it against this notebook’s server-stop patterns.\n", + "\n", + "\n", + "
\n", + "pyrun(code="dlg_=await load_dialog('../../server-sto…")→'----------------------------------------…'\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_seDgQKU9asBfav9M2rLmU4HI\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"dlg_=await load_dialog('../../server-stop-repro')\\n(type(dlg_).__name__, len(dlg_))\"\n", + " }\n", + " },\n", + " \"result\": \"---------------------------------------------------------------------------\\nTypeError Traceback (most recent call last)\\nCell In[50], line 1\\n----> 1 await call_tool(pyrun, {'code': \\\"dlg_=await load_dialog('../../server-stop-repro')\\\\n(type(dlg_).__name__, len(dlg_))\\\"})\\n\\nFile ~/ws/ipykernel-helper/ipykernel_helper/core.py:366, in call_tool(func, kw)\\n 364 async def call_tool(func, kw):\\n 365 \\\"Call `func(**kw)` with `coerce_inputs`\\\"\\n--> 366 return await maybe_await(func(**coerce_inputs(func, kw)))\\n\\nFile ~/ws/fastcore/fastcore/xtras.py:1057, in maybe_await(o)\\n 1055 \\\"Await `o` if needed, and return it\\\"\\n 1056 from inspect import isawaitable\\n-> 1057 return await o if isawaitable(o) else o\\n\\nFile ~/ws/safepyrun/safepyrun/core.py:340, in RunPython.__call__(self, code)\\n 338 tb = e.__traceback__\\n 339 while tb.tb_next and not tb.tb_frame.f_code.co_filename.startswith(' 340 raise e.with_traceback(tb) from None\\n\\nFile :1\\n----> 1 (type(dlg_).__name__, len(dlg_))\\n\\nTypeError: object of type 'ToolResponse' has no len()\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I’m going to inspect what `load_dialog('../../server-stop-repro')` returned, so I can read the loaded dialog content rather than guessing from the wrapper object.\n", + "\n", + "\n", + "
\n", + "pyrun(code='type(dlg_).__name__, xdir(dlg_)')→'----------------------------------------…'\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_aGxSJcAxOJHEBXoTX5xmZH0s\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"type(dlg_).__name__, xdir(dlg_)\"\n", + " }\n", + " },\n", + " \"result\": \"---------------------------------------------------------------------------\\nNameError Traceback (most recent call last)\\nCell In[51], line 1\\n----> 1 await call_tool(pyrun, {'code': 'type(dlg_).__name__, xdir(dlg_)'})\\n\\nFile ~/ws/ipykernel-helper/ipykernel_helper/core.py:366, in call_tool(func, kw)\\n 364 async def call_tool(func, kw):\\n 365 \\\"Call `func(**kw)` with `coerce_inputs`\\\"\\n--> 366 return await maybe_await(func(**coerce_inputs(func, kw)))\\n\\nFile ~/ws/fastcore/fastcore/xtras.py:1057, in maybe_await(o)\\n 1055 \\\"Await `o` if needed, and return it\\\"\\n 1056 from inspect import isawaitable\\n-> 1057 return await o if isawaitable(o) else o\\n\\nFile ~/ws/safepyrun/safepyrun/core.py:340, in RunPython.__call__(self, code)\\n 338 tb = e.__traceback__\\n 339 while tb.tb_next and not tb.tb_frame.f_code.co_filename.startswith(' 340 raise e.with_traceback(tb) from None\\n\\nFile :1\\n----> 1 (type(dlg_).__name__, xdir(dlg_))\\n\\nNameError: name 'dlg_' is not defined\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I’m going to load that dialog carefully and inspect what `load_dialog` returned, since my first probe showed it returns a `ToolResponse` wrapper rather than the dialog contents directly.\n", + "\n", + "\n", + "
\n", + "pyrun(code="dlg_=await load_dialog('../../server-sto…")→"('ToolResponse',\\n ToolResponse(content={…"\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_z35P3XNTpRNI30BS4jsg1BPI\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"dlg_=await load_dialog('../../server-stop-repro')\\ntype(dlg_).__name__, dlg_\"\n", + " }\n", + " },\n", + " \"result\": \"('ToolResponse',\\n ToolResponse(content={'_full': '{\\\"error\\\":\\\"Invalid path: ../../server-stop-repro\\\"}'}))\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I’m going to check how dialog paths are resolved, then search for `server-stop-repro` so I can compare it properly.\n", + "\n", + "\n", + "
\n", + "pyrun(code='doc(list_dialogs)')→'async def list_dialogs(\\n subpath:str=…'\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_M51G0hR1R6DYfqgEgd2Zac8c\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"doc(list_dialogs)\"\n", + " }\n", + " },\n", + " \"result\": \"async def list_dialogs(\\n subpath:str='', # Path under data root (absolute with `/`, else relative to current dialog's folder)\\n depth:int=1, # Directory depth\\n):\\n\\\"\\\"\\\"List dialogs and folders under `subpath`. Folders have `/` suffix.\\\"\\\"\\\"\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I tried loading `../../server-stop-repro`, but the tool says that path is invalid, so I don’t have the dialog contents yet. I’m going to inspect nearby dialog paths first so I can find the correct one.\n", + "\n", + "\n", + "
\n", + "pyrun(code="await list_dialogs('..', depth=3)")→"{'items': ['api/', 'api/00_core', 'api/0…"\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_AMbGfid5KMcz7niT7QQW2rM6\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"await list_dialogs('..', depth=3)\"\n", + " }\n", + " },\n", + " \"result\": \"{'items': ['api/', 'api/00_core', 'api/01_components', 'api/02_xtend', 'api/03_js', 'api/04_pico', 'api/05_svg', 'api/06_jupyter', 'api/06_jupyter_dup1', 'api/08_oauth', 'api/09_cli', 'explains/', 'explains/Stripe', 'explains/background_tasks', 'explains/explaining_xt_components', 'explains/faq', 'explains/imgs/', 'explains/minidataapi', 'explains/oauth', 'explains/routes', 'explains/websockets', 'fonts/', 'index', 'ref/', 'ref/concise_guide', 'ref/defining_xt_component', 'ref/handlers', 'ref/live_reload', 'ref/response_types', 'tutorials/', 'tutorials/by_example', 'tutorials/e2e', 'tutorials/imgs/', 'tutorials/jupyter_and_fasthtml', 'tutorials/quickstart-web-dev/', 'tutorials/quickstart_for_web_devs', 'unpublished/', 'unpublished/posts/', 'unpublished/tutorial_for_web_devs', 'unpublished/web-dev-tut/']}\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I looked one level up and a bit deeper. I can see the current notebook tree under `api/`, but there is no `server-stop-repro` there, so the relative path you gave doesn't resolve from this dialog.\n", + "\n", + "\n", + "
\n", + "pyrun(code="await list_dialogs('../..', depth=4)")→"{'items': ['demo/', 'docs/', 'examples/'…"\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_4OKJFWIQaAcWTCPitpE7hacv\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"await list_dialogs('../..', depth=4)\"\n", + " }\n", + " },\n", + " \"result\": \"{'items': ['demo/', 'docs/', 'examples/', 'fasthtml/', 'fasthtml/__pycache__/', 'nbs/', 'nbs/api/', 'nbs/api/00_core', 'nbs/api/01_components', 'nbs/api/02_xtend', 'nbs/api/03_js', 'nbs/api/04_pico', 'nbs/api/05_svg', 'nbs/api/06_jupyter', 'nbs/api/06_jupyter_dup1', 'nbs/api/08_oauth', 'nbs/api/09_cli', 'nbs/explains/', 'nbs/explains/Stripe', 'nbs/explains/background_tasks', 'nbs/explains/explaining_xt_components', 'nbs/explains/faq', 'nbs/explains/imgs/', 'nbs/explains/minidataapi', 'nbs/explains/oauth', 'nbs/explains/routes', 'nbs/explains/websockets', 'nbs/fonts/', 'nbs/index', 'nbs/ref/', 'nbs/ref/concise_guide', 'nbs/ref/defining_xt_component', 'nbs/ref/handlers', 'nbs/ref/live_reload', 'nbs/ref/response_types', 'nbs/tutorials/', 'nbs/tutorials/by_example', 'nbs/tutorials/e2e', 'nbs/tutorials/imgs/', 'nbs/tutorials/jupyter_and_fasthtml', 'nbs/tutorials/quickstart-web-dev/', 'nbs/tutorials/quickstart_for_web_devs', 'nbs/unpublished/', 'nbs/unpublished/posts/', 'nbs/unpublished/tutorial_for_web_devs', 'nbs/unpublished/web-dev-tut/', 'python_fasthtml.egg-info/', 'server-stop-repro', 'tests/', 'tools/']}\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I found the dialog path issue: `../../server-stop-repro` was invalid for `load_dialog`, but listing `../..` shows `server-stop-repro` does exist there. So the dialog is present; I just need to load it via the correct relative path from the current dialog folder.\n", + "\n", + "\n", + "
\n", + "pyrun(code="dlg_=await load_dialog('../..//server-st…")→"('ToolResponse',\\n ToolResponse(content={…"\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_bVzwr8lphMTdyraICA0vSvNy\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"dlg_=await load_dialog('../..//server-stop-repro')\\ntype(dlg_).__name__, dlg_\"\n", + " }\n", + " },\n", + " \"result\": \"('ToolResponse',\\n ToolResponse(content={'_full': '{\\\"error\\\":\\\"Invalid path: ../..//server-stop-repro\\\"}'}))\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I tried loading the dialog using the relative path you gave, but `load_dialog` rejected it as an invalid path. I then listed nearby dialogs and confirmed that a dialog named `server-stop-repro` does exist under the broader `fasthtml` area, so the issue is just the path format. Now I’m going to try loading it using an absolute-style dialog path.\n", + "\n", + "\n", + "
\n", + "pyrun(code="dlg_=await load_dialog('/ws/fasthtml/ser…")→"('ToolResponse',\\n ToolResponse(content={…"\n", + "\n", + "```json\n", + "{\n", + " \"id\": \"call_Qmm5cBEWqZJ2DNyPp8pLrwje\",\n", + " \"call\": {\n", + " \"function\": \"pyrun\",\n", + " \"arguments\": {\n", + " \"code\": \"dlg_=await load_dialog('/ws/fasthtml/server-stop-repro')\\ntype(dlg_).__name__, dlg_\"\n", + " }\n", + " },\n", + " \"result\": \"\\u2026onse',\\n ToolResponse(content={'_full': 'from fasthtml.common import *\\\\nfrom fasthtml.jupyter import *\\\\nfrom fastcore.utils import *\\\\nimport socket, time# Reproducing and fixing `JupyUvi.stop()` port races\\\\n\\\\nThis notebook shows why restarting a FastHTML/Jupyter uvicorn server can intermittently fail, and gives a small, testable fix.\\\\n\\\\nThe main issues identified and fixed are:\\\\n\\\\n1. **Wrong host in port checks** \\u2014 `JupyUvi` binds to `0.0.0.0`, but the port-free check was not using the same host, causing false \\\"port is free\\\" results.\\\\n2. **No timeout/error on `stop()`** \\u2014 The original `stop()` didn\\\\'t wait for the port to actually be released, so a restart immediately after could race with the old server still shutting down.\\\\n2. **Too-permissive port check (`SO_REUSEADDR`)** \\u2014 The original check set `SO_REUSEADDR` and only called `bind`, which can report a port as free even when a server is still winding down.\\\\n4. **No `listen()` call in port probe** \\u2014 A proper server does both `bind` and `listen`; the original check skipped `listen`, making it less representative of whether uvicorn could actually start.## 1. Stop not passing host to `wait_port_free`\\\\n\\\\n`wait_port_free` accepts a port & host, but JupyUvi.stop does not pass host along. By default `JupyUvi` binds to interface `0.0.0.0`. \\\\n\\\\nBinding to `0.0.0.0` means *listen to all IPv4 interfaces*. Binding to `localhost` means listen only on the loopback interface. \\\\n\\\\nBecause of that asymmetry `bind(\\\"0.0.0.0\\\", port)` needs the port to be available across all IPv4 interfaces, whereas `bind(\\\"localhost\\\", port)` only tests `loopback`. wait_port_free??\\\\n```python\\\\ndef wait_port_free(port, host=\\\\'localhost\\\\', max_wait=3):\\\\n \\\"Wait for `port` to be free on `host`\\\"\\\\n start_time = time.time()\\\\n while not is_port_free(port):\\\\n if time.time() - start_time>max_wait: return print(f\\\"Timeout\\\")\\\\n time.sleep(0.1)\\\\n```\\\\n\\\\n**File:** `~/ws/fasthtml/fasthtml/jupyter.py`JupyUvi??\\\\n```python\\\\nclass JupyUvi:\\\\n \\\"Start and stop a Jupyter compatible uvicorn server with ASGI `app` on `port` with `log_level`\\\"\\\\n def __init__(self, app, log_level=\\\"error\\\", host=\\\\'0.0.0.0\\\\', port=8000, start=True, daemon=False, **kwargs):\\\\n self.kwargs = kwargs\\\\n store_attr(but=\\\\'start\\\\')\\\\n self.server = None\\\\n if start: self.start()\\\\n if not os.environ.get(\\\\'IN_SOLVEIT\\\\'): htmx_config_port(port)\\\\n\\\\n def start(self):\\\\n self.server = nb_serve(self.app, log_level=self.log_level, host=self.host, port=self.port,daemon=self.daemon, **self.kwargs)\\\\n\\\\n async def start_async(self):\\\\n self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs)\\\\n\\\\n def stop(self):\\\\n self.server.should_exit = True\\\\n wait_port_free(self.port)\\\\n```\\\\n\\\\n**File:** `~/ws/fasthtml/fasthtml/jupyter.py`ip = socket.gethostbyname(socket.gethostname())\\\\ns = socket.socket(); s.bind((ip,0)); s.listen()\\\\nport = s.getsockname()[1]def ok(h):\\\\n try:\\\\n x = socket.socket(); x.bind((h,port)); x.listen(); x.close()\\\\n return True\\\\n except OSError: return False\\\\n\\\\nok(\\\"127.0.0.1\\\"), ok(\\\"0.0.0.0\\\")(False, False)In order to demonstrate we will bind a non-loopback IPv4 interface. We use the following trick to get the IP of the non-loopback (the port 80 is just used for getting the IP, not binding anything to it).t = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)\\\\nt.connect((\\\"8.8.8.8\\\", 8004))\\\\nip = t.getsockname()[0]\\\\nt.close()\\\\n\\\\nip192.168.1.131Now we bind that IP to a random port so re-running the notebook won\\\\'t get any \\\"address already in use errors\\\".s = socket.socket()\\\\ns.bind((ip, 0))\\\\ns.listen()\\\\nport = s.getsockname()[1]\\\\n\\\\nport61208def ok(h, port):\\\\n x = socket.socket()\\\\n try:\\\\n x.bind((h, port))\\\\n x.listen()\\\\n return True\\\\n except OSError:\\\\n return False\\\\n finally:\\\\n x.close()\\\\n\\\\nok(\\\"127.0.0.1\\\", port), ok(\\\"0.0.0.0\\\", port)(True, False)We can see that effectively checkin if 127.0.0.1 is free returns true, while the actual 0.0.0.0 inteface is not. This is a long way to say we need to pass the host to the `wait_port_free` from `server.stop()`.\\\\ns.close()JupyUvi.stop??\\\\n```python\\\\ndef stop(self):\\\\n self.server.should_exit = True\\\\n wait_port_free(self.port)\\\\n```\\\\n\\\\n**File:** `~/ws/fasthtml/fasthtml/jupyter.py`Is my understanding corre\\u2026\"\n", + "}\n", + "```\n", + "\n", + "
\n", + "\n", + "I looked through `server-stop-repro`.\n", + "\n", + "What it **does include**:\n", + "\n", + "- passing `self.host` into `wait_port_free(...)`\n", + "- making `wait_port_free(...)` **raise** instead of just printing\n", + "- using a **stricter** port probe: `bind + listen`, without `SO_REUSEADDR`\n", + "- increasing the wait budget\n", + "- patching `JupyUvi.stop(...)` to actually wait for shutdown\n", + "\n", + "What it **does not include**:\n", + "\n", + "- a separate **async shutdown path** like `stop_async()`\n", + "- an async waiter such as `wait_port_free_async(...)`\n", + "- any real exercise of the notebook’s **async-started** server cases\n", + "\n", + "So yes: I think the main missing improvement there is exactly the one we were just discussing — **split sync and async waiting/shutdown**.\n", + "\n", + "Why you probably **never got a timeout there**:\n", + "\n", + "- that repro is focused on the **host mismatch / false-free probe** bug\n", + "- once that is fixed, the sync restart path works much more reliably\n", + "- it doesn’t really reproduce the **async event-loop shutdown** problem from the notebook above\n", + "\n", + "There’s also one more thing I think is still missing, separate from timeout handling:\n", + "\n", + "- `nb_serve(...)` waits in\n", + " ```python\n", + " while not server.started: time.sleep(0.01)\n", + " ```\n", + " and if bind/startup fails, that can effectively **hang until interrupted**, rather than surfacing a clean startup error quickly\n", + "\n", + "So my short verdict is:\n", + "\n", + "1. **Yes, one improvement is still missing:** async stop/wait support. \n", + "2. **Probably another one too:** better handling of **startup failure** in `nb_serve` / `nb_serve_async`, so failed bind doesn’t just sit in the “wait until started” loop.\n", + "\n", + "If I rank them by importance:\n", + "\n", + "- **first missing:** `stop_async()` / async wait\n", + "- **second missing:** startup-failure detection during `start()` / `start_async()`" + ] + }, + { + "cell_type": "markdown", + "id": "77cdeaa3", + "metadata": { + "solveit_ai": true + }, + "source": [ + "but I have wait_port_free_async right? am I missing something?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — **in this notebook, you do already have `wait_port_free_async`**.\n", + "\n", + "So the missing piece is **not** the async waiter itself. The thing that still looks missing is the **API path that uses it cleanly and consistently**.\n", + "\n", + "In other words:\n", + "\n", + "- you have `wait_port_free_async(...)`\n", + "- you also made `JupyUviAsync.stop(...)` use it\n", + "- but in `server-stop-repro`, that async path was **not part of the fix being exercised**\n", + "- and the main `JupyUvi` API still has:\n", + " - `start()`\n", + " - `start_async()`\n", + " - `stop()`\n", + " - but **no matching `stop_async()`**\n", + "\n", + "So I’d separate the two questions:\n", + "\n", + "1. **Do you have an async waiter?** \n", + " Yes.\n", + "\n", + "2. **Is the API fully cleaned up around it?** \n", + " Not quite — unless you want `JupyUviAsync` to be the official async stop path.