Mail Archives: cygwin/2011/08/03/03:50:48
Hi Jason,
it looks like there's a build glitch in python:
$ cat > sel.py <<EOF
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)
EOF
$ python sel.py
socket opened with fd 3
socket opened with fd 4
socket opened with fd 5
[...]
socket opened with fd 62
socket opened with fd 63
socket opened with fd 64
socket opened with fd 64
Traceback (most recent call last):
File "test.py", line 10, in <module>
select(ins, [], [], 0)
ValueError: filedescriptor out of range in select()
I debugged this and it turns out that python does not call Cygwin's
select function anymore, as soon as there's a file descriptor in the
set which is >= 64.
While the default value for FD_SETSIZE is 64 (see /usr/include/sys/types.h):
# ifndef FD_SETSIZE
# define FD_SETSIZE 64
AFAICS the python default for the fd set is 256, see the definition
in /usr/include/python2.6/pyport.h:
#ifndef FD_SETSIZE
#define FD_SETSIZE 256
But somehow this didn't make it into the python build. On my Linux
box, the same script only stops when it hits the soft descriptor
limit, 1024 in my case.
Can you have a look and, perhaps, provide a new python with a bigger
internal FD_SETSIZE? The 256 from /usr/include/python2.6/pyport.h
would already be ok, I guess, but 512 or so wouldn't hurt either...
Thanks,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Red Hat
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