A couple years ago I did some work on enabling multi-threading in the
PIL core library, with the help of Fredrik and others. We
successfully implemented it by releasing the GIL prior to starting
many of the larger routines/functions in the C library, and re-
acquiring it before handing back to the wrappers. I can't remember
exactly which functions we did this to in total, but it definitely
included the Image.resize code and so forth. On my dual-processor
machine, I saw almost double performance on multi-threaded resizing
operations - proving it worked. However, we never touched the pixel
access sections.
You could look at the resize code in the C module and use the same
method to try it with the functions you use most. The trick is just
figuring out the right places to release and recapture the GIL.
Kevin.
On 06 Aug 2008, at 21:01, Sebastian Haase wrote:
For pixel-by-pixel stuff you would probably be much (!) faster using
numpy.
- Sebastian Haase
On Wed, Aug 6, 2008 at 7:49 PM, Stani <[EMAIL PROTECTED]> wrote:
Op woensdag 06-08-2008 om 09:45 uur [tijdzone -0600], schreef
Kristofor
Amundson:
My problem is that I see little to no improvement in my performance
with the threading, even when I process the images on a machine
with 8
CPU's. In fact, it only seems to utilize one CPU. Is this due to the
GIL?
Probably so.
I am wondering if there is a way for me to properly thread this to
improve my performance.
I use mostly subprocess pools to increase multi-core performance,
but of
course this might be not evident to implement depending on the
specifics
of your software. That is the only way to take advantage of multi-
core
CPU (or of course stackless python).
To speed up your existing code, you might also give psyco a try
(which
is again in active development), profile your code and rewrite some
parts in cython or wait for PyPy to mature.
Stani
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_______________________________________________
Image-SIG maillist - Image-SIG@python.org
http://mail.python.org/mailman/listinfo/image-sig
_______________________________________________
Image-SIG maillist - Image-SIG@python.org
http://mail.python.org/mailman/listinfo/image-sig
