[New-bugs-announce] [issue4738] Patch to make zlib-objects better support threads

ebfe report at bugs.python.org
Wed Dec 24 17:29:31 CET 2008

New submission from ebfe <knabberknusperhaus at yahoo.de>:

My application needs to pack and unpack workunits all day long and does
this using multiple threading.Threads. I've noticed that the zlib module
seems to use only one thread at a time when using [de]compressobj(). As
the comment in the sourcefile zlibmodule.c already says the module uses
a global lock to protect different threads from accessing the object.
While the c-functions release the GIL while waiting for the global lock,
only one thread at a time can use zlib.
My app ends up using only one CPU to compress/decompress it's workunits...

The patch (svn diff to ) attached here fixes this problem by extending
the compressobj-structure by an additional member to create
object-specific locks and removes the global lock. The lock protects
each compressobj individually and allows multiple python threads to use
zlib in parallel, utilizing all available CPUs.

components: None
files: zlib_threads.diff
keywords: patch
messages: 78266
nosy: ebfe
severity: normal
status: open
title: Patch to make zlib-objects better support threads
type: performance
versions: Python 2.5, Python 2.6, Python 2.7, Python 3.0, Python 3.1
Added file: http://bugs.python.org/file12440/zlib_threads.diff

Python tracker <report at bugs.python.org>

More information about the New-bugs-announce mailing list