version 3.3.0 hang problem

When I upgrade from version 3.2.10 to 3.3.0(daphne:2.5.0, python:3.8.2, django:2.2.16), the server looks like hang there randomly, no error info found in access.log and asgi.log.

the supervisord.conf as follow:

[fcgi-program:om]
directory=./
socket=tcp://0.0.0.0:8000
command=daphne -u ./daphne%(process_num)d.sock --fd 0 --access-log ./logs/access.log --proxy-headers MyProject.asgi:application
numprocs=4
process_name=asgi%(process_num)d
stdout_logfile=./logs/asgi.log
redirect_stderr=true

Now, I downgrade to 3.2.10, everything is OK.

Maybe modification about thread has some bugs or something I should do to adapt it.

[belongwqz]

Ah, you’re using Channels, you didn’t mention that initially - you might want to go look at issues over there, as it’s significantly more complex and a lot easier to deadlock yourself/write async code wrong.

If you’re running into this error, I will caution you that it is probably an early warning of an existing deadlock or race condition that was already in your code, so the best thing to do would be to track it down (via PYTHONASYNCIODEBUG, bisecting code, etc.) before it crops up on real user data.

There’s no core workaround for this reason - again, if you can somehow make it happen in a small sample, I can help work out why, but the fact you can’t implies it’s probably a bug in how the app is written at large.

The one way we have of modifying how SyncToAsync does its threading is the thread_sensitive_context attribute on the class, which you can overwrite with your own way of detecting contexts if you wish (it needs to be something with a get() method, and look vaguely like a ContextVar), so if you want to pursue that road, you can.

@andrewgodwin Thank you for your patience, maybe something related to these two issues in https://github.com/django/channels/issues/1576 and https://github.com/django/channels/issues/1491.

looks like there is a problem with the combination of channels3(asgiref3.3.x)+django3.

I’ll try to reproduce it in a minimal sample project.

[dacevedo12]

Just wanted to confirm that after downgrading to 3.2.10 the problem disappeared 🎉