A LocalProtocolError("not in a reusable state") exception is regularly raised from the start_next_cycle() call in hypercorn.asyncio.H11Server.recycle_or_close().

Could this be a state problem in hypercorn? A similar issue affected some example code of the h11 project (https://github.com/python-hyper/h11/issues/70). I'm seeing a lot of these exceptions (10 in a 22 hour period) but I'm not sure what the impact is on my code as I've not finished investigating the side-effect. At the moment I don't think I've lost any data but what's causing the state exception?

asyncio ERROR # Exception in callback H11Server.recycle_or_close(<Task finishe...> result=None>)
handle: <Handle H11Server.recycle_or_close(<Task finishe...> result=None>)>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/asyncio/events.py", line 88, in _run
    self._context.run(self._callback, *self._args)
  File "/usr/local/lib/python3.7/site-packages/hypercorn/asyncio/h11.py", line 103, in recycle_or_close
    self.connection.start_next_cycle()
  File "/usr/local/lib/python3.7/site-packages/h11/_connection.py", line 204, in start_next_cycle
    self._cstate.start_next_cycle()
  File "/usr/local/lib/python3.7/site-packages/h11/_state.py", line 298, in start_next_cycle
    raise LocalProtocolError("not in a reusable state")
h11._util.LocalProtocolError: not in a reusable state

I'm using hypercorn 0.6.0 and it's pulled in h11 0.8.1

What do you think about having another decorator like this that would allow you to control when server is shut down

This is useful when you need a server up for to X seconds, rather than forever. I think you could spin up a thread with a timer and have that call loop.stop() when done, but it's dirty.

@app.while_serving
async def shutdown_when_idle_for_seconds():
    while True:
        if condition:
            raise Shutdown
        await sleep(1)

Great for testing!

hi,

trying on Python-3.7 and 3.8rc the "hello" example, I fall on "add_signal_handler" not implemented in asyncio. is it Normal ?

I had hopes hypercorn was ok under windows, so I may have done something wrong ?

  File "C:\WinP\bd38\bucod\WPy64-3800rc1\python-3.8.0rc1.amd64\lib\site-packages\hypercorn\asyncio\run.py", line 212, in _run
    loop.add_signal_handler(signal.SIGINT, _signal_handler)
  File "C:\WinP\bd38\bucod\WPy64-3800rc1\python-3.8.0rc1.amd64\lib\asyncio\events.py", line 536, in add_signal_handler
    raise NotImplementedError
NotImplementedError

hello.py

async def app(scope, receive, send):
    if scope["type"] != "http":
        raise Exception("Only the HTTP protocol is supported")

    await send({
        'type': 'http.response.start',
        'status': 200,
        'headers': [
            (b'content-type', b'text/plain'),
            (b'content-length', b'5'),
        ],
    })
    await send({
        'type': 'http.response.body',
        'body': b'hello',
    })

Hi

I just found your excelent tuturial on how to use Quart with gunicorn, which I know isn't supported on Windows 10 so decided to attempt to use hypercorn instead. Unfortunately it's crashing giving this error.

hypercorn --keyfile key.pem --certfile cert.pem --ciphers ECDHE+AESGCM --bind localhost:5000 http2test:app Running on https://localhost:5000 (CTRL + C to quit) Traceback (most recent call last): File "c:\users\x\appdata\local\programs\python\python37-32\Lib\runpy.py", line 193, in run_module_as_main "main", mod_spec) File "c:\users\x\appdata\local\programs\python\python37-32\Lib\runpy.py", line 85, in run_code exec(code, run_globals) File "C:\Users\x.virtualenvs\QuartTest-s-3dKnLB\Scripts\hypercorn.exe_main.py", line 9, in File "c:\users\x.virtualenvs\quarttest-s-3dknlb\lib\site-packages\hypercorn_main.py", line 159, in main run_multiple(config) File "c:\users\x.virtualenvs\quarttest-s-3dknlb\lib\site-packages\hypercorn\run.py", line 234, in run_multiple process.start() File "c:\users\x\appdata\local\programs\python\python37-32\Lib\multiprocessing\process.py", line 112, in start self._popen = self._Popen(self) File "c:\users\x\appdata\local\programs\python\python37-32\Lib\multiprocessing\context.py", line 223, in _Popen return _default_context.get_context().Process._Popen(process_obj) File "c:\users\x\appdata\local\programs\python\python37-32\Lib\multiprocessing\context.py", line 322, in _Popen return Popen(process_obj) File "c:\users\x\appdata\local\programs\python\python37-32\Lib\multiprocessing\popen_spawn_win32.py", line 65, in init reduction.dump(process_obj, to_child) File "c:\users\x\appdata\local\programs\python\python37-32\Lib\multiprocessing\reduction.py", line 60, in dump ForkingPickler(file, protocol).dump(obj) TypeError: can't pickle SSLContext objects

