On Aug 18, 1:10 pm, 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: > > Thanks > > -=-=-=-=- > > #!/usr/bin/python > > import thread, sys, time > > def busy(thread): > x=0 > while True: > x+=1 > > if __name__ == '__main__': > try: > cpus = int(sys.argv[1]) > except ValueError: > cpus = 1 > print "cpus = %d, argv[1] = %s\n" % (cpus, sys.argv[1]) > i=0 > thread_list = [] > while i < cpus: > x = thread.start_new_thread(busy, (i,)) > thread_list.append(x) > i+=1 > while True: > pass > > -- > Derek D. Martinhttp://www.pizzashack.org/ > GPG Key ID: 0x81CFE75D > > application_pgp-signature_part > < 1KViewDownload
watch this and all your findings will be explained: http://blip.tv/file/2232410 this talk marked a pivotal moment in my understanding of python threads and signal handling in threaded programs. -- http://mail.python.org/mailman/listinfo/python-list
