gh-80184: Set getattr(socket, "SOMAXCONN", 5) as the default queue size for TCPServer

[sahilds1]

• Issue: set better defaults for TCPServer options #80184

[python-cla-bot]

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[bedevere-app]

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[picnixz]

Thanks for the PR, but we should add a NEWS entry as well as a .. versionchanged:: next in the rst docs of TCPServer.

[gpshead]

Okay, i this change looks right for what was described in the issue. BUT i've done a little more research to double check the implications. we may not want to use 0 even though that felt right. apparently some platforms treat that as actual 0, effectively disabling connections. posix doesn't seem to require 0 to mean "default". ugh.

In particular Linux - https://bugzilla.kernel.org/show_bug.cgi?id=119141

a better alternative effectively similar to what the intent of 0 was is probably something like:

getattr(socket, "SOMAXCONN", 5) to use socket.SOMAXCONN if defined otherwise our old non-zero default.