\n", + "\n", + "That’s why I was saying the likely missing improvement is less “write `wait_port_free_async`” and more:\n", + "\n", + "- either add `JupyUvi.stop_async()`\n", + "- or decide `JupyUviAsync` is the intended async API and keep that as the one true path\n", + "\n", + "My instinct is that `JupyUvi` with both `start_async()` and `stop_async()` is the tidier public API." + ] + }, + { + "cell_type": "markdown", + "id": "e885b259", + "metadata": { + "solveit_ai": true + }, + "source": [ + "no, you misunderstand, the problem is that the CURRENT notebook has timeout, but in the repro one I never hit them (although it was always sync). Is there any missing gotcha? or it's just a matter of waiting more??\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "I don’t think it’s **just** “wait more”.\n", + "\n", + "The big missing gotcha is that the repro notebook is **always sync/threaded**, but the current notebook mixes in **async-started servers** and then later keeps going. That changes the failure mode.\n", + "\n", + "What I think is happening:\n", + "\n", + "- In the repro notebook, `stop()` is only testing the **threaded/sync** path, so it never hits the “blocked event loop during shutdown” issue.\n", + "- In the current notebook, once you do `await server.start_async()`, a later **sync** wait can interfere with the same loop that needs to finish shutting the server down.\n", + "- After one of those async shutdowns times out, later cells are **not cleanly independent** anymore — a later timeout may just be fallout from an earlier stop that didn’t complete when expected.\n", + "\n", + "There’s also a second gotcha:\n", + "\n", + "- your “is the port free?” probe is checking **raw rebinding**\n", + "- but the notebook does real HTTP/browser-ish traffic\n", + "- so after shutdown you can get a short-lived socket state issue that makes the probe say “still busy” even though the server is basically done\n", + "\n", + "So my short answer is:\n", + "\n", + "- **No, I wouldn’t treat this as only a matter of increasing the timeout**\n", + "- **Yes, there is a real missing gotcha:** the repro doesn’t exercise the async shutdown path, and the current notebook’s later failures may be contaminated by earlier timed-out async stops\n", + "\n", + "If I had to rank likelihood:\n", + "\n", + "1. **Main cause:** async-started server + shutdown path mismatch \n", + "2. **Secondary cause:** stricter port probe than the real restart path needs \n", + "3. **Only third:** timeout length itself\n", + "\n", + "A very practical reading is: if the repro is sync-only, its success does **not** rule out a real bug in the current notebook." + ] + }, + { + "cell_type": "markdown", + "id": "48f9c5d0", + "metadata": { + "solveit_ai": true + }, + "source": [ + "is_port_free does not do raw rebinding, it tries to listen to the host w/ reuse.\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — good catch. My phrasing there was wrong.\n", + "\n", + "If `is_port_free` does `bind(..., reuse) + listen()`, then it is **not** just “raw rebinding”. The more accurate concern is:\n", + "\n", + "- it is a **probe with different socket options**\n", + "- so it may not match uvicorn’s real bind/shutdown behavior exactly\n", + "\n", + "So I’d narrow the possible gotchas to these:\n", + "\n", + "1. **Host mismatch** \n", + " `0.0.0.0` vs `localhost` / `127.0.0.1` can absolutely change the result.\n", + "\n", + "2. **Async shutdown mismatch** \n", + " If the server was started on the notebook event loop, a sync stop path can still be the real problem.\n", + "\n", + "3. **Probe semantics with `SO_REUSEADDR`** \n", + " Not “raw rebinding”, but still possibly **more permissive than the real server bind**.\n", + "\n", + "So no, I would **not** jump to “just wait more”. \n", + "But I also wouldn’t blame the probe in the same way I described before.\n", + "\n", + "The sharper version is:\n", + "\n", + "> if the repro is sync-only and the failing notebook includes async-started servers, then the repro may simply be missing the failure mode.\n", + "\n", + "If you want, I can do one more pass and separate:\n", + "- things the repro definitely rules out\n", + "- things it does **not** rule out." + ] + }, + { + "cell_type": "markdown", + "id": "b2426637", + "metadata": { + "solveit_ai": true + }, + "source": [ + "but there's no host mismatch right? we are sending it on the wait & is port free checks.\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — in the **current notebook**, if `stop()` is doing:\n", + "\n", + "```python\n", + "wait_port_free(self.port, self.host)\n", + "```\n", + "\n", + "and `wait_port_free()` is calling:\n", + "\n", + "```python\n", + "is_port_free(port, host)\n", + "```\n", + "\n", + "then **there is no host mismatch** in that path.\n", + "\n", + "So that possible bug is **off the table** here.\n", + "\n", + "That leaves the more likely causes as:\n", + "\n", + "- **async-started server, sync-stopped server**\n", + " - `await server.start_async()`\n", + " - then later `server.stop()`\n", + " - that’s the strongest remaining suspect\n", + "\n", + "- **fallout from an earlier failed stop**\n", + " - once one shutdown times out, later cells may be testing a dirty state rather than a fresh one\n", + "\n", + "- **possibly just too short a wait**\n", + " - but I would treat that as a **secondary** explanation, not the main one\n", + "\n", + "So the updated conclusion is:\n", + "\n", + "> for the current notebook, the timeout is probably **not** about host mismatch; it’s more likely about the **async shutdown path** being handled with the wrong kind of stop/wait.\n", + "\n", + "And specifically, these two cells are the suspicious ones:\n", + "\n", + "```python\n", + "await server.start_async()\n", + "server.stop()\n", + "```\n", + "\n", + "and later:\n", + "\n", + "```python\n", + "await server.stop()\n", + "```\n", + "\n", + "because `stop()` is still a sync method there." + ] + }, + { + "cell_type": "markdown", + "id": "95f8a399", + "metadata": { + "solveit_ai": true + }, + "source": [ + "can you make a sequence diagram with mermaid that shows:\n", + "- the jupyUvi start / stop sequence (sync)\n", + "- the jupyUvi start / stop sequence (async)\n", + "- where each thing runs (main thread, async? etc...)\n", + "- where the sleep happens\n", + "\n", + "if you find anything else relevant for me to understand this, add it. I'm generally pretty bad thinking about how sync python works specially when there's async (and in the current notebook env). The mermaid chart should be code like this:\n", + "```python\n", + "mermaid('''...''')\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "```python\n", + "mermaid('''\n", + "sequenceDiagram\n", + " participant NB as Notebook (main thread / event loop)\n", + " participant T as Background Thread (own loop)\n", + " participant UV as Uvicorn\n", + "\n", + " rect rgb(220, 240, 220)\n", + " Note over NB,UV: SYNC PATH — nb_serve + stop()\n", + " NB->>T: startthread(asyncio.run(server.serve()))\n", + " activate T\n", + " T->>UV: server.serve()\n", + " activate UV\n", + " loop time.sleep(0.01) on main thread — safe, T runs freely\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " loop time.sleep(0.1) on main thread — safe, T runs freely\n", + " NB->>NB: wait_port_free polls is_port_free\n", + " end\n", + " UV->>T: shutdown complete\n", + " deactivate UV\n", + " T-->>NB: port released\n", + " deactivate T\n", + " end\n", + "\n", + " rect rgb(255, 220, 220)\n", + " Note over NB,UV: ASYNC PATH — nb_serve_async + stop() ❌\n", + " NB->>NB: create_task(server.serve()) on notebook loop\n", + " activate UV\n", + " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " Note over NB: time.sleep(0.1) BLOCKS the event loop ❌\n", + " loop time.sleep(0.1) — loop is frozen, UV shutdown never runs\n", + " NB->>NB: wait_port_free polls is_port_free (always busy)\n", + " end\n", + " Note over NB,UV: TimeoutError after 20s — UV still running\n", + " end\n", + "\n", + " rect rgb(220, 230, 255)\n", + " Note over NB,UV: ASYNC PATH — nb_serve_async + stop_async() ✅\n", + " NB->>NB: create_task(server.serve()) on notebook loop\n", + " activate UV\n", + " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " loop await asyncio.sleep(0.1) — yields, UV shutdown runs ✅\n", + " NB->>NB: wait_port_free_async polls is_port_free\n", + " end\n", + " UV-->>NB: shutdown complete, port released\n", + " deactivate UV\n", + " end\n", + "''')\n", + "```\n", + "\n", + "The key insight is in the middle block: `time.sleep` is not \"pause and let other things run\" — in an async context it is \"freeze everything\". The event loop is a single-threaded cooperative scheduler, so if you block it with `time.sleep`, the uvicorn shutdown coroutine that needs that same loop simply never gets a turn." + ] + }, + { + "cell_type": "code", + "execution_count": null, + "id": "a85e5b49", + "metadata": {}, + "outputs": [ + { + "data": { + "text/html": [ + "
\n", + "
\n" + ], + "text/markdown": [ + "
\n", + "\n", + "```html\n", + "\n", + "```\n", + "\n", + "
" + ], + "text/plain": [ + "" + ] + }, + "execution_count": null, + "metadata": {}, + "output_type": "execute_result" + } + ], + "source": [ + "enable_mermaid()" + ] + }, + { + "cell_type": "markdown", + "id": "c414c87c", + "metadata": { + "solveit_ai": true + }, + "source": [ + "can you explain the main concepts in a glossary? like asyncio etc... I'm familiar with the original python and I want to know how this was bolted on top. Is everything async? what happens if we don't use asyncio? I am familiar with go and other languages if that helps explain it. \n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Here’s the glossary version, with the “how was this bolted onto Python?” angle.\n", + "\n", + "**Synchronous Python**\n", + "\n", + "Normal Python is synchronous by default.\n", + "\n", + "```python\n", + "x = f()\n", + "y = g()\n", + "```\n", + "\n", + "means:\n", + "\n", + "1. call `f`\n", + "2. wait until `f` fully finishes\n", + "3. call `g`\n", + "\n", + "There is no automatic concurrency. If `f()` blocks on sleep, network, file IO, etc., the current thread just waits.\n", + "\n", + "---\n", + "\n", + "**Thread**\n", + "\n", + "A thread is an OS-managed execution lane inside one Python process.\n", + "\n", + "In your sync `JupyUvi` path:\n", + "\n", + "```python\n", + "startthread(daemon=daemon)\n", + "def run_server(): asyncio.run(server.serve())\n", + "```\n", + "\n", + "you create a **background thread**. That thread runs uvicorn. The notebook/main thread can then keep doing other things.\n", + "\n", + "So even if the main thread does:\n", + "\n", + "```python\n", + "time.sleep(0.1)\n", + "```\n", + "\n", + "the server thread can still run.\n", + "\n", + "That is why sync `stop()` works for the sync/threaded server.\n", + "\n", + "---\n", + "\n", + "**GIL**\n", + "\n", + "The GIL, or Global Interpreter Lock, means only one Python thread executes Python bytecode at once in normal CPython.\n", + "\n", + "But threads are still useful for IO-bound work, because when a thread waits on sockets, sleeps, or system calls, another thread can run.\n", + "\n", + "For your case: the uvicorn thread and notebook thread can coexist well enough because most server work is IO/event-loop waiting.\n", + "\n", + "---\n", + "\n", + "**Async / asyncio**\n", + "\n", + "`asyncio` is Python’s standard async concurrency system.\n", + "\n", + "It is **not** automatic. Code only becomes async when it is written using:\n", + "\n", + "```python\n", + "async def ...\n", + "await ...\n", + "asyncio.create_task(...)\n", + "```\n", + "\n", + "Asyncio uses an **event loop**.\n", + "\n", + "Think of the event loop as a scheduler that repeatedly says:\n", + "\n", + "> Which coroutine is ready to make progress now?\n", + "\n", + "But it only works if coroutines voluntarily yield control, usually with `await`.\n", + "\n", + "---\n", + "\n", + "**Coroutine**\n", + "\n", + "An `async def` function does not run immediately when called.\n", + "\n", + "```python\n", + "async def f():\n", + " ...\n", + "\n", + "coro = f()\n", + "```\n", + "\n", + "`coro` is a coroutine object. It runs only when awaited or scheduled:\n", + "\n", + "```python\n", + "await f()\n", + "```\n", + "\n", + "or:\n", + "\n", + "```python\n", + "asyncio.create_task(f())\n", + "```\n", + "\n", + "---\n", + "\n", + "**Event loop**\n", + "\n", + "The event loop runs coroutines and callbacks.\n", + "\n", + "In a notebook environment, there is usually already an event loop running, because the kernel needs to support top-level `await`.\n", + "\n", + "So when you write:\n", + "\n", + "```python\n", + "await server.start_async()\n", + "```\n", + "\n", + "you are using the notebook’s existing event loop.\n", + "\n", + "Important: an event loop is usually single-threaded.\n", + "\n", + "That means if you block that thread with normal blocking code, async tasks on that loop cannot progress.\n", + "\n", + "---\n", + "\n", + "**`await`**\n", + "\n", + "`await` means:\n", + "\n", + "> Pause this coroutine until this awaited thing is ready, and give the event loop a chance to run other tasks.\n", + "\n", + "This is the key difference between:\n", + "\n", + "```python\n", + "time.sleep(1)\n", + "```\n", + "\n", + "and:\n", + "\n", + "```python\n", + "await asyncio.sleep(1)\n", + "```\n", + "\n", + "`time.sleep(1)` says:\n", + "\n", + "> Freeze this whole thread for 1 second.\n", + "\n", + "`await asyncio.sleep(1)` says:\n", + "\n", + "> Pause me for 1 second, but let other async tasks run meanwhile.\n", + "\n", + "In Go terms, `await asyncio.sleep(...)` is closer to a goroutine blocking in a scheduler-friendly way. `time.sleep(...)` inside the event loop is closer to blocking the OS thread that the scheduler itself needs.\n", + "\n", + "---\n", + "\n", + "**Task**\n", + "\n", + "A task is a scheduled coroutine.\n", + "\n", + "```python\n", + "asyncio.create_task(server.serve())\n", + "```\n", + "\n", + "means:\n", + "\n", + "> Put `server.serve()` on the event loop so it can run concurrently with other async code.\n", + "\n", + "But “concurrently” here means cooperative concurrency on the event loop, not a new OS thread.\n", + "\n", + "So this:\n", + "\n", + "```python\n", + "asyncio.create_task(server.serve())\n", + "time.sleep(20)\n", + "```\n", + "\n", + "is bad if both happen on the event loop thread, because the task was scheduled but never gets CPU time while `time.sleep` blocks.\n", + "\n", + "---\n", + "\n", + "**Blocking**\n", + "\n", + "Blocking means “this function does not return until some operation is done.”\n", + "\n", + "Examples:\n", + "\n", + "```python\n", + "time.sleep(1)\n", + "requests.get(...)\n", + "socket.accept()\n", + "```\n", + "\n", + "Blocking is normal in sync Python.\n", + "\n", + "Blocking is dangerous inside the event loop thread, because it prevents all async tasks on that loop from running.\n", + "\n", + "---\n", + "\n", + "**Non-blocking / async-friendly**\n", + "\n", + "Async-friendly code gives control back to the event loop while waiting:\n", + "\n", + "```python\n", + "await asyncio.sleep(1)\n", + "await client.get(...)\n", + "await queue.get()\n", + "```\n", + "\n", + "This lets other scheduled tasks continue.\n", + "\n", + "---\n", + "\n", + "**Is everything async?**\n", + "\n", + "No.\n", + "\n", + "Most Python code is still sync unless explicitly written as async.\n", + "\n", + "In your notebook you currently have both worlds:\n", + "\n", + "1. **sync/threaded server path**\n", + " ```python\n", + " nb_serve(...)\n", + " ```\n", + " starts uvicorn in another thread with its own event loop.\n", + "\n", + "2. **async notebook-loop server path**\n", + " ```python\n", + " await nb_serve_async(...)\n", + " ```\n", + " starts uvicorn as a task on the current notebook event loop.\n", + "\n", + "These are quite different architectures.\n", + "\n", + "---\n", + "\n", + "**What happens if we don’t use asyncio?**\n", + "\n", + "Then you’re in normal sync Python.\n", + "\n", + "For a server, you still need some way for the server to run while the notebook continues. Common options are:\n", + "\n", + "1. run the server in the foreground \n", + " - simple, but notebook is occupied\n", + "\n", + "2. run the server in a background thread \n", + " - what `nb_serve(...)` does\n", + "\n", + "3. run the server in a separate process \n", + " - stronger isolation, more overhead\n", + "\n", + "So if you don’t use asyncio directly, your sync `JupyUvi` path still works because it hides asyncio inside a background thread:\n", + "\n", + "```python\n", + "asyncio.run(server.serve())\n", + "```\n", + "\n", + "That creates and runs an event loop inside that background thread.\n", + "\n", + "---\n", + "\n", + "**`asyncio.run(...)`**\n", + "\n", + "This is the bridge from sync code into async code.\n", + "\n", + "```python\n", + "asyncio.run(coro())\n", + "```\n", + "\n", + "means:\n", + "\n", + "1. create a new event loop\n", + "2. run the coroutine until done\n", + "3. close the loop\n", + "\n", + "But you generally cannot call `asyncio.run(...)` from inside an already-running event loop. That is why notebooks often need special handling.\n", + "\n", + "In your sync server path, this is fine because it runs inside a new background thread.\n", + "\n", + "---\n", + "\n", + "**Notebook top-level `await`**\n", + "\n", + "Normal Python files cannot do this at top level:\n", + "\n", + "```python\n", + "await something()\n", + "```\n", + "\n", + "But notebooks can.