Traceback (most recent call last): File "", line 1, in File "c:\users\x\appdata\local\programs\python\python37-32\Lib\multiprocessing\spawn.py", line 99, in spawn_main new_handle = reduction.steal_handle(parent_pid, pipe_handle) File "c:\users\x\appdata\local\programs\python\python37-32\Lib\multiprocessing\reduction.py", line 87, in steal_handle _winapi.DUPLICATE_SAME_ACCESS | _winapi.DUPLICATE_CLOSE_SOURCE) PermissionError: [WinError 5] Access is denied

Is there a working usage example? It's working fine with http1.

Thanks and keep up the great work!

I'm running a pretty simple quart app with hypercorn on a RHEL7 linux server. quart = 0.10.0 hypercorn = 0.9.0

I keep seeing these messages printed to standard out randomly every couple requests.

Task was destroyed but it is pending!
task: <Task pending coro=<ProtocolWrapper.send_task() done, defined at /root/.local/share/virtualenvs/atomix-Zh2dG3yU/lib/python3.7/site-packages/hypercorn/protocol/__init__.py:58> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f08fc3db1d0>()]>>
Task was destroyed but it is pending!
task: <Task pending coro=<ProtocolWrapper.send_task() done, defined at /root/.local/share/virtualenvs/atomix-Zh2dG3yU/lib/python3.7/site-packages/hypercorn/protocol/__init__.py:58> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f08f55188d0>()]>>

I'm pretty sure it has to do with hypercorn because I don't see the messages when I run the app using app.run(...). I'm having trouble narrowing down the problem anymore than that... Is anyone else seeing these messages?

Every once in a while I have a json request fail. The response body is mysteriously empty. The content-length is set to the correct non 0 value but nothing is in the body. I'm not sure if its related to this or not.

Hi all,

I am not sure whether this is really hypercorn issue, but could not imagine what else can be so please bear with me.

I am running a server with hypercorn on Ubuntu 20.04.

The problem is that it is runs with a duplicated process in background.

root     2278497  0.8  0.1  41872 33568 pts/7    S    10:03   0:00 /usr/bin/python3 /usr/local/bin/hypercorn -c config.toml main:app --reload
root     2278499  0.0  0.0  17304 11332 pts/7    S    10:03   0:00 /usr/bin/python3 -c from multiprocessing.resource_tracker import main;main(4)
root     2278500  0.7  0.1  41648 34148 pts/7    S    10:03   0:00 /usr/bin/python3 -c from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=5, pipe_handle=7) --multiprocessing-fork

The main process is 2278497, but there are duplicated processes 2278499 and 2278450. This causes unwanted effects by executing twice the same tasks.

How can I avoid that?

EDIT A minimal example:

# test_main.py
from fastapi import FastAPI

app = FastAPI()

@app.get("/")
async def root():
    return {"message": "Hello World"}

print("main module loaded.")

