[Python-Dev] Different cpu python code usage between embedded mode and standalone mode (original) (raw)

Pau Freixes pfreixes at gmail.com
Sat Jun 7 19:14:36 CEST 2008

Hi list,

First Hello to all, I have a serious problem for understand some results when I'm comparing cpu usages between same python code in embedded mode and standalone mode ( python name_script.py )

This last months I have been writing 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

_nrdigest = 0 _const_b = 20 _f = None _signal = False

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()

Define entry point with one input variable

req is a instance of Request object, usefull members of this object are:

req.input is a dictionary with input.xml variables

req.constants is a dictionary with constants defined into signature.xml

req.output is void dictionary for full with output variables

req.config is a dictionary with config values take from namespace

req.apdn_pid is a pid of aplication

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 md5challenge reached 1.000.000 milion keys in 10 seconds but when i try to run this code 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 !!!

The alarm time expires in both case in 10 seconds.

Thks to all, can anybody help to me for understand this results ?

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