New submission from greg.ath <gathan...@gmail.com>:
Hi,
My multithreaded application uses multithreading.Value() to ensure thread-safe
operations on shared data.
For unexpected reasons, after some change in my code, the function will
consistently hang.
I did a gdb backtrace of the hanging process, and I discovered that the
multiprocessing.head.py tries to acquire twice a same non recursive lock.
The first aquire is done in the "malloc" function:
#61 call_function (f=
Frame 0x13be190, for file /usr/lib/python2.6/multiprocessing/heap.py, line
173, in malloc (self=<Heap(_stop_to_block={}, _lengths=[], _lock=<thread.lock
at remote 0x7f00fc770eb8>, _allocated_blocks=set([...
The second aquire is done in the "free" function:
#3 0x00000000004a7c5e in call_function (f=
Frame 0x1662d50, for file /usr/lib/python2.6/multiprocessing/heap.py, line
155, in free (self=<Heap(_stop_to_block={}, _lengths=[], _lock=<thread.lock at
remote 0x7f00fc770eb8>, _allocated_blocks=set([...
I don't understand the link between these two method calls, so I am unable to
write an easy script to reproduce the problem. I would say that some garbage
collection was done within the malloc, which called the free.
Python 2.6.5
Linux dev 2.6.32-25-server #45-Ubuntu SMP Sat Oct 16 20:06:58 UTC 2010 x86_64
GNU/Linux
----------
components: None
files: gdb_stack.txt
messages: 138506
nosy: greg.ath
priority: normal
severity: normal
status: open
title: multiprocessing.Value() hangs
type: behavior
versions: Python 2.6
Added file: http://bugs.python.org/file22393/gdb_stack.txt
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<http://bugs.python.org/issue12352>
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