I then type:

sudo hypercorn test_main:app

and the stdout is:

main module loaded.
main module loaded.
[2022-11-02 15:08:45 +0100] [2364437] [INFO] Running on http://127.0.0.1:8000 (CTRL + C to quit)

If I use uvicorn the message is printed only one time, as expected:

$ sudo uvicorn test_main:app

main module loaded.
INFO:     Started server process [2364692]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

Hi @pgjones, I am currently using hypercorn with a Discord server that I created with quart. I have an a code excerpt that looks like this:

@app.route("/create_invite", methods=['GET'])
async def create_invite():
    """
    create an invite for the guild.
    """
    # wait_until_ready and check for valid connection is missing here
    guilds = client.guilds
    guild = guilds[0]
    link_str = 'n/a'
    for channel in guild.channels:
        if channel.name == 'general':
            print('creating invite')
            link = await channel.create_invite()
            link_str = str(link)
            break
    return jsonify({'invite_link': link_str}), 200

However, I think after 5 requests (link = await channel.create_invite()), I get throttled. When I run python main.py normally, I have to wait a bit of extra time; but when I run with hypercorn, I have to wait indefinitely. How can I fix this?

Describe the bug Hypercorn doesn't seem to be able to start with multiple workers on Windows. Seems like the socket is not ready to bind and Windows, therefore, throws an exception. This may be different on Unix systems.

Code snippet Starlette Hello World

main.py

from starlette.applications import Starlette
from starlette.responses import JSONResponse

app = Starlette(debug=True)


@app.route('/')
async def homepage(request):
    return JSONResponse({'hello': 'world'})

Expected behavior Hypercorn starts and is ready to serve with multiple workers.

Environment

• Windows 10
• Hypercorn: 0.5.3
• Python 3.6.6 (same issue with Python 3.7.2)
• pipenv
• Starlette 0.11.4

Additional context

Command: pipenv run hypercorn main:app -w 2

Exception:

Running on 127.0.0.1:8000 over http (CTRL + C to quit)
Process Process-2:

Traceback (most recent call last):
  File "Python36_64\Lib\multiprocessing\process.py", line 258, in _bootstrap
    self.run()
	
  File "Python36_64\Lib\multiprocessing\process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
	
  File ".virtualenvs\starlettehelloworld-wohnvuzv\lib\site-packages\hypercorn\asyncio\run.py", line 214, in asyncio_worker
    debug=config.debug,
	
  File ".virtualenvs\starlettehelloworld-wohnvuzv\lib\site-packages\hypercorn\asyncio\run.py", line 244, in _run
    loop.run_until_complete(main)
	
  File "Python36_64\Lib\asyncio\base_events.py", line 468, in run_until_complete
    return future.result()
	
  File ".virtualenvs\starlettehelloworld-wohnvuzv\lib\site-packages\hypercorn\asyncio\run.py", line 178, in worker_serve
    for sock in sockets
	
  File ".virtualenvs\starlettehelloworld-wohnvuzv\lib\site-packages\hypercorn\asyncio\run.py", line 178, in <listcomp>
    for sock in sockets
	
  File "Python36_64\Lib\asyncio\base_events.py", line 1065, in create_server
    sock.listen(backlog)
	
OSError: [WinError 10022] An invalid argument was supplied

I've been trying to get Hypercorn + Quart autoreloading on code change working and think I've found a bug.

The Hypercorn usage doc suggests the correct flag is "--reload" https://github.com/pgjones/hypercorn/blob/master/docs/usage.rst

When I use this it starts fine but the moment I edit the Quart source code file and save it Hypercorn crashes with this error: "unknown option --reload"

I've checked the Quart docs (https://pgjones.gitlab.io/quart/source/quart.app.html ) and it suggests the internal flag may be "use_reloader", however if I try that with Hypercorn it doesn't start, giving this error. "hypercorn: error: unrecognized arguments: --use_reloader"

In case it was a mismatch between versions I just tried uninstalling and re-installing both Quart and Hypercorn but there was no change. What's the best way to go about this?

