ValueError: filedescriptor out of range in select()

[julianofischer]

What does this PR do?

This PR replaces the use of select.select() in the recv() method with the higher-level selectors API (selectors.DefaultSelector), eliminating the fixed FD_SETSIZE limit. Specifically, when timeout == 0, it now:

Registers the socket for read events on a DefaultSelector

Calls selector.select(timeout=0) instead of select.select([...], [], [], 0)

Processes any ready file descriptors directly from the selector results

By using selectors, the code automatically leverages the best available backend (epoll, kqueue, poll, etc.) and lifts the file-descriptor range restriction, preventing the “filedescriptor out of range in select()” errors on systems with high FD numbers.

What issues does this PR fix or reference?

#65878
#63404

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes/No

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[twangboy]

Could we get a changelog and a test for this change?

[julianofischer]

@dwoz @twangboy Amazon Linux 2023 scenarios zeromq is exiting with code 143, which probably means it is exceeding resource consumption.

  ..................................  System  -  CPU:  93.30 %   MEM:  98.70 % (Virtual Memory)  SWAP:  97.50 %
  ..........................  Test Suite Run  -  CPU: 114.80 %   MEM:  87.01 % (RSS)   MEM SUM:  93.26 % (RSS)   CHILD PROCS: 14
  ...  SaltMaster(id='reauth-master-fAPyzU')  -  CPU:   0.00 %   MEM:   0.50 % (RSS)   MEM SUM:   6.25 % (RSS)   CHILD PROCS: 13

Unless this is part of the test, we could try:

• increasing timeout
• reduce the number of parallel tests

Let me know if you need my assistance here.

[welcome]

Congratulations on your first PR being merged! 🎉