\n", + "\n", + "That means the notebook kernel already manages an event loop for you.\n", + "\n", + "Convenient, but it also means this mistake is easy:\n", + "\n", + "```python\n", + "await server.start_async()\n", + "server.stop() # sync blocking wait\n", + "```\n", + "\n", + "because `server.stop()` blocks the same thread/event loop the server needs to shut down.\n", + "\n", + "---\n", + "\n", + "**Uvicorn / ASGI app**\n", + "\n", + "FastHTML is an ASGI web app.\n", + "\n", + "Uvicorn is an ASGI server. Internally it is async. Its main server loop is essentially async machinery handling sockets and HTTP.\n", + "\n", + "So even if you start it from sync code, uvicorn itself still runs async internally.\n", + "\n", + "The question is: **where is that async loop running?**\n", + "\n", + "- sync `nb_serve`: in a background thread\n", + "- async `nb_serve_async`: on the notebook’s event loop\n", + "\n", + "That location determines whether `time.sleep` is safe.\n", + "\n", + "---\n", + "\n", + "**Your concrete bug pattern**\n", + "\n", + "This is okay:\n", + "\n", + "```python\n", + "server = JupyUvi(app)\n", + "server.stop()\n", + "```\n", + "\n", + "because:\n", + "\n", + "- uvicorn runs in background thread\n", + "- main thread does blocking wait\n", + "- background thread still shuts down server\n", + "\n", + "This is risky/bad:\n", + "\n", + "```python\n", + "server = JupyUvi(app, start=False)\n", + "await server.start_async()\n", + "server.stop()\n", + "```\n", + "\n", + "because:\n", + "\n", + "- uvicorn runs on notebook event loop\n", + "- `server.stop()` uses blocking `time.sleep`\n", + "- event loop is blocked\n", + "- uvicorn cannot finish shutdown\n", + "- port never becomes free\n", + "- timeout\n", + "\n", + "This is the matching async version:\n", + "\n", + "```python\n", + "server = JupyUvi(app, start=False)\n", + "await server.start_async()\n", + "await server.stop_async()\n", + "```\n", + "\n", + "because:\n", + "\n", + "- uvicorn runs on notebook event loop\n", + "- `stop_async()` uses `await asyncio.sleep`\n", + "- event loop gets chances to run uvicorn shutdown\n", + "\n", + "---\n", + "\n", + "**Go comparison**\n", + "\n", + "In Go, goroutines are scheduled by the Go runtime, and blocking operations are generally integrated with the scheduler. You can often write blocking-looking code and still get efficient concurrency.\n", + "\n", + "In Python asyncio, concurrency is more explicit:\n", + "\n", + "- `async def` marks async functions\n", + "- `await` marks yield points\n", + "- blocking sync calls do not automatically become scheduler-friendly\n", + "\n", + "A Go-ish mental translation:\n", + "\n", + "| Go | Python asyncio |\n", + "|---|---|\n", + "| `go f()` | `asyncio.create_task(f())` |\n", + "| blocking channel receive | `await queue.get()` |\n", + "| `time.Sleep(...)` in goroutine | `await asyncio.sleep(...)` |\n", + "| blocking the scheduler thread | `time.sleep(...)` inside event loop |\n", + "| goroutine | coroutine/task, but more explicit/cooperative |\n", + "\n", + "Python also has real threads and processes, so asyncio is just one concurrency model, not the whole story.\n", + "\n", + "---\n", + "\n", + "**Rule of thumb for this notebook**\n", + "\n", + "Use paired APIs:\n", + "\n", + "```python\n", + "server.start()\n", + "server.stop()\n", + "```\n", + "\n", + "for sync/threaded mode.\n", + "\n", + "Use:\n", + "\n", + "```python\n", + "await server.start_async()\n", + "await server.stop_async()\n", + "```\n", + "\n", + "for notebook-event-loop async mode.\n", + "\n", + "Avoid mixing:\n", + "\n", + "```python\n", + "await server.start_async()\n", + "server.stop()\n", + "```\n", + "\n", + "That mixed mode is where your timeout makes conceptual sense." + ] + }, + { + "cell_type": "markdown", + "id": "37f05450", + "metadata": { + "solveit_ai": true + }, + "source": [ + "you are giving me too much info at once. First of all what IS a coroutine? is it just a concept? why is the event loop single-threaded?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "A **coroutine** in Python is a real runtime object, not just a concept.\n", + "\n", + "When you write:\n", + "\n", + "```python\n", + "async def f(): ...\n", + "```\n", + "\n", + "calling `f()` does **not** run the function body. It creates a coroutine object: a paused computation that knows “when someone awaits/schedules me, start running here.”\n", + "\n", + "Example:\n", + "\n", + "```python\n", + "c = f() # creates coroutine object\n", + "await c # actually runs it\n", + "```\n", + "\n", + "So a coroutine is like a function call that can be **paused and resumed**.\n", + "\n", + "The pause points are `await`s. At an `await`, the coroutine says to the event loop:\n", + "\n", + "> I’m waiting for something; you can run other coroutines meanwhile.\n", + "\n", + "About the event loop being single-threaded: that’s mostly a design choice for simplicity and predictability.\n", + "\n", + "A Python asyncio event loop usually runs in **one OS thread** and manages many coroutines by switching between them only at `await` points. This avoids many classic thread problems:\n", + "\n", + "- no two coroutines unexpectedly modify the same object at the exact same time\n", + "- switching happens at explicit `await` points\n", + "- less locking is needed\n", + "\n", + "So the model is:\n", + "\n", + "```text\n", + "one thread\n", + "one event loop\n", + "many paused/resumable coroutines\n", + "```\n", + "\n", + "It’s not that async *must* be single-threaded in all possible systems. It’s that Python’s `asyncio` model is mainly **cooperative multitasking inside one thread**." + ] + }, + { + "cell_type": "markdown", + "id": "a84cfaa2", + "metadata": { + "solveit_ai": true + }, + "source": [ + "ok, so asyncio was only a fix for await syntax, not parallelism, it supports no parallelism\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Not quite — close, but there’s an important distinction.\n", + "\n", + "`asyncio` is **not parallelism** in the usual “two things executing at the exact same time on different CPU cores” sense.\n", + "\n", + "But it **is concurrency**: it lets many tasks be “in progress” at once by switching between them when they hit `await`.\n", + "\n", + "So:\n", + "\n", + "- **parallelism**: two things literally run at the same time\n", + "- **asyncio concurrency**: one thread takes turns between tasks at `await` points\n", + "\n", + "This is still very useful for I/O:\n", + "\n", + "```text\n", + "task A waits for network\n", + "task B runs\n", + "task C waits for disk/socket\n", + "task A resumes\n", + "```\n", + "\n", + "So I’d say:\n", + "\n", + "> `asyncio` was not just a syntax fix for `await`; it is a cooperative concurrency system. But by itself, it usually does not give CPU parallelism." + ] + }, + { + "cell_type": "markdown", + "id": "16c4c70b", + "metadata": { + "solveit_ai": true + }, + "source": [ + "ok, so if I run twice asyncio.run, I'm creating 2 event loops?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Yes — **if you call `asyncio.run(...)` twice sequentially**, you create **two separate event loops**, one after the other.\n", + "\n", + "Each call to:\n", + "\n", + "```python\n", + "asyncio.run(coro())\n", + "```\n", + "\n", + "roughly means:\n", + "\n", + "1. create a new event loop\n", + "2. run `coro()` until it finishes\n", + "3. close that event loop\n", + "\n", + "So:\n", + "\n", + "```python\n", + "asyncio.run(a())\n", + "asyncio.run(b())\n", + "```\n", + "\n", + "does **not** reuse the same loop. It creates one loop for `a`, closes it, then creates another loop for `b`.\n", + "\n", + "Important caveat: you generally **cannot call `asyncio.run(...)` from inside an already-running event loop**, which is why notebooks often use `await ...` instead." + ] + }, + { + "cell_type": "markdown", + "id": "d5bbafcc", + "metadata": { + "solveit_ai": true + }, + "source": [ + "so those would be 2 different threads?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "No — **two event loops does not mean two threads**.\n", + "\n", + "If you do:\n", + "\n", + "```python\n", + "asyncio.run(a())\n", + "asyncio.run(b())\n", + "```\n", + "\n", + "from the same normal Python thread, then both event loops are created and run on that **same thread**, sequentially:\n", + "\n", + "```text\n", + "main thread:\n", + " create loop 1 → run a → close loop 1\n", + " create loop 2 → run b → close loop 2\n", + "```\n", + "\n", + "An event loop is like a scheduler object. A thread is the OS execution lane that runs it. Different concepts." + ] + }, + { + "cell_type": "markdown", + "id": "8ab6f97a", + "metadata": { + "solveit_ai": true + }, + "source": [ + "can you make a chart of how main, asyncio thread, event loop and coroutine are related? sequence diagram unless you think something else is much more clear\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "A **flowchart** is clearer than a sequence diagram for this relationship, because we’re showing “contains / runs / schedules” rather than a time sequence.\n", + "\n", + "```python\n", + "mermaid('''\n", + "flowchart TD\n", + " P[Python process]\n", + "\n", + " P --> MT[Main thread]\n", + " P --> OT[Optional other thread]\n", + "\n", + " MT --> EL1[Event loop
scheduler object]\n", + " OT --> EL2[Another event loop
if you create one there]\n", + "\n", + " EL1 --> T1[Task]\n", + " EL1 --> T2[Task]\n", + " EL1 --> T3[Task]\n", + "\n", + " T1 --> C1[Coroutine
paused/resumable async function call]\n", + " T2 --> C2[Coroutine]\n", + " T3 --> C3[Coroutine]\n", + "\n", + " C1 --> A1[await point]\n", + " C2 --> A2[await point]\n", + " C3 --> A3[await point]\n", + "\n", + " A1 -. yields control .-> EL1\n", + " A2 -. yields control .-> EL1\n", + " A3 -. yields control .-> EL1\n", + "\n", + " MT -. runs .-> EL1\n", + " EL1 -. resumes one ready task at a time .-> T1\n", + " EL1 -. resumes one ready task at a time .-> T2\n", + " EL1 -. resumes one ready task at a time .-> T3\n", + "\n", + " style MT fill:#dff,stroke:#099\n", + " style EL1 fill:#ffd,stroke:#aa0\n", + " style T1 fill:#efe,stroke:#090\n", + " style T2 fill:#efe,stroke:#090\n", + " style T3 fill:#efe,stroke:#090\n", + " style C1 fill:#fef,stroke:#909\n", + " style C2 fill:#fef,stroke:#909\n", + " style C3 fill:#fef,stroke:#909\n", + "''')\n", + "```\n", + "\n", + "The key hierarchy is:\n", + "\n", + "```text\n", + "process\n", + " └── thread\n", + " └── event loop\n", + " └── tasks\n", + " └── coroutines\n", + "```\n", + "\n", + "And the key rule:\n", + "\n", + "```text\n", + "The thread runs the event loop.\n", + "The event loop schedules tasks.\n", + "Each task drives one coroutine.\n", + "A coroutine gives control back at await.\n", + "```\n", + "\n", + "So there is no special “asyncio thread” by default. Usually it is just:\n", + "\n", + "```text\n", + "main thread running an event loop\n", + "```\n", + "\n", + "unless you explicitly create another thread and run another event loop there." + ] + }, + { + "cell_type": "code", + "execution_count": null, + "id": "a7324e3f", + "metadata": {}, + "outputs": [ + { + "data": { + "text/html": [ + "
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\n", + "\n", + "```\n", + "\n", + "
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\n", + "flowchart TD\n", + " P[Python process]\n", + "\n", + " P --> MT[Main thread]\n", + " P --> OT[Optional other thread]\n", + "\n", + " MT --> EL1[Event loop<br/>scheduler object]\n", + " OT --> EL2[Another event loop<br/>if you create one there]\n", + "\n", + " EL1 --> T1[Task]\n", + " EL1 --> T2[Task]\n", + " EL1 --> T3[Task]\n", + "\n", + " T1 --> C1[Coroutine<br/>paused/resumable async function call]\n", + " T2 --> C2[Coroutine]\n", + " T3 --> C3[Coroutine]\n", + "\n", + " C1 --> A1[await point]\n", + " C2 --> A2[await point]\n", + " C3 --> A3[await point]\n", + "\n", + " A1 -. yields control .-> EL1\n", + " A2 -. yields control .-> EL1\n", + " A3 -. yields control .-> EL1\n", + "\n", + " MT -. runs .-> EL1\n", + " EL1 -. resumes one ready task at a time .-> T1\n", + " EL1 -. resumes one ready task at a time .-> T2\n", + " EL1 -. resumes one ready task at a time .-> T3\n", + "\n", + " style MT fill:#dff,stroke:#099\n", + " style EL1 fill:#ffd,stroke:#aa0\n", + " style T1 fill:#efe,stroke:#090\n", + " style T2 fill:#efe,stroke:#090\n", + " style T3 fill:#efe,stroke:#090\n", + " style C1 fill:#fef,stroke:#909\n", + " style C2 fill:#fef,stroke:#909\n", + " style C3 fill:#fef,stroke:#909\n", + "
" + ] + }, + "execution_count": null, + "metadata": {}, + "output_type": "execute_result" + } + ], + "source": [ + "mermaid('''\n", + "flowchart TD\n", + " P[Python process]\n", + "\n", + " P --> MT[Main thread]\n", + " P --> OT[Optional other thread]\n", + "\n", + " MT --> EL1[Event loop
scheduler object]\n", + " OT --> EL2[Another event loop
if you create one there]\n", + "\n", + " EL1 --> T1[Task]\n", + " EL1 --> T2[Task]\n", + " EL1 --> T3[Task]\n", + "\n", + " T1 --> C1[Coroutine
paused/resumable async function call]\n", + " T2 --> C2[Coroutine]\n", + " T3 --> C3[Coroutine]\n", + "\n", + " C1 --> A1[await point]\n", + " C2 --> A2[await point]\n", + " C3 --> A3[await point]\n", + "\n", + " A1 -. yields control .-> EL1\n", + " A2 -. yields control .-> EL1\n", + " A3 -. yields control .-> EL1\n", + "\n", + " MT -. runs .-> EL1\n", + " EL1 -. resumes one ready task at a time .-> T1\n", + " EL1 -. resumes one ready task at a time .-> T2\n", + " EL1 -. resumes one ready task at a time .-> T3\n", + "\n", + " style MT fill:#dff,stroke:#099\n", + " style EL1 fill:#ffd,stroke:#aa0\n", + " style T1 fill:#efe,stroke:#090\n", + " style T2 fill:#efe,stroke:#090\n", + " style T3 fill:#efe,stroke:#090\n", + " style C1 fill:#fef,stroke:#909\n", + " style C2 fill:#fef,stroke:#909\n", + " style C3 fill:#fef,stroke:#909\n", + "''')" + ] + }, + { + "cell_type": "markdown", + "id": "de6280eb", + "metadata": { + "solveit_ai": true + }, + "source": [ + "the optional other threads is what? you said it all runs in a single thread\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Good catch. Let me separate two cases.\n", + "\n", + "When people say **“asyncio is single-threaded”**, they usually mean:\n", + "\n", + "```text\n", + "one event loop runs in one thread\n", + "```\n", + "\n", + "So this part is the normal asyncio model:\n", + "\n", + "```text\n", + "Main thread\n", + " └── Event loop\n", + " └── many tasks/coroutines\n", + "```\n", + "\n", + "The **optional other thread** is not created by asyncio automatically. It only exists if **you explicitly create another thread**, like your sync `JupyUvi` path does:\n", + "\n", + "```python\n", + "@startthread\n", + "def run_server():\n", + " asyncio.run(server.serve())\n", + "```\n", + "\n", + "That creates:\n", + "\n", + "```text\n", + "Main notebook thread\n", + "Background server thread\n", + " └── its own event loop\n", + " └── uvicorn server coroutine\n", + "```\n", + "\n", + "So both statements are true, but for different scopes:\n", + "\n", + "- **one event loop** runs in **one thread**\n", + "- a Python process can have **multiple threads**\n", + "- each thread may have its **own event loop** if you create one there\n", + "- plain asyncio does not magically create extra threads for ordinary coroutines\n", + "\n", + "In your `JupyUvi` code, the sync version deliberately uses another thread so the notebook can keep running while uvicorn serves requests." + ] + }, + { + "cell_type": "markdown", + "id": "77f197cb", + "metadata": { + "solveit_ai": true + }, + "source": [ + "oh, let's see, our async start, creates a coroutine to be run in the main event loop (which is the notebook's). The \"sync\" version, actually creates a new thread and then inside that, it creates a new event loop, which presumable creates one more thread to run the coroutine?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Almost exactly — except the last part.\n", + "\n", + "For the **async start**:\n", + "\n", + "```text\n", + "main notebook thread\n", + " └── notebook event loop\n", + " └── uvicorn coroutine/task\n", + "```\n", + "\n", + "Yes.\n", + "\n", + "For the **“sync” start**:\n", + "\n", + "```text\n", + "main notebook thread\n", + "background thread\n", + " └── new event loop\n", + " └── uvicorn coroutine/task\n", + "```\n", + "\n", + "The new event loop **does not create one more thread**. It runs inside the background thread.\n", + "\n", + "So:\n", + "\n", + "```python\n", + "asyncio.run(server.serve())\n", + "```\n", + "\n", + "inside the background thread means:\n", + "\n", + "```text\n", + "in this same background thread:\n", + " create event loop\n", + " run coroutine on that loop\n", + " close event loop when done\n", + "```\n", + "\n", + "No extra thread is created by `asyncio.run()` itself." + ] + }, + { + "cell_type": "markdown", + "id": "7c13ffb3", + "metadata": { + "solveit_ai": true + }, + "source": [ + "I'm confused, then why when we run asyncio.run in the main thread, it does not run in the main thread but rather in another one?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "It **does** run in the main thread.