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when use popen*() and close_fds is True, python will close unused fds. but the MAXFD is not the real max. especially in freebsd, subprocess.MAXFD=655000. so python will try to close to many fd, it's too slow, in my test on freebsd, using about 3 seconds.
poor english.
patch for 2.7 trunck:
jiangxiaobing@s7v7nislands ~/source/svn/python27 $ svn diff
Index: Lib/subprocess.py
===================================================================
--- Lib/subprocess.py	(revision 88499)
+++ Lib/subprocess.py	(working copy)
@@ -1065,11 +1065,16 @@
 
 
 def _close_fds(self, but):
+ maxfd = MAX_FD
+ try:
+ maxfd = os.dup(0) + 1
+ except:
+ pass
 if hasattr(os, 'closerange'):
 os.closerange(3, but)
- os.closerange(but + 1, MAXFD)
+ os.closerange(but + 1, maxfd)
 else:
- for i in xrange(3, MAXFD):
+ for i in xrange(3, maxfd):
 if i == but:
 continue
 try:
Index: Lib/popen2.py
===================================================================
--- Lib/popen2.py	(revision 88499)
+++ Lib/popen2.py	(working copy)
@@ -82,8 +82,13 @@
 def _run_child(self, cmd):
 if isinstance(cmd, basestring):
 cmd = ['/bin/sh', '-c', cmd]
- os.closerange(3, MAXFD)
+ maxfd = MAXFD
 try:
+ maxfd = os.dup(0) + 1
+ except:
+ pass
+ os.closerange(3, maxfd)
+ try:
 os.execvp(cmd[0], cmd)
 finally:
 os._exit(1)
patch for 3.3 truck:
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index c02fb52..98a25b3 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1112,8 +1112,14 @@ class Popen(object):
 if fd >= start_fd:
 os.closerange(start_fd, fd)
 start_fd = fd + 1
- if start_fd <= MAXFD:
- os.closerange(start_fd, MAXFD)
+ maxfd = MAXFD
+ try:
+ maxfd = os.dup(0) + 1
+ except:
+ pass
+
+ if start_fd <= maxfd:
+ os.closerange(start_fd, maxfd)
 
 
 def _execute_child(self, args, executable, preexec_fn, close_fds,