Traceback (most recent call last):
File "/layers/[google.python.pip/pip/bin/hypercorn](http://google.python.pip/pip/bin/hypercorn)", line 8, in <module>
sys.exit(main())
File "/layers/[google.python.pip/pip/lib/python3.9/site-packages/hypercorn/](http://google.python.pip/pip/lib/python3.9/site-packages/hypercorn/)main.py", line 287, in main
run(config)
File "/layers/[google.python.pip/pip/lib/python3.9/site-packages/hypercorn/run.py](http://google.python.pip/pip/lib/python3.9/site-packages/hypercorn/run.py)", line 53, in run
processes = start_processes(config, worker_func, sockets, shutdown_event, ctx)
File "/layers/[google.python.pip/pip/lib/python3.9/site-packages/hypercorn/run.py](http://google.python.pip/pip/lib/python3.9/site-packages/hypercorn/run.py)", line 95, in start_processes
process.start()
File "/opt/python3.9/lib/python3.9/multiprocessing/process.py", line 121, in start
self._popen = self._Popen(self)
File "/opt/python3.9/lib/python3.9/multiprocessing/context.py", line 284, in _Popen
return Popen(process_obj)
File "/opt/python3.9/lib/python3.9/multiprocessing/popen_spawn_posix.py", line 32, in init
super().init(process_obj)
File "/opt/python3.9/lib/python3.9/multiprocessing/popen_fork.py", line 19, in init
self._launch(process_obj)
File "/opt/python3.9/lib/python3.9/multiprocessing/popen_spawn_posix.py", line 47, in _launch
reduction.dump(process_obj, fp)
File "/opt/python3.9/lib/python3.9/multiprocessing/reduction.py", line 60, in dump
ForkingPickler(file, protocol).dump(obj)
_pickle.PicklingError: Can't pickle <function getAvailableMemory at 0x3e3cacbe7550>: import of module 'module.name' failed

Hi I believe there is bug at

https://github.com/pgjones/hypercorn/blob/master/hypercorn/config.py#L158

when I use quart with signed certificate in quart as follows

app.run(ca_certs='ca.crt', certfile='cert.crt', kefile='key.pem')

I get the following

hypercorn/config.py", line 158, in create_ssl_context context.load_cert_chain(certfile=self.certfile, keyfile=self.keyfile) ssl.SSLError: [SSL] PEM lib (_ssl.c:3824)

I believe line https://github.com/pgjones/hypercorn/blob/master/hypercorn/config.py#L160 should be called before

https://github.com/pgjones/hypercorn/blob/master/hypercorn/config.py#L158

anyways I have reverted to unsigned certs for now and will probably just use gunicorn but I thought I would let you know about this bug and thank you for your quart project which I am really loving

How can I customize my error logs? In my access logs I have a header called x-trace-id, if it gives an error, I want to see that trace-id in the logs but I couldn't do it.

accesslog = 'app/storage/logs/access.log' errorlog = 'app/storage/logs/error.log' access_log_format = '~ %({x-forwarded-for}i)s ~ %({x-request-id}o)s ~ "%(r)s" %(s)s' umask = 0o771

access.log

[2022-11-25 00:59:03 +0300] [19978] [INFO] ~ 127.0.0.1 ~ 8f5c3abcbcbf47dabb5423ee3fde00e2 ~ "POST /api/v1/login 1.0" 500

error.log

[2022-11-25 00:59:03 +0300] [18440] [ERROR] Error in ASGI Framework

Hello, I'm using FastAPI subapps and Hypercorn access log shows only part of a request path (relative to a subapp root_path). Here is an example of request object passed to AccessLogAtoms constructor, the access log looks like

127.0.0.1:57296 - "GET /donation/93271720-ed81-4c4a-9b66-82a57088ea1f 1.1" 0.943398 200 207784 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:107.0) Gecko/20100101 Firefox/107.0"

Corresponding request object:

{'app': <fastapi.applications.FastAPI object at 0x7f163110b8b0>,
 'app_root_path': '',
 'asgi': {'spec_version': '2.1', 'version': '3.0'},
 'client': ('127.0.0.1', 37846),
 'endpoint': <function donation_image at 0x7f16313df400>,
 'extensions': {},
 'fastapi_astack': <contextlib.AsyncExitStack object at 0x7f162f5edd20>,
 'headers': [(b'host', b'localhost:8000'),
             (b'connection', b'keep-alive'),
             (b'upgrade-insecure-requests', b'1'),
             (b'user-agent',
              b'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, l'
              b'ike Gecko) HeadlessChrome/108.0.5359.29 Safari/537.36'),
             (b'accept',
              b'text/html,application/xhtml+xml,application/xml;q=0.9,image/'
              b'avif,image/webp,image/apng,*/*;q=0.8,application/signed-exch'
              b'ange;v=b3;q=0.9'),
             (b'sec-fetch-site', b'none'),
             (b'sec-fetch-mode', b'navigate'),
             (b'sec-fetch-user', b'?1'),
             (b'sec-fetch-dest', b'document'),
             (b'accept-encoding', b'gzip, deflate, br')],
 'http_version': '1.1',
 'method': 'GET',
 'path': '/donation/93271720-ed81-4c4a-9b66-82a57088ea1f',
 'path_params': {'donation_id': '93271720-ed81-4c4a-9b66-82a57088ea1f'},
 'query_string': b'',
 'raw_path': b'/preview/donation/93271720-ed81-4c4a-9b66-82a57088ea1f',
 'root_path': '/preview',
 'route': <fastapi.routing.APIRoute object at 0x7f1630fe1f90>,
 'router': <fastapi.routing.APIRouter object at 0x7f163110b910>,
 'scheme': 'http',
 'server': ('127.0.0.1', 8000),
 'type': 'http'}

With a such behavior it's difficult to differ similar subpaths from different subapps in access log.

After upgrading from ver. 0.11.2 to 0.14.3, my application container does not start on DO Apps with the following error:

Traceback (most recent call last):
  File "/usr/local/bin/hypercorn", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/site-packages/hypercorn/__main__.py", line 287, in main
    run(config)
  File "/usr/local/lib/python3.8/site-packages/hypercorn/run.py", line 52, in run
    shutdown_event = ctx.Event()
  File "/usr/local/lib/python3.8/multiprocessing/context.py", line 93, in Event
    return Event(ctx=self.get_context())
  File "/usr/local/lib/python3.8/multiprocessing/synchronize.py", line 324, in __init__
    self._cond = ctx.Condition(ctx.Lock())
  File "/usr/local/lib/python3.8/multiprocessing/context.py", line 68, in Lock
    return Lock(ctx=self.get_context())
  File "/usr/local/lib/python3.8/multiprocessing/synchronize.py", line 162, in __init__
    SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx)
  File "/usr/local/lib/python3.8/multiprocessing/synchronize.py", line 57, in __init__
    sl = self._semlock = _multiprocessing.SemLock(
OSError: [Errno 38] Function not implemented

Maybe we can't spawn on these kind of environments? I find a similar issue in AWS Lambda: https://stackoverflow.com/questions/34005930/multiprocessing-semlock-is-not-implemented-when-running-on-aws-lambda

Any information would be welcome.

Hi,

I'm faced up a weird behaviour when sending a large amount of data to hypercorn and flask. Here the steps to reproduce:

Generate the data file

dd if=/dev/urandom of=test.output bs=50M count=2

Start hypercorn

hypercorn app:app

Query

With curl:

curl -i -H 'Content-Length: 104857600' -X POST --data-binary "@test.output" http://localhost:8000/data

or a python code:

import requests requests.post("http://localhost:8000/data", files={"file": open('test.output', 'rb')})

With curl the output is :

HTTP/1.1 100 
date: Fri, 04 Nov 2022 14:03:58 GMT
server: hypercorn-h11

HTTP/1.1 400 
date: Fri, 04 Nov 2022 14:03:58 GMT
server: hypercorn-h11
Transfer-Encoding: chunked

With python client:

ConnectionError: ('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))