\n", + "\n", + "This:\n", + "\n", + "```python\n", + "asyncio.run(coro())\n", + "```\n", + "\n", + "means:\n", + "\n", + "```text\n", + "same current thread:\n", + " create event loop\n", + " run coro on that event loop\n", + " close event loop\n", + "```\n", + "\n", + "So if you call it from the main thread, it runs in the main thread.\n", + "\n", + "The reason your “sync” `JupyUvi` case runs elsewhere is not because of `asyncio.run`. It’s because you wrapped it in a thread first:\n", + "\n", + "```python\n", + "@startthread\n", + "def run_server():\n", + " asyncio.run(server.serve())\n", + "```\n", + "\n", + "So the sequence is:\n", + "\n", + "```text\n", + "main thread calls startthread\n", + "startthread creates background thread\n", + "background thread calls asyncio.run(...)\n", + "background thread runs uvicorn event loop\n", + "```\n", + "\n", + "`asyncio.run` itself does not move anything to another thread." + ] + }, + { + "cell_type": "markdown", + "id": "c156d355", + "metadata": { + "solveit_ai": true + }, + "source": [ + "oh, makes sense. So that's why asyncio tasks blocking, will block the main thread. Meanwhile, blocking stuff on the startthread won't affect our main thread. \n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "Exactly.\n", + "\n", + "Small correction in wording:\n", + "\n", + "- an **asyncio task** doesn’t automatically block the main thread\n", + "- but if code running on the **main thread’s event loop** calls blocking sync code like `time.sleep(...)`, then yes, it blocks the main thread/event loop\n", + "\n", + "So:\n", + "\n", + "```text\n", + "async start:\n", + " uvicorn runs on notebook/main event loop\n", + " blocking stop() blocks that same loop\n", + " uvicorn cannot finish shutdown\n", + "```\n", + "\n", + "Whereas:\n", + "\n", + "```text\n", + "sync/startthread start:\n", + " uvicorn runs on background thread\n", + " main thread can block-wait in stop()\n", + " background thread still gets to finish shutdown\n", + "```\n", + "\n", + "That’s the core distinction." + ] + }, + { + "cell_type": "markdown", + "id": "c67c1738", + "metadata": { + "solveit_ai": true + }, + "source": [ + "so, what's the advantage of having async start here?\n", + "\n", + "##### 🤖Reply🤖\n", + "\n", + "The advantage of `start_async()` is mainly: **it lets you run uvicorn inside an already-async environment without creating another thread**.\n", + "\n", + "In this notebook context, that means:\n", + "\n", + "```text\n", + "notebook event loop\n", + " ├── your async code\n", + " └── uvicorn server task\n", + "```\n", + "\n", + "Potential benefits:\n", + "\n", + "- no extra background thread\n", + "- cleaner if the rest of your workflow is already async\n", + "- easier to coordinate with other async resources/tasks\n", + "- avoids some cross-thread issues\n", + "\n", + "But the cost is exactly what we found:\n", + "\n", + "- you must not use blocking waits like `time.sleep`\n", + "- shutdown needs `await server.stop_async()`\n", + "- any blocking code can freeze both notebook async work and the server\n", + "\n", + "So in this specific `JupyUvi` case, `start_async()` is useful if you want a fully-async API. If most notebook users are doing normal sync cells, the threaded `start()` path is probably simpler and more forgiving." + ] + }, + { + "cell_type": "code", + "execution_count": null, + "id": "827fe416", + "metadata": { + "hide_input": true + }, + "outputs": [ + { + "data": { + "text/html": [ + "
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\n", + "sequenceDiagram\n", + " participant NB as Notebook (main thread / event loop)\n", + " participant T as Background Thread (own loop)\n", + " participant UV as Uvicorn\n", + "\n", + " rect rgb(220, 240, 220)\n", + " Note over NB,UV: SYNC PATH — nb_serve + stop()\n", + " NB->>T: startthread(asyncio.run(server.serve()))\n", + " activate T\n", + " T->>UV: server.serve()\n", + " activate UV\n", + " loop time.sleep(0.01) on main thread — safe, T runs freely\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " loop time.sleep(0.1) on main thread — safe, T runs freely\n", + " NB->>NB: wait_port_free polls is_port_free\n", + " end\n", + " UV->>T: shutdown complete\n", + " deactivate UV\n", + " T-->>NB: port released\n", + " deactivate T\n", + " end\n", + "\n", + " rect rgb(255, 220, 220)\n", + " Note over NB,UV: ASYNC PATH — nb_serve_async + stop() ❌\n", + " NB->>NB: create_task(server.serve()) on notebook loop\n", + " activate UV\n", + " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " Note over NB: time.sleep(0.1) BLOCKS the event loop ❌\n", + " loop time.sleep(0.1) — loop is frozen, UV shutdown never runs\n", + " NB->>NB: wait_port_free polls is_port_free (always busy)\n", + " end\n", + " Note over NB,UV: TimeoutError after 20s — UV still running\n", + " end\n", + "\n", + " rect rgb(220, 230, 255)\n", + " Note over NB,UV: ASYNC PATH — nb_serve_async + stop_async() ✅\n", + " NB->>NB: create_task(server.serve()) on notebook loop\n", + " activate UV\n", + " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " loop await asyncio.sleep(0.1) — yields, UV shutdown runs ✅\n", + " NB->>NB: wait_port_free_async polls is_port_free\n", + " end\n", + " UV-->>NB: shutdown complete, port released\n", + " deactivate UV\n", + " end\n", + "
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\n" + ], + "text/markdown": [ + "
\n", + "\n", + "```html\n", + "
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\n", + "\n", + "```\n", + "\n", + "
" + ], + "text/plain": [ + "
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" + ] + }, + "execution_count": null, + "metadata": {}, + "output_type": "execute_result" + } + ], + "source": [ + "mermaid('''\n", + "sequenceDiagram\n", + " participant NB as Notebook (main thread / event loop)\n", + " participant T as Background Thread (own loop)\n", + " participant UV as Uvicorn\n", + "\n", + " rect rgb(220, 240, 220)\n", + " Note over NB,UV: SYNC PATH — nb_serve + stop()\n", + " NB->>T: startthread(asyncio.run(server.serve()))\n", + " activate T\n", + " T->>UV: server.serve()\n", + " activate UV\n", + " loop time.sleep(0.01) on main thread — safe, T runs freely\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " loop time.sleep(0.1) on main thread — safe, T runs freely\n", + " NB->>NB: wait_port_free polls is_port_free\n", + " end\n", + " UV->>T: shutdown complete\n", + " deactivate UV\n", + " T-->>NB: port released\n", + " deactivate T\n", + " end\n", + "\n", + " rect rgb(255, 220, 220)\n", + " Note over NB,UV: ASYNC PATH — nb_serve_async + stop() ❌\n", + " NB->>NB: create_task(server.serve()) on notebook loop\n", + " activate UV\n", + " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " Note over NB: time.sleep(0.1) BLOCKS the event loop ❌\n", + " loop time.sleep(0.1) — loop is frozen, UV shutdown never runs\n", + " NB->>NB: wait_port_free polls is_port_free (always busy)\n", + " end\n", + " Note over NB,UV: TimeoutError after 20s — UV still running\n", + " end\n", + "\n", + " rect rgb(220, 230, 255)\n", + " Note over NB,UV: ASYNC PATH — nb_serve_async + stop_async() ✅\n", + " NB->>NB: create_task(server.serve()) on notebook loop\n", + " activate UV\n", + " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", + " NB->>NB: wait server.started\n", + " end\n", + " UV-->>NB: server.started = True\n", + " NB->>UV: server.should_exit = True\n", + " loop await asyncio.sleep(0.1) — yields, UV shutdown runs ✅\n", + " NB->>NB: wait_port_free_async polls is_port_free\n", + " end\n", + " UV-->>NB: shutdown complete, port released\n", + " deactivate UV\n", + " end\n", + "''')" + ] + } + ], + "metadata": { "solveit": { "default_code": true, "mode": "learning", "use_fence": false, - "use_thinking": false, + "use_thinking": true, "use_tools": true, "ver": 2 } From 6c014352e2cd1ac038652e3ab937390e4511545f Mon Sep 17 00:00:00 2001 From: Pol Alvarez Date: Wed, 20 May 2026 10:46:49 +0200 Subject: [PATCH 2/2] fixed some renamings --- fasthtml/jupyter.py | 20 +- nbs/api/06_jupyter.ipynb | 2456 +------------------------------------- 2 files changed, 43 insertions(+), 2433 deletions(-) diff --git a/fasthtml/jupyter.py b/fasthtml/jupyter.py index 7ccda46f..74b39fb3 100644 --- a/fasthtml/jupyter.py +++ b/fasthtml/jupyter.py @@ -36,28 +36,28 @@ async def nb_serve_async(app, log_level="error", port=8000, host='0.0.0.0', **kw # %% ../nbs/api/06_jupyter.ipynb #508917bc def is_port_free(port, host='localhost'): - s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) - s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) + sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) + sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) try: - s.bind((host, port)) - s.listen(1) + sock.bind((host, port)) + sock.listen(1) return True - except OSError as e: return False - finally: s.close() + except OSError: return False + finally: sock.close() # %% ../nbs/api/06_jupyter.ipynb #1779cb76 def wait_port_free(port, host='localhost', max_wait=20): "Wait for `port` to be free on `host`" - start = time.time() + start_time = time.time() while not is_port_free(port, host): - if time.time() - start > max_wait: raise TimeoutError(f"Port {host}:{port} not free after {max_wait}s") + if time.time() - start_time > max_wait: raise TimeoutError(f"Port {host}:{port} not free after {max_wait}s") time.sleep(0.1) async def wait_port_free_async(port, host='localhost', max_wait=20): "Async wait for `port` to be free on `host`" - start = time.time() + start_time = time.time() while not is_port_free(port, host): - if time.time() - start > max_wait: raise TimeoutError(f"Port {host}:{port} not free after {max_wait}s") + if time.time() - start_time > max_wait: raise TimeoutError(f"Port {host}:{port} not free after {max_wait}s") await asyncio.sleep(0.1) diff --git a/nbs/api/06_jupyter.ipynb b/nbs/api/06_jupyter.ipynb index 62d26e07..1d1b24e7 100644 --- a/nbs/api/06_jupyter.ipynb +++ b/nbs/api/06_jupyter.ipynb @@ -100,14 +100,14 @@ "source": [ "#| export\n", "def is_port_free(port, host='localhost'):\n", - " s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)\n", - " s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)\n", + " sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)\n", + " sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)\n", " try:\n", - " s.bind((host, port))\n", - " s.listen(1)\n", + " sock.bind((host, port))\n", + " sock.listen(1)\n", " return True\n", - " except OSError as e: return False\n", - " finally: s.close()" + " except OSError: return False\n", + " finally: sock.close()" ] }, { @@ -120,16 +120,16 @@ "#| export\n", "def wait_port_free(port, host='localhost', max_wait=20):\n", " \"Wait for `port` to be free on `host`\"\n", - " start = time.time()\n", + " start_time = time.time()\n", " while not is_port_free(port, host):\n", - " if time.time() - start > max_wait: raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + " if time.time() - start_time > max_wait: raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", " time.sleep(0.1)\n", "\n", "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", " \"Async wait for `port` to be free on `host`\"\n", - " start = time.time()\n", + " start_time = time.time()\n", " while not is_port_free(port, host):\n", - " if time.time() - start > max_wait: raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", + " if time.time() - start_time > max_wait: raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", " await asyncio.sleep(0.1)\n" ] }, @@ -465,12 +465,12 @@ "text/html": [ "\n", "\n", - "" + "" ], "text/plain": [ "HTML(\n", "\n", - ")" + ")" ] }, "metadata": {}, @@ -509,22 +509,22 @@ { "data": { "text/html": [ - "
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" ] }, "execution_count": null, @@ -830,2401 +830,11 @@ "execution_count": null, "id": "d211e8e2", "metadata": {}, - "outputs": [ - { - "name": "stderr", - "output_type": "stream", - "text": [ - "/Users/pengren/ws/nbdev/nbdev/export.py:55: UserWarning: Notebook '/Users/pengren/ws/fasthtml/nbs/api/06_jupyter_dup2.ipynb' uses `#| export` without `#| default_exp` cell.\n", - "Note nbdev2 no longer supports nbdev1 syntax. Run `nbdev-migrate` to upgrade.\n", - "See https://nbdev.fast.ai/getting_started.html for more information.\n", - " warn(f\"Notebook '{nbname}' uses `#| export` without `#| default_exp` cell.\\n\"\n" - ] - } - ], + "outputs": [], "source": [ "#| hide\n", "import nbdev; nbdev.nbdev_export()" ] - }, - { - "cell_type": "markdown", - "id": "d6eafdc3", - "metadata": {}, - "source": [ - "# Discussion" - ] - }, - { - "cell_type": "markdown", - "id": "e023c62c", - "metadata": { - "solveit_ai": true - }, - "source": [ - "it seems that some server.stop have timeout in the notebook above, I have the feeling it's only for async ones, is that correct?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Not quite.\n", - "\n", - "From the notebook **the async cases are definitely a problem**, but the timeouts are **not only** on async ones.\n", - "\n", - "What the notebook shows:\n", - "\n", - "- **Sync start/stop worked once**\n", - " - `server = JupyUvi(app, port=port)`\n", - " - `server.stop()` succeeded\n", - "- **Async-start cases timed out**\n", - " - `await server.start_async()` with `JupyUvi(..., start=False)`\n", - " - `await server.start()` with `JupyUviAsync(...)`\n", - "- **A later normal `JupyUvi(...).stop()` also timed out**\n", - " - after the notebook/HTMX example\n", - "\n", - "So your feeling is **partly right, but not completely**.\n", - "\n", - "The clearest reason the **async** ones fail is this:\n", - "\n", - "- `nb_serve_async()` starts `server.serve()` on the notebook’s **current event loop**\n", - "- then `stop()` is a **sync** method that does:\n", - " - `self.server.should_exit = True`\n", - " - then busy-waits with `time.sleep(...)`\n", - "\n", - "That busy wait can block the same loop the server needs in order to actually shut down.\n", - "\n", - "So this pattern is suspicious:\n", - "\n", - "```python\n", - "self.server.should_exit = True\n", - "wait_port_free(...)\n", - "```\n", - "\n", - "inside a **synchronous** `stop()` for a server that was started with `await server.serve()` on the notebook loop.\n", - "\n", - "A good mental model is:\n", - "\n", - "- **threaded server** (`nb_serve`) → sync `stop()` can work\n", - "- **event-loop server** (`nb_serve_async`) → sync `stop()` is risky, because it blocks shutdown\n", - "\n", - "So I’d phrase the conclusion like this:\n", - "\n", - "> The async shutdown path looks like the main systematic bug, but the notebook also contains at least one timeout on a non-async `JupyUvi.stop()`, so it’s not accurate to say it’s only async.\n", - "\n", - "A likely next fix is to make the async-started server use an **async stop** too, with `await asyncio.sleep(...)` instead of `time.sleep(...)`." - ] - }, - { - "cell_type": "markdown", - "id": "64108bf8", - "metadata": { - "solveit_ai": true - }, - "source": [ - "ok, so I think we should have async wait and sync wait right? can you refactor that?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — I’d split it by **waiting style**, not by “kind of server”.\n", - "\n", - "The core idea is:\n", - "\n", - "- if shutdown is happening from normal threaded/sync code, use `time.sleep`\n", - "- if shutdown is happening on the notebook event loop, use `await asyncio.sleep`\n", - "\n", - "A clean refactor is:\n", - "\n", - "```python\n", - "def wait_port_free(port, host='localhost', max_wait=20):\n", - " \"Wait for `port` to be free on `host`\"\n", - " start = time.time()\n", - " while not is_port_free(port, host):\n", - " if time.time() - start > max_wait:\n", - " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", - " time.sleep(0.1)\n", - "\n", - "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", - " \"Async wait for `port` to be free on `host`\"\n", - " start = time.time()\n", - " while not is_port_free(port, host):\n", - " if time.time() - start > max_wait:\n", - " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", - " await asyncio.sleep(0.1)\n", - "```\n", - "\n", - "Then make the stop methods match the start path:\n", - "\n", - "```python\n", - "class JupyUvi:\n", - " \"Start and stop a Jupyter compatible uvicorn server with ASGI `app` on `port` with `log_level`\"\n", - " def __init__(self, app, log_level=\"error\", host='0.0.0.0', port=8000, start=True, daemon=False, **kwargs):\n", - " self.kwargs = kwargs\n", - " store_attr(but='start')\n", - " self.server = None\n", - " if start: self.start()\n", - " if not os.environ.get('IN_SOLVEIT'): htmx_config_port(port)\n", - "\n", - " def start(self):\n", - " self.server = nb_serve(self.app, log_level=self.log_level, host=self.host, port=self.port, daemon=self.daemon, **self.kwargs)\n", - "\n", - " async def start_async(self):\n", - " self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs)\n", - "\n", - " def stop(self):\n", - " self.server.should_exit = True\n", - " wait_port_free(self.port, self.host)\n", - "\n", - " async def stop_async(self):\n", - " self.server.should_exit = True\n", - " await wait_port_free_async(self.port, self.host)\n", - "```\n", - "\n", - "Then your notebook usage becomes:\n", - "\n", - "- sync/threaded server:\n", - " ```python\n", - " server = JupyUvi(app, port=port)\n", - " server.stop()\n", - " ```\n", - "\n", - "- async-started server:\n", - " ```python\n", - " server = JupyUvi(app, port=port, start=False)\n", - " await server.start_async()\n", - " await server.stop_async()\n", - " ```\n", - "\n", - "I’d also say this makes `JupyUviAsync` unnecessary unless you really want the alternate API. The main thing is: **don’t call a blocking wait from the same event loop that must perform the shutdown**." - ] - }, - { - "cell_type": "markdown", - "id": "bc8bd31c", - "metadata": { - "solveit_ai": true - }, - "source": [ - "is there a way to DRY them?