ports/132093: python's subprocess.py fails with 'Interrupted system call'

[Lapo Luchini]

>Number:         132093
>Category:       ports
>Synopsis:       python's subprocess.py fails with 'Interrupted system call'
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Feb 25 10:10:03 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Lapo Luchini
>Release:        FreeBSD 6.4-STABLE amd64
>Organization:
>Environment:
System: FreeBSD motoko.lapo.it 6.4-STABLE FreeBSD 6.4-STABLE #9: Thu Jan 29 15:50:58 CET 2009 root at motoko.lapo.it:/usr/obj/usr/src/sys/MOTOKO amd64

>Description:

Python's subprocess.py doesn't expect 'waitpid' to return 'Interrupted system call' and often fails with it.
I experienced this problem both with lang/python25 and lang/python26, but didn't check others.

>How-To-Repeat:

For example this was using devel/qct (happens very very often, making it almost unusable):

Traceback (most recent call last):
  File "/usr/local/bin/qct", line 123, in <module>
    dialog = CommitTool(vcs)
  File "/usr/local/lib/python2.6/site-packages/qctlib/gui_logic.py", line 154, in __init__
    self.__rescanFiles()
  File "/usr/local/lib/python2.6/site-packages/qctlib/gui_logic.py", line 223, in __rescanFiles
    self.itemList = self.vcs.scanFiles(self.showIgnored, pb)
  File "/usr/local/lib/python2.6/site-packages/qctlib/vcs/svn.py", line 87, in scanFiles
    statusOutput = runProgram([self.svn_exe] + extra + ['status'])
  File "/usr/local/lib/python2.6/site-packages/qctlib/utils.py", line 126, in runProgram
    code = pop.wait()
  File "/usr/local/lib/python2.6/subprocess.py", line 1137, in wait
    pid, sts = os.waitpid(self.pid, 0)
OSError: [Errno 4] Interrupted system call

>Fix:

Personally I solved my immediate problem with the following patch (retries waitpid if it was interrupted), but a more torough one can be found at this address:
http://mail.python.org/pipermail/python-dev/2004-November/049983.html

--- /usr/local/lib/python2.6/subprocess.py.orig 2009-02-17 11:34:13.000000000 +0100
+++ /usr/local/lib/python2.6/subprocess.py      2009-02-17 11:34:43.000000000 +0100
@@ -1130,11 +1130,23 @@
             return self.returncode


+        def _waitpid_no_intr(self, pid, options):
+            """Like os.waitpid, but retries on EINTR"""
+            while True:
+                try:
+                    return os.waitpid(pid, options)
+                except OSError, e:
+                    if e.errno == errno.EINTR:
+                        continue
+                    else:
+                        raise
+
+
         def wait(self):
             """Wait for child process to terminate.  Returns returncode
             attribute."""
             if self.returncode is None:
-                pid, sts = os.waitpid(self.pid, 0)
+                pid, sts = self._waitpid_no_intr(self.pid, 0)
                 self._handle_exitstatus(sts)
             return self.returncode

>Release-Note:
>Audit-Trail:
>Unformatted: