18-08-2009 o 22:10:15 Derek Martin <c...@pizzashack.org> wrote:
I have some simple threaded code... If I run this with an arg of 1 (start one thread), it pegs one cpu, as I would expect. If I run it with an arg of 2 (start 2 threads), it uses both CPUs, but utilization of both is less than 50%. Can anyone explain why? I do not pretend it's impeccable code, and I'm not looking for a critiqe of the code per se, excepting the case where what I've written is actually *wrong*. I hacked this together in a couple of minutes, with the intent of pegging my CPUs. Performance with two threads is actually *worse* than with one, which is highly unintuitive. I can accomplish my goal very easily with bash, but I still want to understand what's going on here... The OS is Linux 2.6.24, on a Ubuntu base. Here's the code:
Python threads can't benefit from multiple processors (because of GIL, see: http://docs.python.org/glossary.html#term-global-interpreter-lock). 'multiprocessing' module is what you need: http://docs.python.org/library/multiprocessing.html Cheers, *j -- Jan Kaliszewski (zuo) <z...@chopin.edu.pl> -- http://mail.python.org/mailman/listinfo/python-list