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — mostly.\n", - "\n", - "The **polling logic** can be shared, but the **actual waiting** still has to differ:\n", - "\n", - "- sync path uses `time.sleep(...)`\n", - "- async path uses `await asyncio.sleep(...)`\n", - "\n", - "So the usual DRY shape is:\n", - "\n", - "1. share the **deadline / condition** logic\n", - "2. keep two tiny wrappers for the actual sleep style\n", - "\n", - "For example, conceptually:\n", - "\n", - "```python\n", - "def _port_closed(port, host): return is_port_free(port, host)\n", - "```\n", - "\n", - "then:\n", - "\n", - "```python\n", - "# sync: while not _port_closed(...): time.sleep(...)\n", - "# async: while not _port_closed(...): await asyncio.sleep(...)\n", - "```\n", - "\n", - "That’s probably the best kind of DRY here, because trying to force one function to be both sync and async usually makes the API worse, not better.\n", - "\n", - "A slightly more DRY version is to share the timeout check too:\n", - "\n", - "```python\n", - "def _check_timeout(start, host, port, max_wait):\n", - " if time.time() - start > max_wait:\n", - " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", - "```\n", - "\n", - "Then both waiters become very small:\n", - "- check condition\n", - "- call `_check_timeout(...)`\n", - "- sleep in the appropriate way\n", - "\n", - "So: **yes, DRY the condition and timeout logic; keep separate sync/async wait functions**. That’s the cleanest balance." - ] - }, - { - "cell_type": "markdown", - "id": "55ad622b", - "metadata": { - "solveit_ai": true - }, - "source": [ - "can you flesh out some DRY options so I see which one I like better?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — there are a few sensible levels of DRY here, and they feel quite different stylistically.\n", - "\n", - "**Option 1: Minimal DRY**\n", - "Keep two public wait functions, but share the timeout/error logic.\n", - "\n", - "```python\n", - "def _check_wait(start, host, port, max_wait):\n", - " if time.time() - start > max_wait:\n", - " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", - "```\n", - "\n", - "```python\n", - "def wait_port_free(port, host='localhost', max_wait=20):\n", - " start = time.time()\n", - " while not is_port_free(port, host):\n", - " _check_wait(start, host, port, max_wait)\n", - " time.sleep(0.1)\n", - "\n", - "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", - " start = time.time()\n", - " while not is_port_free(port, host):\n", - " _check_wait(start, host, port, max_wait)\n", - " await asyncio.sleep(0.1)\n", - "```\n", - "\n", - "Why this is nice:\n", - "- very obvious\n", - "- very low cleverness\n", - "- easiest to maintain\n", - "\n", - "Why it’s not very DRY:\n", - "- loop body is still duplicated\n", - "\n", - "\n", - "**Option 2: Share the polling loop shape**\n", - "Factor out the “while condition + timeout” logic into a helper, and only vary the sleeper.\n", - "\n", - "Sync version:\n", - "\n", - "```python\n", - "def _wait_for(pred, sleep, timeout_msg, max_wait=20):\n", - " start = time.time()\n", - " while not pred():\n", - " if time.time() - start > max_wait: raise TimeoutError(timeout_msg)\n", - " sleep(0.1)\n", - "```\n", - "\n", - "Async version still needs its own helper:\n", - "\n", - "```python\n", - "async def _wait_for_async(pred, sleep, timeout_msg, max_wait=20):\n", - " start = time.time()\n", - " while not pred():\n", - " if time.time() - start > max_wait: raise TimeoutError(timeout_msg)\n", - " await sleep(0.1)\n", - "```\n", - "\n", - "Then:\n", - "\n", - "```python\n", - "def wait_port_free(port, host='localhost', max_wait=20):\n", - " return _wait_for(lambda: is_port_free(port, host), time.sleep,\n", - " f\"Port {host}:{port} not free after {max_wait}s\", max_wait)\n", - "\n", - "async def wait_port_free_async(port, host='localhost', max_wait=20):\n", - " return await _wait_for_async(lambda: is_port_free(port, host), asyncio.sleep,\n", - " f\"Port {host}:{port} not free after {max_wait}s\", max_wait)\n", - "```\n", - "\n", - "Why this is nice:\n", - "- the public functions become tiny\n", - "- reusable for other wait conditions later\n", - "\n", - "Why it’s slightly awkward:\n", - "- you still need both `_wait_for` and `_wait_for_async`\n", - "- more abstraction than option 1\n", - "\n", - "\n", - "**Option 3: One internal async core**\n", - "Make the core waiter async, and have the sync wrapper call it in a thread or fresh loop.\n", - "\n", - "Something like:\n", - "\n", - "```python\n", - "async def _wait_port_free(port, host='localhost', max_wait=20):\n", - " start = time.time()\n", - " while not is_port_free(port, host):\n", - " if time.time() - start > max_wait:\n", - " raise TimeoutError(f\"Port {host}:{port} not free after {max_wait}s\")\n", - " await asyncio.sleep(0.1)\n", - "```\n", - "\n", - "Then:\n", - "- `wait_port_free_async(...)` just awaits it\n", - "- `wait_port_free(...)` has to run that coroutine somehow\n", - "\n", - "Why this is nice:\n", - "- maximum logic sharing\n", - "\n", - "Why I’d be cautious:\n", - "- sync wrapper gets annoying fast\n", - "- notebook/event-loop situations are exactly where “just run the coroutine” gets fiddly\n", - "- more clever than helpful here\n", - "\n", - "\n", - "**Option 4: DRY at the stop-method level instead**\n", - "Instead of focusing on the waiters, make shutdown itself split into:\n", - "- one shared “signal shutdown”\n", - "- one sync wait\n", - "- one async wait\n", - "\n", - "For example:\n", - "\n", - "```python\n", - "def _begin_shutdown(server):\n", - " server.should_exit = True\n", - "```\n", - "\n", - "Then:\n", - "- `stop()` does `_begin_shutdown(...)` + `wait_port_free(...)`\n", - "- `stop_async()` does `_begin_shutdown(...)` + `await wait_port_free_async(...)`\n", - "\n", - "Why this is nice:\n", - "- matches the real conceptual split\n", - "- avoids over-abstracting the waiters\n", - "- probably the cleanest OO design here\n", - "\n", - "Why it’s less “pure DRY”:\n", - "- you still have two wait functions\n", - "\n", - "\n", - "My taste here:\n", - "\n", - "- **Option 1** if you want boring and robust\n", - "- **Option 4** if you want the cleanest API design\n", - "- **Option 2** if you expect to add more “wait until X” helpers later\n", - "- **Option 3** only if you really want a single core and don’t mind async/sync plumbing complexity\n", - "\n", - "If I were editing this notebook, I’d probably choose **Option 4 + Option 1**:\n", - "- shared shutdown trigger\n", - "- separate sync/async waiters\n", - "- tiny shared timeout helper\n", - "\n", - "That gives good clarity without being repetitive in the annoying parts.\n", - "\n", - "If you want, I can next write the exact refactor in the style of the current notebook — either **minimal-change**, **cleanest API**, or **most DRY**." - ] - }, - { - "cell_type": "markdown", - "id": "a5125455", - "metadata": { - "solveit_ai": true - }, - "source": [ - "what about passing the sleep method as a param?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — that can work, but only **up to a point**.\n", - "\n", - "The catch is:\n", - "\n", - "- `time.sleep` is a **normal function**\n", - "- `asyncio.sleep` is an **async function** that must be `await`ed\n", - "\n", - "So if you do this:\n", - "\n", - "```python\n", - "sleep_fn(...)\n", - "```\n", - "\n", - "that works for `time.sleep`, but not for `asyncio.sleep`.\n", - "\n", - "And if you do this:\n", - "\n", - "```python\n", - "await sleep_fn(...)\n", - "```\n", - "\n", - "that works for `asyncio.sleep`, but not for `time.sleep`.\n", - "\n", - "So passing `sleep` as a parameter is a nice DRY trick, but it **doesn't by itself remove the sync/async split**.\n", - "\n", - "The clean version is usually one of these:\n", - "\n", - "1. **Two helpers**, each taking a sleep fn\n", - " - sync helper calls `sleep_fn(dt)`\n", - " - async helper does `await sleep_fn(dt)`\n", - "\n", - "2. **One async core**\n", - " - always expects an awaitable sleeper\n", - " - sync code has to wrap `time.sleep`, which is usually a bit ugly\n", - "\n", - "So I’d say:\n", - "\n", - "> Passing the sleep method as a param is a good partial-DRY idea, but you still usually want separate sync and async wait functions.\n", - "\n", - "The smallest clean shape is probably:\n", - "\n", - "- shared timeout/check logic\n", - "- `wait_for(..., sleep_fn=time.sleep)`\n", - "- `wait_for_async(..., sleep_fn=asyncio.sleep)`\n", - "\n", - "If you want, I can sketch that exact shape in about 10 lines so you can judge whether it feels elegant or overabstracted." - ] - }, - { - "cell_type": "markdown", - "id": "a6fd6223", - "metadata": { - "solveit_ai": true - }, - "source": [ - "have a look at dialog ../../server-stop-repro did we miss any of the improvements? I never got a tiemout there, anything missing?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "I’m going to inspect that other dialog first so I can compare it against the notebook here and see whether any of the shutdown-related changes are missing.\n", - "\n", - "\n", - "
\n", - "pyrun(code='doc(load_dialog)')→'async def load_dialog(\\n src_dname:str…'\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_25xymgPGT4252rmtR16YP2fw\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"doc(load_dialog)\"\n", - " }\n", - " },\n", - " \"result\": \"async def load_dialog(\\n src_dname:str, # Dialog to load code from (path relative to solveit data dir, no .ipynb)\\n dname:str='', # Target dialog; defaults to current dialog\\n):\\n\\\"\\\"\\\"Run all code messages from `src_dname` into the target dialog's kernel and return dialog contents.\\\"\\\"\\\"\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I checked the available `load_dialog` helper first. It takes a source dialog path, runs that dialog’s code into the current kernel, and returns the dialog contents. Next I’m going to load `../../server-stop-repro` and inspect what’s in it.\n", - "\n", - "\n", - "
\n", - "pyrun(code="dlg_=await load_dialog('../../server-sto…")→'----------------------------------------…'\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_OoxLPiPQbONLF8xXzVnxX8zs\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"dlg_=await load_dialog('../../server-stop-repro')\\n(type(dlg_).__name__, getattr(dlg_, 'keys', None), len(dlg_) if hasattr(dlg_, '__len__') else None)\"\n", - " }\n", - " },\n", - " \"result\": \"---------------------------------------------------------------------------\\nNameError Traceback (most recent call last)\\nCell In[49], line 1\\n----> 1 await call_tool(pyrun, {'code': \\\"dlg_=await load_dialog('../../server-stop-repro')\\\\n(type(dlg_).__name__, getattr(dlg_, 'keys', None), len(dlg_) if hasattr(dlg_, '__len__') else None)\\\"})\\n\\nFile ~/ws/ipykernel-helper/ipykernel_helper/core.py:366, in call_tool(func, kw)\\n 364 async def call_tool(func, kw):\\n 365 \\\"Call `func(**kw)` with `coerce_inputs`\\\"\\n--> 366 return await maybe_await(func(**coerce_inputs(func, kw)))\\n\\nFile ~/ws/fastcore/fastcore/xtras.py:1057, in maybe_await(o)\\n 1055 \\\"Await `o` if needed, and return it\\\"\\n 1056 from inspect import isawaitable\\n-> 1057 return await o if isawaitable(o) else o\\n\\nFile ~/ws/safepyrun/safepyrun/core.py:340, in RunPython.__call__(self, code)\\n 338 tb = e.__traceback__\\n 339 while tb.tb_next and not tb.tb_frame.f_code.co_filename.startswith(' 340 raise e.with_traceback(tb) from None\\n\\nFile :1\\n----> 1 (type(dlg_).__name__, getattr(dlg_, 'keys', None), len(dlg_) if hasattr(dlg_, '__len__') else None)\\n\\nNameError: name 'getattr' is not defined\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I’m going to load that dialog into the current kernel and inspect its messages to compare it against this notebook’s server-stop patterns.\n", - "\n", - "\n", - "
\n", - "pyrun(code="dlg_=await load_dialog('../../server-sto…")→'----------------------------------------…'\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_seDgQKU9asBfav9M2rLmU4HI\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"dlg_=await load_dialog('../../server-stop-repro')\\n(type(dlg_).__name__, len(dlg_))\"\n", - " }\n", - " },\n", - " \"result\": \"---------------------------------------------------------------------------\\nTypeError Traceback (most recent call last)\\nCell In[50], line 1\\n----> 1 await call_tool(pyrun, {'code': \\\"dlg_=await load_dialog('../../server-stop-repro')\\\\n(type(dlg_).__name__, len(dlg_))\\\"})\\n\\nFile ~/ws/ipykernel-helper/ipykernel_helper/core.py:366, in call_tool(func, kw)\\n 364 async def call_tool(func, kw):\\n 365 \\\"Call `func(**kw)` with `coerce_inputs`\\\"\\n--> 366 return await maybe_await(func(**coerce_inputs(func, kw)))\\n\\nFile ~/ws/fastcore/fastcore/xtras.py:1057, in maybe_await(o)\\n 1055 \\\"Await `o` if needed, and return it\\\"\\n 1056 from inspect import isawaitable\\n-> 1057 return await o if isawaitable(o) else o\\n\\nFile ~/ws/safepyrun/safepyrun/core.py:340, in RunPython.__call__(self, code)\\n 338 tb = e.__traceback__\\n 339 while tb.tb_next and not tb.tb_frame.f_code.co_filename.startswith(' 340 raise e.with_traceback(tb) from None\\n\\nFile :1\\n----> 1 (type(dlg_).__name__, len(dlg_))\\n\\nTypeError: object of type 'ToolResponse' has no len()\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I’m going to inspect what `load_dialog('../../server-stop-repro')` returned, so I can read the loaded dialog content rather than guessing from the wrapper object.\n", - "\n", - "\n", - "
\n", - "pyrun(code='type(dlg_).__name__, xdir(dlg_)')→'----------------------------------------…'\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_aGxSJcAxOJHEBXoTX5xmZH0s\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"type(dlg_).__name__, xdir(dlg_)\"\n", - " }\n", - " },\n", - " \"result\": \"---------------------------------------------------------------------------\\nNameError Traceback (most recent call last)\\nCell In[51], line 1\\n----> 1 await call_tool(pyrun, {'code': 'type(dlg_).__name__, xdir(dlg_)'})\\n\\nFile ~/ws/ipykernel-helper/ipykernel_helper/core.py:366, in call_tool(func, kw)\\n 364 async def call_tool(func, kw):\\n 365 \\\"Call `func(**kw)` with `coerce_inputs`\\\"\\n--> 366 return await maybe_await(func(**coerce_inputs(func, kw)))\\n\\nFile ~/ws/fastcore/fastcore/xtras.py:1057, in maybe_await(o)\\n 1055 \\\"Await `o` if needed, and return it\\\"\\n 1056 from inspect import isawaitable\\n-> 1057 return await o if isawaitable(o) else o\\n\\nFile ~/ws/safepyrun/safepyrun/core.py:340, in RunPython.__call__(self, code)\\n 338 tb = e.__traceback__\\n 339 while tb.tb_next and not tb.tb_frame.f_code.co_filename.startswith(' 340 raise e.with_traceback(tb) from None\\n\\nFile :1\\n----> 1 (type(dlg_).__name__, xdir(dlg_))\\n\\nNameError: name 'dlg_' is not defined\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I’m going to load that dialog carefully and inspect what `load_dialog` returned, since my first probe showed it returns a `ToolResponse` wrapper rather than the dialog contents directly.\n", - "\n", - "\n", - "
\n", - "pyrun(code="dlg_=await load_dialog('../../server-sto…")→"('ToolResponse',\\n ToolResponse(content={…"\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_z35P3XNTpRNI30BS4jsg1BPI\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"dlg_=await load_dialog('../../server-stop-repro')\\ntype(dlg_).__name__, dlg_\"\n", - " }\n", - " },\n", - " \"result\": \"('ToolResponse',\\n ToolResponse(content={'_full': '{\\\"error\\\":\\\"Invalid path: ../../server-stop-repro\\\"}'}))\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I’m going to check how dialog paths are resolved, then search for `server-stop-repro` so I can compare it properly.\n", - "\n", - "\n", - "
\n", - "pyrun(code='doc(list_dialogs)')→'async def list_dialogs(\\n subpath:str=…'\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_M51G0hR1R6DYfqgEgd2Zac8c\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"doc(list_dialogs)\"\n", - " }\n", - " },\n", - " \"result\": \"async def list_dialogs(\\n subpath:str='', # Path under data root (absolute with `/`, else relative to current dialog's folder)\\n depth:int=1, # Directory depth\\n):\\n\\\"\\\"\\\"List dialogs and folders under `subpath`. Folders have `/` suffix.\\\"\\\"\\\"\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I tried loading `../../server-stop-repro`, but the tool says that path is invalid, so I don’t have the dialog contents yet. I’m going to inspect nearby dialog paths first so I can find the correct one.\n", - "\n", - "\n", - "
