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Title: PyGILState_Ensure() deadlocks (ver 2.4)
Type: Stage:
Components: Interpreter Core Versions:
Status: closed Resolution: not a bug
Dependencies: Superseder:
Assigned To: Nosy List: andivajda, mwh, tim.peters
Priority: normal Keywords:

Created on 2004-11-30 01:54 by andivajda, last changed 2022-04-11 14:56 by admin. This issue is now closed.

File name Uploaded Description Edit andivajda, 2004-12-04 03:10 a PyLucene unit test that locks up easily
Messages (6)
msg23367 - (view) Author: Andi Vajda (andivajda) Date: 2004-11-30 01:54
PyLucene ( wraps
libgcj with python. Python objects are also wrapped by
java objects. The ref count of the python is
incremented in the wrapping java object constructor and
is decremented in the wrapping java object's finalize()
method. Yes, finalize() is not a reliable means of
cleaning memory up but, so far, I wasn't able to figure
out a better way to do this. The finalize() method runs
in its own libgcj finalizer thread.
It has to acquire the GIL before it can call
Py_DECREF() is my understanding. The java finalize()
calls this code in PyLucene:

void finalizeObject(PyObject *object)
#if PY_VERSION_HEX >= 0x02040000
    PyGILState_STATE state = PyGILState_Ensure();


When compiled with python 2.4c1, this mostly works.
Except that it deadlocks, every now and then. If I
comment this code out, no deadlock. I also verified
that the finalizer is called at most once per such
object. I realize that reproducing this bug maybe hard,
building PyLucene is not particularly easy, unless you
have gcj ready.
If you contact me, I'm more than willing to help in
providing all that's needed to reproduce this. I've
seen the deadlock on Mac OS X 10.3.6, my main
development OS.
For what it's worth, I also tried this with python
2.3.4 (including threadmodule.c patch made in
September, related to GIL function usage).
msg23368 - (view) Author: Andi Vajda (andivajda) Date: 2004-12-04 03:10
Logged In: YES 

I verified this now with python 2.4 final. It still happens
as tested on Mac OS X.
I was also able to narrow it down to a unit test, that when
run repeatedly will eventually lock up. It is attached.
If you need assistance building PyLucene from sources, or
want me to provide a binary, let me know. At the moment, to
reproduce this bug, it is best to build PyLucene from
See for more information.
msg23369 - (view) Author: Andi Vajda (andivajda) Date: 2004-12-04 03:42
Logged In: YES 

I've been running the same test loop on Gentoo/2.6/python
2.4 and was not able to get it to deadlock so far. This bug
could be limited to Mac OS X.
msg23370 - (view) Author: Andi Vajda (andivajda) Date: 2004-12-05 04:15
Logged In: YES 

I finally tracked down this bug to gcj bug <a
which is fixed in gcj version >= 3.4.2.
I am hence closing this python bug as invalid.
msg23371 - (view) Author: Michael Hudson (mwh) (Python committer) Date: 2004-12-05 10:35
Logged In: YES 

Speaking as a Python developer, phew :)
msg23372 - (view) Author: Tim Peters (tim.peters) * (Python committer) Date: 2004-12-19 04:19
Logged In: YES 

Changed Group to 3rdParty.
Date User Action Args
2022-04-11 14:56:08adminsetgithub: 41245
2004-11-30 01:54:36andivajdacreate