Different execution time in python code between embedded or standalone

Pau Freixes pfreixes at milnou.net
Tue Jun 3 21:58:12 CEST 2008


Hi list,

First Hello to all, this is my and hope not end message to the list :P

This last months I have been writting a  program in c like to mod_python for
embedding python language, it's a middleware for dispatch and execute python
batch programs into several nodes. Now I'm writing some python program for
test how scale this into several nodes and comparing with "standalone"
performance.

I found a very strange problem with one application named md5challenge, this
aplication try to calculate the max number md5 digest in several seconds,
md5challenge use a simple signal alarm for stop program when time has
passed. This is the code of python script

def handler_alrm(signum, frame):
    global _signal
    global _nrdigest
    global _f


    _signal = True

def try_me():
    global _nrdigest
    global _f
    global _signal

    _f = open("/dev/urandom","r")
    while _signal is not True:
        buff = _f.read(_const_b)
        md5.md5(buff).hexdigest()
        _nrdigest = _nrdigest + 1

    if _f is not None :
        _f.close()

def main( req ):
    global _nrdigest


    signal.signal(signal.SIGALRM, handler_alrm)
    signal.alarm(req.input['time'])


    try_me()

    req.output['count'] = _nrdigest

    return req.OK


if __name__ == "__main__":

    # test code
    class test_req:
        pass

    req = test_req()
    req.input = { 'time' : 10 }
    req.output = { 'ret' : 0, 'count' : 0 }
    req.OK = 1

    main(req)

    print "Reached %d digests" % req.output['count']


When I try to run this program in standalone into my Pentium Dual Core
md4challenge reached 1.000.000 milion keys in 10 seconds but when i try to
run this in embedded mode md5challenge reached about 200.000 more keys !!! I
repeat this test many times and  always  wins  embedded mode  !!!  What's
happen ?

Also I tested to erase read dependencies from /dev/random, and calculate all
keys from same buffer. In this case embedded mode win always also, and the
difference are more bigger !!!

Thks to all, can anybody help to me ?
-- 
Pau Freixes
Linux GNU/User
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