\n", - "pyrun(code="await list_dialogs('..', depth=3)")→"{'items': ['api/', 'api/00_core', 'api/0…"\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_AMbGfid5KMcz7niT7QQW2rM6\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"await list_dialogs('..', depth=3)\"\n", - " }\n", - " },\n", - " \"result\": \"{'items': ['api/', 'api/00_core', 'api/01_components', 'api/02_xtend', 'api/03_js', 'api/04_pico', 'api/05_svg', 'api/06_jupyter', 'api/06_jupyter_dup1', 'api/08_oauth', 'api/09_cli', 'explains/', 'explains/Stripe', 'explains/background_tasks', 'explains/explaining_xt_components', 'explains/faq', 'explains/imgs/', 'explains/minidataapi', 'explains/oauth', 'explains/routes', 'explains/websockets', 'fonts/', 'index', 'ref/', 'ref/concise_guide', 'ref/defining_xt_component', 'ref/handlers', 'ref/live_reload', 'ref/response_types', 'tutorials/', 'tutorials/by_example', 'tutorials/e2e', 'tutorials/imgs/', 'tutorials/jupyter_and_fasthtml', 'tutorials/quickstart-web-dev/', 'tutorials/quickstart_for_web_devs', 'unpublished/', 'unpublished/posts/', 'unpublished/tutorial_for_web_devs', 'unpublished/web-dev-tut/']}\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I looked one level up and a bit deeper. I can see the current notebook tree under `api/`, but there is no `server-stop-repro` there, so the relative path you gave doesn't resolve from this dialog.\n", - "\n", - "\n", - "
\n", - "pyrun(code="await list_dialogs('../..', depth=4)")→"{'items': ['demo/', 'docs/', 'examples/'…"\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_4OKJFWIQaAcWTCPitpE7hacv\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"await list_dialogs('../..', depth=4)\"\n", - " }\n", - " },\n", - " \"result\": \"{'items': ['demo/', 'docs/', 'examples/', 'fasthtml/', 'fasthtml/__pycache__/', 'nbs/', 'nbs/api/', 'nbs/api/00_core', 'nbs/api/01_components', 'nbs/api/02_xtend', 'nbs/api/03_js', 'nbs/api/04_pico', 'nbs/api/05_svg', 'nbs/api/06_jupyter', 'nbs/api/06_jupyter_dup1', 'nbs/api/08_oauth', 'nbs/api/09_cli', 'nbs/explains/', 'nbs/explains/Stripe', 'nbs/explains/background_tasks', 'nbs/explains/explaining_xt_components', 'nbs/explains/faq', 'nbs/explains/imgs/', 'nbs/explains/minidataapi', 'nbs/explains/oauth', 'nbs/explains/routes', 'nbs/explains/websockets', 'nbs/fonts/', 'nbs/index', 'nbs/ref/', 'nbs/ref/concise_guide', 'nbs/ref/defining_xt_component', 'nbs/ref/handlers', 'nbs/ref/live_reload', 'nbs/ref/response_types', 'nbs/tutorials/', 'nbs/tutorials/by_example', 'nbs/tutorials/e2e', 'nbs/tutorials/imgs/', 'nbs/tutorials/jupyter_and_fasthtml', 'nbs/tutorials/quickstart-web-dev/', 'nbs/tutorials/quickstart_for_web_devs', 'nbs/unpublished/', 'nbs/unpublished/posts/', 'nbs/unpublished/tutorial_for_web_devs', 'nbs/unpublished/web-dev-tut/', 'python_fasthtml.egg-info/', 'server-stop-repro', 'tests/', 'tools/']}\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I found the dialog path issue: `../../server-stop-repro` was invalid for `load_dialog`, but listing `../..` shows `server-stop-repro` does exist there. So the dialog is present; I just need to load it via the correct relative path from the current dialog folder.\n", - "\n", - "\n", - "
\n", - "pyrun(code="dlg_=await load_dialog('../..//server-st…")→"('ToolResponse',\\n ToolResponse(content={…"\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_bVzwr8lphMTdyraICA0vSvNy\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"dlg_=await load_dialog('../..//server-stop-repro')\\ntype(dlg_).__name__, dlg_\"\n", - " }\n", - " },\n", - " \"result\": \"('ToolResponse',\\n ToolResponse(content={'_full': '{\\\"error\\\":\\\"Invalid path: ../..//server-stop-repro\\\"}'}))\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I tried loading the dialog using the relative path you gave, but `load_dialog` rejected it as an invalid path. I then listed nearby dialogs and confirmed that a dialog named `server-stop-repro` does exist under the broader `fasthtml` area, so the issue is just the path format. Now I’m going to try loading it using an absolute-style dialog path.\n", - "\n", - "\n", - "
\n", - "pyrun(code="dlg_=await load_dialog('/ws/fasthtml/ser…")→"('ToolResponse',\\n ToolResponse(content={…"\n", - "\n", - "```json\n", - "{\n", - " \"id\": \"call_Qmm5cBEWqZJ2DNyPp8pLrwje\",\n", - " \"call\": {\n", - " \"function\": \"pyrun\",\n", - " \"arguments\": {\n", - " \"code\": \"dlg_=await load_dialog('/ws/fasthtml/server-stop-repro')\\ntype(dlg_).__name__, dlg_\"\n", - " }\n", - " },\n", - " \"result\": \"\\u2026onse',\\n ToolResponse(content={'_full': 'from fasthtml.common import *\\\\nfrom fasthtml.jupyter import *\\\\nfrom fastcore.utils import *\\\\nimport socket, time# Reproducing and fixing `JupyUvi.stop()` port races\\\\n\\\\nThis notebook shows why restarting a FastHTML/Jupyter uvicorn server can intermittently fail, and gives a small, testable fix.\\\\n\\\\nThe main issues identified and fixed are:\\\\n\\\\n1. **Wrong host in port checks** \\u2014 `JupyUvi` binds to `0.0.0.0`, but the port-free check was not using the same host, causing false \\\"port is free\\\" results.\\\\n2. **No timeout/error on `stop()`** \\u2014 The original `stop()` didn\\\\'t wait for the port to actually be released, so a restart immediately after could race with the old server still shutting down.\\\\n2. **Too-permissive port check (`SO_REUSEADDR`)** \\u2014 The original check set `SO_REUSEADDR` and only called `bind`, which can report a port as free even when a server is still winding down.\\\\n4. **No `listen()` call in port probe** \\u2014 A proper server does both `bind` and `listen`; the original check skipped `listen`, making it less representative of whether uvicorn could actually start.## 1. Stop not passing host to `wait_port_free`\\\\n\\\\n`wait_port_free` accepts a port & host, but JupyUvi.stop does not pass host along. By default `JupyUvi` binds to interface `0.0.0.0`. \\\\n\\\\nBinding to `0.0.0.0` means *listen to all IPv4 interfaces*. Binding to `localhost` means listen only on the loopback interface. \\\\n\\\\nBecause of that asymmetry `bind(\\\"0.0.0.0\\\", port)` needs the port to be available across all IPv4 interfaces, whereas `bind(\\\"localhost\\\", port)` only tests `loopback`. wait_port_free??\\\\n```python\\\\ndef wait_port_free(port, host=\\\\'localhost\\\\', max_wait=3):\\\\n \\\"Wait for `port` to be free on `host`\\\"\\\\n start_time = time.time()\\\\n while not is_port_free(port):\\\\n if time.time() - start_time>max_wait: return print(f\\\"Timeout\\\")\\\\n time.sleep(0.1)\\\\n```\\\\n\\\\n**File:** `~/ws/fasthtml/fasthtml/jupyter.py`JupyUvi??\\\\n```python\\\\nclass JupyUvi:\\\\n \\\"Start and stop a Jupyter compatible uvicorn server with ASGI `app` on `port` with `log_level`\\\"\\\\n def __init__(self, app, log_level=\\\"error\\\", host=\\\\'0.0.0.0\\\\', port=8000, start=True, daemon=False, **kwargs):\\\\n self.kwargs = kwargs\\\\n store_attr(but=\\\\'start\\\\')\\\\n self.server = None\\\\n if start: self.start()\\\\n if not os.environ.get(\\\\'IN_SOLVEIT\\\\'): htmx_config_port(port)\\\\n\\\\n def start(self):\\\\n self.server = nb_serve(self.app, log_level=self.log_level, host=self.host, port=self.port,daemon=self.daemon, **self.kwargs)\\\\n\\\\n async def start_async(self):\\\\n self.server = await nb_serve_async(self.app, log_level=self.log_level, host=self.host, port=self.port, **self.kwargs)\\\\n\\\\n def stop(self):\\\\n self.server.should_exit = True\\\\n wait_port_free(self.port)\\\\n```\\\\n\\\\n**File:** `~/ws/fasthtml/fasthtml/jupyter.py`ip = socket.gethostbyname(socket.gethostname())\\\\ns = socket.socket(); s.bind((ip,0)); s.listen()\\\\nport = s.getsockname()[1]def ok(h):\\\\n try:\\\\n x = socket.socket(); x.bind((h,port)); x.listen(); x.close()\\\\n return True\\\\n except OSError: return False\\\\n\\\\nok(\\\"127.0.0.1\\\"), ok(\\\"0.0.0.0\\\")(False, False)In order to demonstrate we will bind a non-loopback IPv4 interface. We use the following trick to get the IP of the non-loopback (the port 80 is just used for getting the IP, not binding anything to it).t = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)\\\\nt.connect((\\\"8.8.8.8\\\", 8004))\\\\nip = t.getsockname()[0]\\\\nt.close()\\\\n\\\\nip192.168.1.131Now we bind that IP to a random port so re-running the notebook won\\\\'t get any \\\"address already in use errors\\\".s = socket.socket()\\\\ns.bind((ip, 0))\\\\ns.listen()\\\\nport = s.getsockname()[1]\\\\n\\\\nport61208def ok(h, port):\\\\n x = socket.socket()\\\\n try:\\\\n x.bind((h, port))\\\\n x.listen()\\\\n return True\\\\n except OSError:\\\\n return False\\\\n finally:\\\\n x.close()\\\\n\\\\nok(\\\"127.0.0.1\\\", port), ok(\\\"0.0.0.0\\\", port)(True, False)We can see that effectively checkin if 127.0.0.1 is free returns true, while the actual 0.0.0.0 inteface is not. This is a long way to say we need to pass the host to the `wait_port_free` from `server.stop()`.\\\\ns.close()JupyUvi.stop??\\\\n```python\\\\ndef stop(self):\\\\n self.server.should_exit = True\\\\n wait_port_free(self.port)\\\\n```\\\\n\\\\n**File:** `~/ws/fasthtml/fasthtml/jupyter.py`Is my understanding corre\\u2026\"\n", - "}\n", - "```\n", - "\n", - "
\n", - "\n", - "I looked through `server-stop-repro`.\n", - "\n", - "What it **does include**:\n", - "\n", - "- passing `self.host` into `wait_port_free(...)`\n", - "- making `wait_port_free(...)` **raise** instead of just printing\n", - "- using a **stricter** port probe: `bind + listen`, without `SO_REUSEADDR`\n", - "- increasing the wait budget\n", - "- patching `JupyUvi.stop(...)` to actually wait for shutdown\n", - "\n", - "What it **does not include**:\n", - "\n", - "- a separate **async shutdown path** like `stop_async()`\n", - "- an async waiter such as `wait_port_free_async(...)`\n", - "- any real exercise of the notebook’s **async-started** server cases\n", - "\n", - "So yes: I think the main missing improvement there is exactly the one we were just discussing — **split sync and async waiting/shutdown**.\n", - "\n", - "Why you probably **never got a timeout there**:\n", - "\n", - "- that repro is focused on the **host mismatch / false-free probe** bug\n", - "- once that is fixed, the sync restart path works much more reliably\n", - "- it doesn’t really reproduce the **async event-loop shutdown** problem from the notebook above\n", - "\n", - "There’s also one more thing I think is still missing, separate from timeout handling:\n", - "\n", - "- `nb_serve(...)` waits in\n", - " ```python\n", - " while not server.started: time.sleep(0.01)\n", - " ```\n", - " and if bind/startup fails, that can effectively **hang until interrupted**, rather than surfacing a clean startup error quickly\n", - "\n", - "So my short verdict is:\n", - "\n", - "1. **Yes, one improvement is still missing:** async stop/wait support. \n", - "2. **Probably another one too:** better handling of **startup failure** in `nb_serve` / `nb_serve_async`, so failed bind doesn’t just sit in the “wait until started” loop.\n", - "\n", - "If I rank them by importance:\n", - "\n", - "- **first missing:** `stop_async()` / async wait\n", - "- **second missing:** startup-failure detection during `start()` / `start_async()`" - ] - }, - { - "cell_type": "markdown", - "id": "77cdeaa3", - "metadata": { - "solveit_ai": true - }, - "source": [ - "but I have wait_port_free_async right? am I missing something?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — **in this notebook, you do already have `wait_port_free_async`**.\n", - "\n", - "So the missing piece is **not** the async waiter itself. The thing that still looks missing is the **API path that uses it cleanly and consistently**.\n", - "\n", - "In other words:\n", - "\n", - "- you have `wait_port_free_async(...)`\n", - "- you also made `JupyUviAsync.stop(...)` use it\n", - "- but in `server-stop-repro`, that async path was **not part of the fix being exercised**\n", - "- and the main `JupyUvi` API still has:\n", - " - `start()`\n", - " - `start_async()`\n", - " - `stop()`\n", - " - but **no matching `stop_async()`**\n", - "\n", - "So I’d separate the two questions:\n", - "\n", - "1. **Do you have an async waiter?** \n", - " Yes.\n", - "\n", - "2. **Is the API fully cleaned up around it?** \n", - " Not quite — unless you want `JupyUviAsync` to be the official async stop path.\n", - "\n", - "That’s why I was saying the likely missing improvement is less “write `wait_port_free_async`” and more:\n", - "\n", - "- either add `JupyUvi.stop_async()`\n", - "- or decide `JupyUviAsync` is the intended async API and keep that as the one true path\n", - "\n", - "My instinct is that `JupyUvi` with both `start_async()` and `stop_async()` is the tidier public API." - ] - }, - { - "cell_type": "markdown", - "id": "e885b259", - "metadata": { - "solveit_ai": true - }, - "source": [ - "no, you misunderstand, the problem is that the CURRENT notebook has timeout, but in the repro one I never hit them (although it was always sync). Is there any missing gotcha? or it's just a matter of waiting more??\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "I don’t think it’s **just** “wait more”.\n", - "\n", - "The big missing gotcha is that the repro notebook is **always sync/threaded**, but the current notebook mixes in **async-started servers** and then later keeps going. That changes the failure mode.\n", - "\n", - "What I think is happening:\n", - "\n", - "- In the repro notebook, `stop()` is only testing the **threaded/sync** path, so it never hits the “blocked event loop during shutdown” issue.\n", - "- In the current notebook, once you do `await server.start_async()`, a later **sync** wait can interfere with the same loop that needs to finish shutting the server down.\n", - "- After one of those async shutdowns times out, later cells are **not cleanly independent** anymore — a later timeout may just be fallout from an earlier stop that didn’t complete when expected.\n", - "\n", - "There’s also a second gotcha:\n", - "\n", - "- your “is the port free?” probe is checking **raw rebinding**\n", - "- but the notebook does real HTTP/browser-ish traffic\n", - "- so after shutdown you can get a short-lived socket state issue that makes the probe say “still busy” even though the server is basically done\n", - "\n", - "So my short answer is:\n", - "\n", - "- **No, I wouldn’t treat this as only a matter of increasing the timeout**\n", - "- **Yes, there is a real missing gotcha:** the repro doesn’t exercise the async shutdown path, and the current notebook’s later failures may be contaminated by earlier timed-out async stops\n", - "\n", - "If I had to rank likelihood:\n", - "\n", - "1. **Main cause:** async-started server + shutdown path mismatch \n", - "2. **Secondary cause:** stricter port probe than the real restart path needs \n", - "3. **Only third:** timeout length itself\n", - "\n", - "A very practical reading is: if the repro is sync-only, its success does **not** rule out a real bug in the current notebook." - ] - }, - { - "cell_type": "markdown", - "id": "48f9c5d0", - "metadata": { - "solveit_ai": true - }, - "source": [ - "is_port_free does not do raw rebinding, it tries to listen to the host w/ reuse.\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — good catch. My phrasing there was wrong.\n", - "\n", - "If `is_port_free` does `bind(..., reuse) + listen()`, then it is **not** just “raw rebinding”. The more accurate concern is:\n", - "\n", - "- it is a **probe with different socket options**\n", - "- so it may not match uvicorn’s real bind/shutdown behavior exactly\n", - "\n", - "So I’d narrow the possible gotchas to these:\n", - "\n", - "1. **Host mismatch** \n", - " `0.0.0.0` vs `localhost` / `127.0.0.1` can absolutely change the result.\n", - "\n", - "2. **Async shutdown mismatch** \n", - " If the server was started on the notebook event loop, a sync stop path can still be the real problem.\n", - "\n", - "3. **Probe semantics with `SO_REUSEADDR`** \n", - " Not “raw rebinding”, but still possibly **more permissive than the real server bind**.\n", - "\n", - "So no, I would **not** jump to “just wait more”. \n", - "But I also wouldn’t blame the probe in the same way I described before.\n", - "\n", - "The sharper version is:\n", - "\n", - "> if the repro is sync-only and the failing notebook includes async-started servers, then the repro may simply be missing the failure mode.\n", - "\n", - "If you want, I can do one more pass and separate:\n", - "- things the repro definitely rules out\n", - "- things it does **not** rule out." - ] - }, - { - "cell_type": "markdown", - "id": "b2426637", - "metadata": { - "solveit_ai": true - }, - "source": [ - "but there's no host mismatch right? we are sending it on the wait & is port free checks.\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — in the **current notebook**, if `stop()` is doing:\n", - "\n", - "```python\n", - "wait_port_free(self.port, self.host)\n", - "```\n", - "\n", - "and `wait_port_free()` is calling:\n", - "\n", - "```python\n", - "is_port_free(port, host)\n", - "```\n", - "\n", - "then **there is no host mismatch** in that path.\n", - "\n", - "So that possible bug is **off the table** here.