Bugs item #1590864, was opened at 2006-11-05 11:06
Message generated for change (Settings changed) made by akuchling
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1590864&group_id=5470
Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: Python Library
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Michael Tsai (michaeltsai)
>Assigned to: Peter Åstrand (astrand)
Summary: subprocess deadlock
Initial Comment:
When I use subprocess.py from a child thread, sometimes it deadlocks. I
determined that the new process is blocked during an import:
#0 0x90024427 in semaphore_wait_signal_trap ()
#1 0x90028414 in pthread_cond_wait ()
#2 0x004c77bf in PyThread_acquire_lock (lock=0x3189a0, waitflag=1)
at Python/thread_pthread.h:452
#3 0x004ae2a6 in lock_import () at Python/import.c:266
#4 0x004b24be in PyImport_ImportModuleLevel (name=0xaad74 "errno",
globals=0xbaed0, locals=0x502aa0, fromlist=0xc1378, level=-1) at
Python/import.c:2054
#5 0x0048d2e2 in builtin___import__ (self=0x0, args=0x53724c90,
kwds=0x0) at Python/bltinmodule.c:47
#6 0x0040decb in PyObject_Call (func=0xa94b8, arg=0x53724c90,
kw=0x0) at Objects/abstract.c:1860
and that the code in question is in os.py:
def _execvpe(file, args, env=None):
from errno import ENOENT, ENOTDIR
I think the problem is that since exec (the C function) hasn't yet been
called in the new process, it's inherited from the fork a lock that's already
held. The main process will eventually release its copy of the lock, but this
will not unlock it in the new process, so it deadlocks.
If I change os.py so that it imports the constants outside of
_execvpe, the new process no longer blocks in this way.
This is on Mac OS X 10.4.8.
----------------------------------------------------------------------
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1590864&group_id=5470
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
