[Python-Dev] Pervasive socket failures on Windows

Tim Peters tim.peters at gmail.com
Fri Feb 10 22:55:18 CET 2006

[Martin v. Löwis]
>>> So FD_SETSIZE is 64 on Windows,

[Tim Peters]
>> In Python FD_SETSIZE is 512 on Windows (see the top of selectmodule.c).

[Scott Dial]
> Although I agree, in terms of the socketmodule, there was no such define
> overriding the default FD_SETSIZE, so you are both right.

?  Sorrry, don't know what you're talking about here.  Python's
selectmodule.c #defines FD_SETSIZE before it includes winsock.h on
Windows, so Microsoft's default is irrelevant to Python.  The reason
selectmodule.c uses "!defined(FD_SETSIZE)" in its

#if defined(MS_WINDOWS) && !defined(FD_SETSIZE)
#define FD_SETSIZE 512

is explained in the comment right before that code.

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