RuntimeError: set changed size during iteration

[janbuchar]

• uvloop version: 0.16.0
• Python version: 3.10.2
• Platform: 64-bit Linux
• Can you reproduce the bug with PYTHONASYNCIODEBUG in env?: not able to test
• Does uvloop behave differently from vanilla asyncio? How?: not able to test

I run a fastapi application with uvicorn, and I occassionally receive the following error:

Traceback (most recent call last):
  File "uvloop/cbhandles.pyx", line 66, in uvloop.loop.Handle._run
  File "uvloop/loop.pyx", line 473, in uvloop.loop.Loop._on_idle
  File "uvloop/loop.pyx", line 649, in uvloop.loop.Loop._exec_queued_writes
RuntimeError: set changed size during iteration

This seems to only happen in a production environment and I don't have the resources to examine it further. However, it seems that the code in the uvloop master branch is different, so maybe the error has been fixed already.

[fantix]

Thanks for the report! I can reproduce this issue, and it is a bug that sometimes happens when writing to another transport in the resume_writing() handler. I'll try to fix it and include the fix in the next release.

[janbuchar]

Thank you @fantix for resolving this so fast!