python seems to be built with the default value of FD_SETSIZE, which is only
64 on cygwin.
I noticed this as it causes numerous tests in the twisted test suite to fail
with "ValueError: filedescriptor out of range in select()" exceptions, but can
also be demonstrated with a simple test case:
$ cat select_test.py
from socket import *
from select import select
ins = []
for i in range(1024):
s = socket(AF_INET, SOCK_STREAM)
ins.append(s)
print "socket opened with fd", s.fileno()
select(ins, [], [], 0)
$ python select_test.py
[...]
socket opened with fd 64
Traceback (most recent call last):
File "./select_test.py", line 11, in <module>
select(ins, [], [], 0)
ValueError: filedescriptor out of range in select()
Looking at the source [1], note that steps are already taken to increase the
default value of FD_SETSIZE on Win32, and I'd suggest it's appropriate to do
the same on cygwin, patch attached.
Note some code motion is necessary as FD_SETSIZE must be defined before
sys/types.h is included if we are going to override the default value set there.
I don't believe this can cause any ABI issues as the interface is in terms of
python lists, rather than fd_set values.
[1] http://hg.python.org/cpython/file/3c0edb157ea2/Modules/selectmodule.c
--- origsrc/Python-2.6.5/Modules/selectmodule.c 2009-10-27 15:39:53.000000000
+0000
+++ src/Python-2.6.5/Modules/selectmodule.c 2011-03-14 18:25:48.859375000
+0000
@@ -6,6 +6,21 @@
>= 0.
*/
+/* Windows #defines FD_SETSIZE to 64 if FD_SETSIZE isn't already defined.
+ 64 is too small (too many people have bumped into that limit).
+ Here we boost it.
+
+ Cygwin also defines FD_SETSIZE to 64, so also increase the limit on
+ Cygwin. We must do this before sys/types.h is included, which otherwise
+ sets FD_SETSIZE to the default.
+
+ Users who want even more than the boosted limit should #define
+ FD_SETSIZE higher before this; e.g., via compiler /D switch.
+*/
+#if (defined(MS_WINDOWS) || defined(__CYGWIN__)) && !defined(FD_SETSIZE)
+#define FD_SETSIZE 512
+#endif
+
#include "Python.h"
#include <structmember.h>
@@ -16,16 +31,6 @@
#undef HAVE_BROKEN_POLL
#endif
-/* Windows #defines FD_SETSIZE to 64 if FD_SETSIZE isn't already defined.
- 64 is too small (too many people have bumped into that limit).
- Here we boost it.
- Users who want even more than the boosted limit should #define
- FD_SETSIZE higher before this; e.g., via compiler /D switch.
-*/
-#if defined(MS_WINDOWS) && !defined(FD_SETSIZE)
-#define FD_SETSIZE 512
-#endif
-
#if defined(HAVE_POLL_H)
#include <poll.h>
#elif defined(HAVE_SYS_POLL_H)
--
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