The flask code is the following:

import logging
from time import strftime
from flask import Flask, request

app = Flask(__name__)
logger = logging.getLogger('bench')
logger.setLevel(logging.ERROR)


@app.route('/data', methods=["POST"])
def send_data():
    """Send large data."""
    data = request.get_data()
    return str(len(data)) + "\n"


@app.before_request
def before_request_func():
    timestamp = strftime('[%Y-%m-%d %T %z]')
    logger.error(f"{timestamp} Request received")


@app.after_request
def after_request(response):
    timestamp = strftime('[%Y-%m-%d %T %z]')
    logger.error('%s - - %s "%s %s" %s', request.remote_addr, timestamp,
                 request.method, request.full_path, response.status)
    return response

Note: the code works with hypercorn + flask with a smallest payload but not with 100MB. Note: the output of the flask logger is empty. Which means that the request doesn't even reach flask (just hypercorn reject it somehow).

I have tried several combinations of configuration variables: h11_max_incomplete_size, h2_max_concurrent_streams, h2_max_header_list_size, h2_max_inbound_frame_size, max_app_queue_size, backlog, websocket_max_message_size without any success.

This code works with flask alone or gunicorn+flask.

Any thoughts? Thank your for your help :+1:

This patch fixes handling of StreamReader.read for the case when remote client terminates the connection. As documented here: https://docs.python.org/3.4/library/asyncio-stream.html#asyncio.StreamReader.read read method retuns b"" in this case.

    config = hypercorn.config.Config()
    config.bind = ["0.0.0.0:8088"]                 # OK
    config.bind = ["[::]:8088"]                    # OK
    config.bind = ["0.0.0.0:8088", "[::]:8088"]    # OSError: [Errno 98] Address already in use
    asyncio.run(hypercorn.asyncio.serve(endpoints.app, config))

The earlier listens on IPv4 only.

The variant in the middle actually listens on both IPv4 and IPv6 on my linux machine.

https://pgjones.gitlab.io/hypercorn/how_to_guides/binds.html seems to suggest the latter, but hypercorn fails with this hairy traceback:

[2022-10-11 10:03:29 +0900] [39335] [INFO] Running on http://0.0.0.0:8088 (CTRL + C to quit)
unhandled exception during asyncio.run() shutdown
task: <Task finished name='Task-2' coro=<Lifespan.handle_lifespan() done, defined at venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/lifespan.py:31> exception=LifespanFailureError('Lifespan failure in shutdown. \'Traceback (most recent call last):\n  File "/usr/lib/python3.10/asyncio/runners.py", line 44, in run\n    return loop.run_until_complete(main)\n  File "/usr/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete\n    return future.result()\n  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/__init__.py", line 49, in serve\n    await worker_serve(\n  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/run.py", line 120, in worker_serve\n    await asyncio.start_server(_server_callback, backlog=config.backlog, sock=sock)\n  File "/usr/lib/python3.10/asyncio/streams.py", line 84, in start_server\n    return await loop.create_server(factory, host, port, **kwds)\n  File "/usr/lib/python3.10/asyncio/base_events.py", line 1526, in create_server\n    server._start_serving()\n  File "/usr/lib/python3.10/asyncio/base_events.py", line 318, in _start_serving\n    sock.listen(self._backlog)\nOSError: [Errno 98] Address already in use\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n  File "venv-py3.10/lib/python3.10/site-packages/starlette/routing.py", line 648, in lifespan\n    await receive()\n  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/lifespan.py", line 92, in asgi_receive\n    return await self.app_queue.get()\n  File "/usr/lib/python3.10/asyncio/queues.py", line 159, in get\n    await getter\nasyncio.exceptions.CancelledError\n\'')>
Traceback (most recent call last):
  File "/usr/lib/python3.10/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete
    return future.result()
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/__init__.py", line 49, in serve
    await worker_serve(
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/run.py", line 120, in worker_serve
    await asyncio.start_server(_server_callback, backlog=config.backlog, sock=sock)
  File "/usr/lib/python3.10/asyncio/streams.py", line 84, in start_server
    return await loop.create_server(factory, host, port, **kwds)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 1526, in create_server
    server._start_serving()
  File "/usr/lib/python3.10/asyncio/base_events.py", line 318, in _start_serving
    sock.listen(self._backlog)
OSError: [Errno 98] Address already in use