\n", - "\n", - "That leaves the more likely causes as:\n", - "\n", - "- **async-started server, sync-stopped server**\n", - " - `await server.start_async()`\n", - " - then later `server.stop()`\n", - " - that’s the strongest remaining suspect\n", - "\n", - "- **fallout from an earlier failed stop**\n", - " - once one shutdown times out, later cells may be testing a dirty state rather than a fresh one\n", - "\n", - "- **possibly just too short a wait**\n", - " - but I would treat that as a **secondary** explanation, not the main one\n", - "\n", - "So the updated conclusion is:\n", - "\n", - "> for the current notebook, the timeout is probably **not** about host mismatch; it’s more likely about the **async shutdown path** being handled with the wrong kind of stop/wait.\n", - "\n", - "And specifically, these two cells are the suspicious ones:\n", - "\n", - "```python\n", - "await server.start_async()\n", - "server.stop()\n", - "```\n", - "\n", - "and later:\n", - "\n", - "```python\n", - "await server.stop()\n", - "```\n", - "\n", - "because `stop()` is still a sync method there." - ] - }, - { - "cell_type": "markdown", - "id": "95f8a399", - "metadata": { - "solveit_ai": true - }, - "source": [ - "can you make a sequence diagram with mermaid that shows:\n", - "- the jupyUvi start / stop sequence (sync)\n", - "- the jupyUvi start / stop sequence (async)\n", - "- where each thing runs (main thread, async? etc...)\n", - "- where the sleep happens\n", - "\n", - "if you find anything else relevant for me to understand this, add it. I'm generally pretty bad thinking about how sync python works specially when there's async (and in the current notebook env). The mermaid chart should be code like this:\n", - "```python\n", - "mermaid('''...''')\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "```python\n", - "mermaid('''\n", - "sequenceDiagram\n", - " participant NB as Notebook (main thread / event loop)\n", - " participant T as Background Thread (own loop)\n", - " participant UV as Uvicorn\n", - "\n", - " rect rgb(220, 240, 220)\n", - " Note over NB,UV: SYNC PATH — nb_serve + stop()\n", - " NB->>T: startthread(asyncio.run(server.serve()))\n", - " activate T\n", - " T->>UV: server.serve()\n", - " activate UV\n", - " loop time.sleep(0.01) on main thread — safe, T runs freely\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " loop time.sleep(0.1) on main thread — safe, T runs freely\n", - " NB->>NB: wait_port_free polls is_port_free\n", - " end\n", - " UV->>T: shutdown complete\n", - " deactivate UV\n", - " T-->>NB: port released\n", - " deactivate T\n", - " end\n", - "\n", - " rect rgb(255, 220, 220)\n", - " Note over NB,UV: ASYNC PATH — nb_serve_async + stop() ❌\n", - " NB->>NB: create_task(server.serve()) on notebook loop\n", - " activate UV\n", - " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " Note over NB: time.sleep(0.1) BLOCKS the event loop ❌\n", - " loop time.sleep(0.1) — loop is frozen, UV shutdown never runs\n", - " NB->>NB: wait_port_free polls is_port_free (always busy)\n", - " end\n", - " Note over NB,UV: TimeoutError after 20s — UV still running\n", - " end\n", - "\n", - " rect rgb(220, 230, 255)\n", - " Note over NB,UV: ASYNC PATH — nb_serve_async + stop_async() ✅\n", - " NB->>NB: create_task(server.serve()) on notebook loop\n", - " activate UV\n", - " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " loop await asyncio.sleep(0.1) — yields, UV shutdown runs ✅\n", - " NB->>NB: wait_port_free_async polls is_port_free\n", - " end\n", - " UV-->>NB: shutdown complete, port released\n", - " deactivate UV\n", - " end\n", - "''')\n", - "```\n", - "\n", - "The key insight is in the middle block: `time.sleep` is not \"pause and let other things run\" — in an async context it is \"freeze everything\". The event loop is a single-threaded cooperative scheduler, so if you block it with `time.sleep`, the uvicorn shutdown coroutine that needs that same loop simply never gets a turn." - ] - }, - { - "cell_type": "code", - "execution_count": null, - "id": "a85e5b49", - "metadata": {}, - "outputs": [ - { - "data": { - "text/html": [ - "
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" - ], - "text/plain": [ - "" - ] - }, - "execution_count": null, - "metadata": {}, - "output_type": "execute_result" - } - ], - "source": [ - "enable_mermaid()" - ] - }, - { - "cell_type": "markdown", - "id": "c414c87c", - "metadata": { - "solveit_ai": true - }, - "source": [ - "can you explain the main concepts in a glossary? like asyncio etc... I'm familiar with the original python and I want to know how this was bolted on top. Is everything async? what happens if we don't use asyncio? I am familiar with go and other languages if that helps explain it. \n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Here’s the glossary version, with the “how was this bolted onto Python?” angle.\n", - "\n", - "**Synchronous Python**\n", - "\n", - "Normal Python is synchronous by default.\n", - "\n", - "```python\n", - "x = f()\n", - "y = g()\n", - "```\n", - "\n", - "means:\n", - "\n", - "1. call `f`\n", - "2. wait until `f` fully finishes\n", - "3. call `g`\n", - "\n", - "There is no automatic concurrency. If `f()` blocks on sleep, network, file IO, etc., the current thread just waits.\n", - "\n", - "---\n", - "\n", - "**Thread**\n", - "\n", - "A thread is an OS-managed execution lane inside one Python process.\n", - "\n", - "In your sync `JupyUvi` path:\n", - "\n", - "```python\n", - "startthread(daemon=daemon)\n", - "def run_server(): asyncio.run(server.serve())\n", - "```\n", - "\n", - "you create a **background thread**. That thread runs uvicorn. The notebook/main thread can then keep doing other things.\n", - "\n", - "So even if the main thread does:\n", - "\n", - "```python\n", - "time.sleep(0.1)\n", - "```\n", - "\n", - "the server thread can still run.\n", - "\n", - "That is why sync `stop()` works for the sync/threaded server.\n", - "\n", - "---\n", - "\n", - "**GIL**\n", - "\n", - "The GIL, or Global Interpreter Lock, means only one Python thread executes Python bytecode at once in normal CPython.\n", - "\n", - "But threads are still useful for IO-bound work, because when a thread waits on sockets, sleeps, or system calls, another thread can run.\n", - "\n", - "For your case: the uvicorn thread and notebook thread can coexist well enough because most server work is IO/event-loop waiting.\n", - "\n", - "---\n", - "\n", - "**Async / asyncio**\n", - "\n", - "`asyncio` is Python’s standard async concurrency system.\n", - "\n", - "It is **not** automatic. Code only becomes async when it is written using:\n", - "\n", - "```python\n", - "async def ...\n", - "await ...\n", - "asyncio.create_task(...)\n", - "```\n", - "\n", - "Asyncio uses an **event loop**.\n", - "\n", - "Think of the event loop as a scheduler that repeatedly says:\n", - "\n", - "> Which coroutine is ready to make progress now?\n", - "\n", - "But it only works if coroutines voluntarily yield control, usually with `await`.\n", - "\n", - "---\n", - "\n", - "**Coroutine**\n", - "\n", - "An `async def` function does not run immediately when called.\n", - "\n", - "```python\n", - "async def f():\n", - " ...\n", - "\n", - "coro = f()\n", - "```\n", - "\n", - "`coro` is a coroutine object. It runs only when awaited or scheduled:\n", - "\n", - "```python\n", - "await f()\n", - "```\n", - "\n", - "or:\n", - "\n", - "```python\n", - "asyncio.create_task(f())\n", - "```\n", - "\n", - "---\n", - "\n", - "**Event loop**\n", - "\n", - "The event loop runs coroutines and callbacks.\n", - "\n", - "In a notebook environment, there is usually already an event loop running, because the kernel needs to support top-level `await`.\n", - "\n", - "So when you write:\n", - "\n", - "```python\n", - "await server.start_async()\n", - "```\n", - "\n", - "you are using the notebook’s existing event loop.\n", - "\n", - "Important: an event loop is usually single-threaded.\n", - "\n", - "That means if you block that thread with normal blocking code, async tasks on that loop cannot progress.\n", - "\n", - "---\n", - "\n", - "**`await`**\n", - "\n", - "`await` means:\n", - "\n", - "> Pause this coroutine until this awaited thing is ready, and give the event loop a chance to run other tasks.\n", - "\n", - "This is the key difference between:\n", - "\n", - "```python\n", - "time.sleep(1)\n", - "```\n", - "\n", - "and:\n", - "\n", - "```python\n", - "await asyncio.sleep(1)\n", - "```\n", - "\n", - "`time.sleep(1)` says:\n", - "\n", - "> Freeze this whole thread for 1 second.\n", - "\n", - "`await asyncio.sleep(1)` says:\n", - "\n", - "> Pause me for 1 second, but let other async tasks run meanwhile.\n", - "\n", - "In Go terms, `await asyncio.sleep(...)` is closer to a goroutine blocking in a scheduler-friendly way. `time.sleep(...)` inside the event loop is closer to blocking the OS thread that the scheduler itself needs.\n", - "\n", - "---\n", - "\n", - "**Task**\n", - "\n", - "A task is a scheduled coroutine.\n", - "\n", - "```python\n", - "asyncio.create_task(server.serve())\n", - "```\n", - "\n", - "means:\n", - "\n", - "> Put `server.serve()` on the event loop so it can run concurrently with other async code.\n", - "\n", - "But “concurrently” here means cooperative concurrency on the event loop, not a new OS thread.\n", - "\n", - "So this:\n", - "\n", - "```python\n", - "asyncio.create_task(server.serve())\n", - "time.sleep(20)\n", - "```\n", - "\n", - "is bad if both happen on the event loop thread, because the task was scheduled but never gets CPU time while `time.sleep` blocks.\n", - "\n", - "---\n", - "\n", - "**Blocking**\n", - "\n", - "Blocking means “this function does not return until some operation is done.”\n", - "\n", - "Examples:\n", - "\n", - "```python\n", - "time.sleep(1)\n", - "requests.get(...)\n", - "socket.accept()\n", - "```\n", - "\n", - "Blocking is normal in sync Python.\n", - "\n", - "Blocking is dangerous inside the event loop thread, because it prevents all async tasks on that loop from running.\n", - "\n", - "---\n", - "\n", - "**Non-blocking / async-friendly**\n", - "\n", - "Async-friendly code gives control back to the event loop while waiting:\n", - "\n", - "```python\n", - "await asyncio.sleep(1)\n", - "await client.get(...)\n", - "await queue.get()\n", - "```\n", - "\n", - "This lets other scheduled tasks continue.\n", - "\n", - "---\n", - "\n", - "**Is everything async?**\n", - "\n", - "No.\n", - "\n", - "Most Python code is still sync unless explicitly written as async.\n", - "\n", - "In your notebook you currently have both worlds:\n", - "\n", - "1. **sync/threaded server path**\n", - " ```python\n", - " nb_serve(...)\n", - " ```\n", - " starts uvicorn in another thread with its own event loop.\n", - "\n", - "2. **async notebook-loop server path**\n", - " ```python\n", - " await nb_serve_async(...)\n", - " ```\n", - " starts uvicorn as a task on the current notebook event loop.\n", - "\n", - "These are quite different architectures.\n", - "\n", - "---\n", - "\n", - "**What happens if we don’t use asyncio?**\n", - "\n", - "Then you’re in normal sync Python.\n", - "\n", - "For a server, you still need some way for the server to run while the notebook continues. Common options are:\n", - "\n", - "1. run the server in the foreground \n", - " - simple, but notebook is occupied\n", - "\n", - "2. run the server in a background thread \n", - " - what `nb_serve(...)` does\n", - "\n", - "3. run the server in a separate process \n", - " - stronger isolation, more overhead\n", - "\n", - "So if you don’t use asyncio directly, your sync `JupyUvi` path still works because it hides asyncio inside a background thread:\n", - "\n", - "```python\n", - "asyncio.run(server.serve())\n", - "```\n", - "\n", - "That creates and runs an event loop inside that background thread.\n", - "\n", - "---\n", - "\n", - "**`asyncio.run(...)`**\n", - "\n", - "This is the bridge from sync code into async code.\n", - "\n", - "```python\n", - "asyncio.run(coro())\n", - "```\n", - "\n", - "means:\n", - "\n", - "1. create a new event loop\n", - "2. run the coroutine until done\n", - "3. close the loop\n", - "\n", - "But you generally cannot call `asyncio.run(...)` from inside an already-running event loop. That is why notebooks often need special handling.\n", - "\n", - "In your sync server path, this is fine because it runs inside a new background thread.\n", - "\n", - "---\n", - "\n", - "**Notebook top-level `await`**\n", - "\n", - "Normal Python files cannot do this at top level:\n", - "\n", - "```python\n", - "await something()\n", - "```\n", - "\n", - "But notebooks can.\n", - "\n", - "That means the notebook kernel already manages an event loop for you.\n", - "\n", - "Convenient, but it also means this mistake is easy:\n", - "\n", - "```python\n", - "await server.start_async()\n", - "server.stop() # sync blocking wait\n", - "```\n", - "\n", - "because `server.stop()` blocks the same thread/event loop the server needs to shut down.\n", - "\n", - "---\n", - "\n", - "**Uvicorn / ASGI app**\n", - "\n", - "FastHTML is an ASGI web app.\n", - "\n", - "Uvicorn is an ASGI server. Internally it is async. Its main server loop is essentially async machinery handling sockets and HTTP.\n", - "\n", - "So even if you start it from sync code, uvicorn itself still runs async internally.\n", - "\n", - "The question is: **where is that async loop running?**\n", - "\n", - "- sync `nb_serve`: in a background thread\n", - "- async `nb_serve_async`: on the notebook’s event loop\n", - "\n", - "That location determines whether `time.sleep` is safe.\n", - "\n", - "---\n", - "\n", - "**Your concrete bug pattern**\n", - "\n", - "This is okay:\n", - "\n", - "```python\n", - "server = JupyUvi(app)\n", - "server.stop()\n", - "```\n", - "\n", - "because:\n", - "\n", - "- uvicorn runs in background thread\n", - "- main thread does blocking wait\n", - "- background thread still shuts down server\n", - "\n", - "This is risky/bad:\n", - "\n", - "```python\n", - "server = JupyUvi(app, start=False)\n", - "await server.start_async()\n", - "server.stop()\n", - "```\n", - "\n", - "because:\n", - "\n", - "- uvicorn runs on notebook event loop\n", - "- `server.stop()` uses blocking `time.sleep`\n", - "- event loop is blocked\n", - "- uvicorn cannot finish shutdown\n", - "- port never becomes free\n", - "- timeout\n", - "\n", - "This is the matching async version:\n", - "\n", - "```python\n", - "server = JupyUvi(app, start=False)\n", - "await server.start_async()\n", - "await server.stop_async()\n", - "```\n", - "\n", - "because:\n", - "\n", - "- uvicorn runs on notebook event loop\n", - "- `stop_async()` uses `await asyncio.sleep`\n", - "- event loop gets chances to run uvicorn shutdown\n", - "\n", - "---\n", - "\n", - "**Go comparison**\n", - "\n", - "In Go, goroutines are scheduled by the Go runtime, and blocking operations are generally integrated with the scheduler. You can often write blocking-looking code and still get efficient concurrency.\n", - "\n", - "In Python asyncio, concurrency is more explicit:\n", - "\n", - "- `async def` marks async functions\n", - "- `await` marks yield points\n", - "- blocking sync calls do not automatically become scheduler-friendly\n", - "\n", - "A Go-ish mental translation:\n", - "\n", - "| Go | Python asyncio |\n", - "|---|---|\n", - "| `go f()` | `asyncio.create_task(f())` |\n", - "| blocking channel receive | `await queue.get()` |\n", - "| `time.Sleep(...)` in goroutine | `await asyncio.sleep(...)` |\n", - "| blocking the scheduler thread | `time.sleep(...)` inside event loop |\n", - "| goroutine | coroutine/task, but more explicit/cooperative |\n", - "\n", - "Python also has real threads and processes, so asyncio is just one concurrency model, not the whole story.\n", - "\n", - "---\n", - "\n", - "**Rule of thumb for this notebook**\n", - "\n", - "Use paired APIs:\n", - "\n", - "```python\n", - "server.start()\n", - "server.stop()\n", - "```\n", - "\n", - "for sync/threaded mode.\n", - "\n", - "Use:\n", - "\n", - "```python\n", - "await server.start_async()\n", - "await server.stop_async()\n", - "```\n", - "\n", - "for notebook-event-loop async mode.\n", - "\n", - "Avoid mixing:\n", - "\n", - "```python\n", - "await server.start_async()\n", - "server.stop()\n", - "```\n", - "\n", - "That mixed mode is where your timeout makes conceptual sense." - ] - }, - { - "cell_type": "markdown", - "id": "37f05450", - "metadata": { - "solveit_ai": true - }, - "source": [ - "you are giving me too much info at once. First of all what IS a coroutine? is it just a concept? why is the event loop single-threaded?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "A **coroutine** in Python is a real runtime object, not just a concept.\n", - "\n", - "When you write:\n", - "\n", - "```python\n", - "async def f(): ...\n", - "```\n", - "\n", - "calling `f()` does **not** run the function body. It creates a coroutine object: a paused computation that knows “when someone awaits/schedules me, start running here.”\n", - "\n", - "Example:\n", - "\n", - "```python\n", - "c = f() # creates coroutine object\n", - "await c # actually runs it\n", - "```\n", - "\n", - "So a coroutine is like a function call that can be **paused and resumed**.\n", - "\n", - "The pause points are `await`s. At an `await`, the coroutine says to the event loop:\n", - "\n", - "> I’m waiting for something; you can run other coroutines meanwhile.\n", - "\n", - "About the event loop being single-threaded: that’s mostly a design choice for simplicity and predictability.\n", - "\n", - "A Python asyncio event loop usually runs in **one OS thread** and manages many coroutines by switching between them only at `await` points. This avoids many classic thread problems:\n", - "\n", - "- no two coroutines unexpectedly modify the same object at the exact same time\n", - "- switching happens at explicit `await` points\n", - "- less locking is needed\n", - "\n", - "So the model is:\n", - "\n", - "```text\n", - "one thread\n", - "one event loop\n", - "many paused/resumable coroutines\n", - "```\n", - "\n", - "It’s not that async *must* be single-threaded in all possible systems. It’s that Python’s `asyncio` model is mainly **cooperative multitasking inside one thread**." - ] - }, - { - "cell_type": "markdown", - "id": "a84cfaa2", - "metadata": { - "solveit_ai": true - }, - "source": [ - "ok, so asyncio was only a fix for await syntax, not parallelism, it supports no parallelism\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Not quite — close, but there’s an important distinction.\n", - "\n", - "`asyncio` is **not parallelism** in the usual “two things executing at the exact same time on different CPU cores” sense.\n", - "\n", - "But it **is concurrency**: it lets many tasks be “in progress” at once by switching between them when they hit `await`.\n", - "\n", - "So:\n", - "\n", - "- **parallelism**: two things literally run at the same time\n", - "- **asyncio concurrency**: one thread takes turns between tasks at `await` points\n", - "\n", - "This is still very useful for I/O:\n", - "\n", - "```text\n", - "task A waits for network\n", - "task B runs\n", - "task C waits for disk/socket\n", - "task A resumes\n", - "```\n", - "\n", - "So I’d say:\n", - "\n", - "> `asyncio` was not just a syntax fix for `await`; it is a cooperative concurrency system. But by itself, it usually does not give CPU parallelism." - ] - }, - { - "cell_type": "markdown", - "id": "16c4c70b", - "metadata": { - "solveit_ai": true - }, - "source": [ - "ok, so if I run twice asyncio.run, I'm creating 2 event loops?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Yes — **if you call `asyncio.run(...)` twice sequentially**, you create **two separate event loops**, one after the other.\n", - "\n", - "Each call to:\n", - "\n", - "```python\n", - "asyncio.run(coro())\n", - "```\n", - "\n", - "roughly means:\n", - "\n", - "1. create a new event loop\n", - "2. run `coro()` until it finishes\n", - "3. close that event loop\n", - "\n", - "So:\n", - "\n", - "```python\n", - "asyncio.run(a())\n", - "asyncio.run(b())\n", - "```\n", - "\n", - "does **not** reuse the same loop. It creates one loop for `a`, closes it, then creates another loop for `b`.\n", - "\n", - "Important caveat: you generally **cannot call `asyncio.run(...)` from inside an already-running event loop**, which is why notebooks often use `await ...` instead." - ] - }, - { - "cell_type": "markdown", - "id": "d5bbafcc", - "metadata": { - "solveit_ai": true - }, - "source": [ - "so those would be 2 different threads?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "No — **two event loops does not mean two threads**.\n", - "\n", - "If you do:\n", - "\n", - "```python\n", - "asyncio.run(a())\n", - "asyncio.run(b())\n", - "```\n", - "\n", - "from the same normal Python thread, then both event loops are created and run on that **same thread**, sequentially:\n", - "\n", - "```text\n", - "main thread:\n", - " create loop 1 → run a → close loop 1\n", - " create loop 2 → run b → close loop 2\n", - "```\n", - "\n", - "An event loop is like a scheduler object. A thread is the OS execution lane that runs it. Different concepts." - ] - }, - { - "cell_type": "markdown", - "id": "8ab6f97a", - "metadata": { - "solveit_ai": true - }, - "source": [ - "can you make a chart of how main, asyncio thread, event loop and coroutine are related? sequence diagram unless you think something else is much more clear\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "A **flowchart** is clearer than a sequence diagram for this relationship, because we’re showing “contains / runs / schedules” rather than a time sequence.\n", - "\n", - "```python\n", - "mermaid('''\n", - "flowchart TD\n", - " P[Python process]\n", - "\n", - " P --> MT[Main thread]\n", - " P --> OT[Optional other thread]\n", - "\n", - " MT --> EL1[Event loop
scheduler object]\n", - " OT --> EL2[Another event loop
if you create one there]\n", - "\n", - " EL1 --> T1[Task]\n", - " EL1 --> T2[Task]\n", - " EL1 --> T3[Task]\n", - "\n", - " T1 --> C1[Coroutine
paused/resumable async function call]\n", - " T2 --> C2[Coroutine]\n", - " T3 --> C3[Coroutine]\n", - "\n", - " C1 --> A1[await point]\n", - " C2 --> A2[await point]\n", - " C3 --> A3[await point]\n", - "\n", - " A1 -. yields control .-> EL1\n", - " A2 -. yields control .-> EL1\n", - " A3 -. yields control .-> EL1\n", - "\n", - " MT -. runs .-> EL1\n", - " EL1 -. resumes one ready task at a time .-> T1\n", - " EL1 -. resumes one ready task at a time .-> T2\n", - " EL1 -. resumes one ready task at a time .-> T3\n", - "\n", - " style MT fill:#dff,stroke:#099\n", - " style EL1 fill:#ffd,stroke:#aa0\n", - " style T1 fill:#efe,stroke:#090\n", - " style T2 fill:#efe,stroke:#090\n", - " style T3 fill:#efe,stroke:#090\n", - " style C1 fill:#fef,stroke:#909\n", - " style C2 fill:#fef,stroke:#909\n", - " style C3 fill:#fef,stroke:#909\n", - "''')\n", - "```\n", - "\n", - "The key hierarchy is:\n", - "\n", - "```text\n", - "process\n", - " └── thread\n", - " └── event loop\n", - " └── tasks\n", - " └── coroutines\n", - "```\n", - "\n", - "And the key rule:\n", - "\n", - "```text\n", - "The thread runs the event loop.\n", - "The event loop schedules tasks.\n", - "Each task drives one coroutine.\n", - "A coroutine gives control back at await.\n", - "```\n", - "\n", - "So there is no special “asyncio thread” by default. Usually it is just:\n", - "\n", - "```text\n", - "main thread running an event loop\n", - "```\n", - "\n", - "unless you explicitly create another thread and run another event loop there." - ] - }, - { - "cell_type": "code", - "execution_count": null, - "id": "a7324e3f", - "metadata": {}, - "outputs": [ - { - "data": { - "text/html": [ - "
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\n", - "\n", - "```html\n", - "
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\n", - "\n", - "```\n", - "\n", - "
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" - ] - }, - "execution_count": null, - "metadata": {}, - "output_type": "execute_result" - } - ], - "source": [ - "mermaid('''\n", - "flowchart TD\n", - " P[Python process]\n", - "\n", - " P --> MT[Main thread]\n", - " P --> OT[Optional other thread]\n", - "\n", - " MT --> EL1[Event loop
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Let me separate two cases.\n", - "\n", - "When people say **“asyncio is single-threaded”**, they usually mean:\n", - "\n", - "```text\n", - "one event loop runs in one thread\n", - "```\n", - "\n", - "So this part is the normal asyncio model:\n", - "\n", - "```text\n", - "Main thread\n", - " └── Event loop\n", - " └── many tasks/coroutines\n", - "```\n", - "\n", - "The **optional other thread** is not created by asyncio automatically. It only exists if **you explicitly create another thread**, like your sync `JupyUvi` path does:\n", - "\n", - "```python\n", - "@startthread\n", - "def run_server():\n", - " asyncio.run(server.serve())\n", - "```\n", - "\n", - "That creates:\n", - "\n", - "```text\n", - "Main notebook thread\n", - "Background server thread\n", - " └── its own event loop\n", - " └── uvicorn server coroutine\n", - "```\n", - "\n", - "So both statements are true, but for different scopes:\n", - "\n", - "- **one event loop** runs in **one thread**\n", - "- a Python process can have **multiple threads**\n", - "- each thread may have its **own event loop** if you create one there\n", - "- plain asyncio does not magically create extra threads for ordinary coroutines\n", - "\n", - "In your `JupyUvi` code, the sync version deliberately uses another thread so the notebook can keep running while uvicorn serves requests." - ] - }, - { - "cell_type": "markdown", - "id": "77f197cb", - "metadata": { - "solveit_ai": true - }, - "source": [ - "oh, let's see, our async start, creates a coroutine to be run in the main event loop (which is the notebook's). The \"sync\" version, actually creates a new thread and then inside that, it creates a new event loop, which presumable creates one more thread to run the coroutine?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Almost exactly — except the last part.\n", - "\n", - "For the **async start**:\n", - "\n", - "```text\n", - "main notebook thread\n", - " └── notebook event loop\n", - " └── uvicorn coroutine/task\n", - "```\n", - "\n", - "Yes.\n", - "\n", - "For the **“sync” start**:\n", - "\n", - "```text\n", - "main notebook thread\n", - "background thread\n", - " └── new event loop\n", - " └── uvicorn coroutine/task\n", - "```\n", - "\n", - "The new event loop **does not create one more thread**. It runs inside the background thread.\n", - "\n", - "So:\n", - "\n", - "```python\n", - "asyncio.run(server.serve())\n", - "```\n", - "\n", - "inside the background thread means:\n", - "\n", - "```text\n", - "in this same background thread:\n", - " create event loop\n", - " run coroutine on that loop\n", - " close event loop when done\n", - "```\n", - "\n", - "No extra thread is created by `asyncio.run()` itself." - ] - }, - { - "cell_type": "markdown", - "id": "7c13ffb3", - "metadata": { - "solveit_ai": true - }, - "source": [ - "I'm confused, then why when we run asyncio.run in the main thread, it does not run in the main thread but rather in another one?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "It **does** run in the main thread.\n", - "\n", - "This:\n", - "\n", - "```python\n", - "asyncio.run(coro())\n", - "```\n", - "\n", - "means:\n", - "\n", - "```text\n", - "same current thread:\n", - " create event loop\n", - " run coro on that event loop\n", - " close event loop\n", - "```\n", - "\n", - "So if you call it from the main thread, it runs in the main thread.\n", - "\n", - "The reason your “sync” `JupyUvi` case runs elsewhere is not because of `asyncio.run`. It’s because you wrapped it in a thread first:\n", - "\n", - "```python\n", - "@startthread\n", - "def run_server():\n", - " asyncio.run(server.serve())\n", - "```\n", - "\n", - "So the sequence is:\n", - "\n", - "```text\n", - "main thread calls startthread\n", - "startthread creates background thread\n", - "background thread calls asyncio.run(...)\n", - "background thread runs uvicorn event loop\n", - "```\n", - "\n", - "`asyncio.run` itself does not move anything to another thread." - ] - }, - { - "cell_type": "markdown", - "id": "c156d355", - "metadata": { - "solveit_ai": true - }, - "source": [ - "oh, makes sense. So that's why asyncio tasks blocking, will block the main thread. Meanwhile, blocking stuff on the startthread won't affect our main thread. \n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "Exactly.\n", - "\n", - "Small correction in wording:\n", - "\n", - "- an **asyncio task** doesn’t automatically block the main thread\n", - "- but if code running on the **main thread’s event loop** calls blocking sync code like `time.sleep(...)`, then yes, it blocks the main thread/event loop\n", - "\n", - "So:\n", - "\n", - "```text\n", - "async start:\n", - " uvicorn runs on notebook/main event loop\n", - " blocking stop() blocks that same loop\n", - " uvicorn cannot finish shutdown\n", - "```\n", - "\n", - "Whereas:\n", - "\n", - "```text\n", - "sync/startthread start:\n", - " uvicorn runs on background thread\n", - " main thread can block-wait in stop()\n", - " background thread still gets to finish shutdown\n", - "```\n", - "\n", - "That’s the core distinction." - ] - }, - { - "cell_type": "markdown", - "id": "c67c1738", - "metadata": { - "solveit_ai": true - }, - "source": [ - "so, what's the advantage of having async start here?\n", - "\n", - "##### 🤖Reply🤖\n", - "\n", - "The advantage of `start_async()` is mainly: **it lets you run uvicorn inside an already-async environment without creating another thread**.\n", - "\n", - "In this notebook context, that means:\n", - "\n", - "```text\n", - "notebook event loop\n", - " ├── your async code\n", - " └── uvicorn server task\n", - "```\n", - "\n", - "Potential benefits:\n", - "\n", - "- no extra background thread\n", - "- cleaner if the rest of your workflow is already async\n", - "- easier to coordinate with other async resources/tasks\n", - "- avoids some cross-thread issues\n", - "\n", - "But the cost is exactly what we found:\n", - "\n", - "- you must not use blocking waits like `time.sleep`\n", - "- shutdown needs `await server.stop_async()`\n", - "- any blocking code can freeze both notebook async work and the server\n", - "\n", - "So in this specific `JupyUvi` case, `start_async()` is useful if you want a fully-async API. If most notebook users are doing normal sync cells, the threaded `start()` path is probably simpler and more forgiving." - ] - }, - { - "cell_type": "code", - "execution_count": null, - "id": "827fe416", - "metadata": { - "hide_input": true - }, - "outputs": [ - { - "data": { - "text/html": [ - "
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\n", - "\n", - "```\n", - "\n", - "
" - ], - "text/plain": [ - "
\n", - "sequenceDiagram\n", - " participant NB as Notebook (main thread / event loop)\n", - " participant T as Background Thread (own loop)\n", - " participant UV as Uvicorn\n", - "\n", - " rect rgb(220, 240, 220)\n", - " Note over NB,UV: SYNC PATH — nb_serve + stop()\n", - " NB->>T: startthread(asyncio.run(server.serve()))\n", - " activate T\n", - " T->>UV: server.serve()\n", - " activate UV\n", - " loop time.sleep(0.01) on main thread — safe, T runs freely\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " loop time.sleep(0.1) on main thread — safe, T runs freely\n", - " NB->>NB: wait_port_free polls is_port_free\n", - " end\n", - " UV->>T: shutdown complete\n", - " deactivate UV\n", - " T-->>NB: port released\n", - " deactivate T\n", - " end\n", - "\n", - " rect rgb(255, 220, 220)\n", - " Note over NB,UV: ASYNC PATH — nb_serve_async + stop() ❌\n", - " NB->>NB: create_task(server.serve()) on notebook loop\n", - " activate UV\n", - " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " Note over NB: time.sleep(0.1) BLOCKS the event loop ❌\n", - " loop time.sleep(0.1) — loop is frozen, UV shutdown never runs\n", - " NB->>NB: wait_port_free polls is_port_free (always busy)\n", - " end\n", - " Note over NB,UV: TimeoutError after 20s — UV still running\n", - " end\n", - "\n", - " rect rgb(220, 230, 255)\n", - " Note over NB,UV: ASYNC PATH — nb_serve_async + stop_async() ✅\n", - " NB->>NB: create_task(server.serve()) on notebook loop\n", - " activate UV\n", - " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " loop await asyncio.sleep(0.1) — yields, UV shutdown runs ✅\n", - " NB->>NB: wait_port_free_async polls is_port_free\n", - " end\n", - " UV-->>NB: shutdown complete, port released\n", - " deactivate UV\n", - " end\n", - "
" - ] - }, - "execution_count": null, - "metadata": {}, - "output_type": "execute_result" - } - ], - "source": [ - "mermaid('''\n", - "sequenceDiagram\n", - " participant NB as Notebook (main thread / event loop)\n", - " participant T as Background Thread (own loop)\n", - " participant UV as Uvicorn\n", - "\n", - " rect rgb(220, 240, 220)\n", - " Note over NB,UV: SYNC PATH — nb_serve + stop()\n", - " NB->>T: startthread(asyncio.run(server.serve()))\n", - " activate T\n", - " T->>UV: server.serve()\n", - " activate UV\n", - " loop time.sleep(0.01) on main thread — safe, T runs freely\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " loop time.sleep(0.1) on main thread — safe, T runs freely\n", - " NB->>NB: wait_port_free polls is_port_free\n", - " end\n", - " UV->>T: shutdown complete\n", - " deactivate UV\n", - " T-->>NB: port released\n", - " deactivate T\n", - " end\n", - "\n", - " rect rgb(255, 220, 220)\n", - " Note over NB,UV: ASYNC PATH — nb_serve_async + stop() ❌\n", - " NB->>NB: create_task(server.serve()) on notebook loop\n", - " activate UV\n", - " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " Note over NB: time.sleep(0.1) BLOCKS the event loop ❌\n", - " loop time.sleep(0.1) — loop is frozen, UV shutdown never runs\n", - " NB->>NB: wait_port_free polls is_port_free (always busy)\n", - " end\n", - " Note over NB,UV: TimeoutError after 20s — UV still running\n", - " end\n", - "\n", - " rect rgb(220, 230, 255)\n", - " Note over NB,UV: ASYNC PATH — nb_serve_async + stop_async() ✅\n", - " NB->>NB: create_task(server.serve()) on notebook loop\n", - " activate UV\n", - " loop await asyncio.sleep(0.01) — yields, loop runs UV startup\n", - " NB->>NB: wait server.started\n", - " end\n", - " UV-->>NB: server.started = True\n", - " NB->>UV: server.should_exit = True\n", - " loop await asyncio.sleep(0.1) — yields, UV shutdown runs ✅\n", - " NB->>NB: wait_port_free_async polls is_port_free\n", - " end\n", - " UV-->>NB: shutdown complete, port released\n", - " deactivate UV\n", - " end\n", - "''')" - ] } ], "metadata": {