dictionary changed size during iteration

Hi there!

I’ve just upgraded from cheroot==8.4.4 to cheroot==8.4.5 and I noticed what looks like a regression.

❓ I’m submitting a …

• 🐞 bug report

🐞 Describe the bug. What is the current behavior?

I see this in my server logs:

Error in HTTPServer.tick
Traceback (most recent call last):
  File ".../lib/site-packages/cheroot/server.py", line 1798, in serve
    self.tick()
  File ".../lib/site-packages/cheroot/server.py", line 2046, in tick
    self._connections.expire()
  File ".../lib/site-packages/cheroot/connections.py", line 105, in expire
    in self._selector.get_map().items()
  File ".../lib/_abcoll.py", line 414, in items
    return [(key, self[key]) for key in self]
RuntimeError: dictionary changed size during iteration

❓ What is the motivation / use case for changing the behavior?

There is occasional log spam (for a low traffic environment), but I assume this has some other undesired side-effects…

💡 To Reproduce

I’m not sure exactly. We have a test environment with synthetic checks that does a couple requests per second and the behaviour occurs “naturally”…

📋 Details

We very recently upgraded from version 8.4.4 to 8.4.5, but it’s possible the error was already present in 8.4.4. We use pip-compile and cheroot is not pinned, so we usually get updates shortly after they are released.

📋 Environment

• Cheroot version: 8.4.5
• CherryPy version: 17.4.2 (I don’t think we really use it)
• Python version: 2.7
• OS: Windows
• Browser: requests

[AndreLouisCaron]

Thanks a lot for the fix! I’m rolling that out to our test environments and will confirm the fix later this week 😃

[jaraco]

Fix from #337 is now released as 8.4.8. Please verify the fix and report back here. Thanks!