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "venv-py3.10/lib/python3.10/site-packages/starlette/routing.py", line 648, in lifespan
    await receive()
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/lifespan.py", line 92, in asgi_receive
    return await self.app_queue.get()
  File "/usr/lib/python3.10/asyncio/queues.py", line 159, in get
    await getter
asyncio.exceptions.CancelledError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/lifespan.py", line 43, in handle_lifespan
    await self.app(
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/app_wrappers.py", line 33, in __call__
    await self.app(scope, receive, send)
  File "venv-py3.10/lib/python3.10/site-packages/fastapi/applications.py", line 270, in __call__
    await super().__call__(scope, receive, send)
  File "venv-py3.10/lib/python3.10/site-packages/starlette/applications.py", line 124, in __call__
    await self.middleware_stack(scope, receive, send)
  File "venv-py3.10/lib/python3.10/site-packages/starlette/middleware/errors.py", line 149, in __call__
    await self.app(scope, receive, send)
  File "venv-py3.10/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 51, in __call__
    await self.app(scope, receive, send)
  File "venv-py3.10/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 21, in __call__
    raise e
  File "venv-py3.10/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "venv-py3.10/lib/python3.10/site-packages/starlette/routing.py", line 669, in __call__
    await self.lifespan(scope, receive, send)
  File "venv-py3.10/lib/python3.10/site-packages/starlette/routing.py", line 652, in lifespan
    await send({"type": "lifespan.shutdown.failed", "message": exc_text})
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/lifespan.py", line 104, in asgi_send
    raise LifespanFailureError("shutdown", message["message"])
hypercorn.utils.LifespanFailureError: Lifespan failure in shutdown. 'Traceback (most recent call last):
  File "/usr/lib/python3.10/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete
    return future.result()
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/__init__.py", line 49, in serve
    await worker_serve(
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/run.py", line 120, in worker_serve
    await asyncio.start_server(_server_callback, backlog=config.backlog, sock=sock)
  File "/usr/lib/python3.10/asyncio/streams.py", line 84, in start_server
    return await loop.create_server(factory, host, port, **kwds)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 1526, in create_server
    server._start_serving()
  File "/usr/lib/python3.10/asyncio/base_events.py", line 318, in _start_serving
    sock.listen(self._backlog)
OSError: [Errno 98] Address already in use

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "venv-py3.10/lib/python3.10/site-packages/starlette/routing.py", line 648, in lifespan
    await receive()
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/lifespan.py", line 92, in asgi_receive
    return await self.app_queue.get()
  File "/usr/lib/python3.10/asyncio/queues.py", line 159, in get
    await getter
asyncio.exceptions.CancelledError
'
Traceback (most recent call last):
  File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "venvuth/__main__.py", line 59, in <module>
    asyncio.run(hypercorn.asyncio.serve(endpoints.app, config))
  File "/usr/lib/python3.10/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete
    return future.result()
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/__init__.py", line 49, in serve
    await worker_serve(
  File "venv-py3.10/lib/python3.10/site-packages/hypercorn/asyncio/run.py", line 120, in worker_serve
    await asyncio.start_server(_server_callback, backlog=config.backlog, sock=sock)
  File "/usr/lib/python3.10/asyncio/streams.py", line 84, in start_server
    return await loop.create_server(factory, host, port, **kwds)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 1526, in create_server
    server._start_serving()
  File "/usr/lib/python3.10/asyncio/base_events.py", line 318, in _start_serving
    sock.listen(self._backlog)
OSError: [Errno 98] Address already in use

So, well, I understand why this is happening, but the experience is a bit overwhelming... I feel that issues like this is why I keep seeing binds to 0.0.0.0 from junior developers.