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Python:cProfile

lastmod 2019-04-12created 2019-04-105 edits

Synopsis 

$ python -m cProfile [-o output_file] [-s sort_order] (-m module | myscript.py)

Simple example

It can be called from within code or from the interpreter: 

import cProfile
cProfile.run('foo()')

You can also invoke cProfile when running a script: 

$ python -m cProfile -s cumtime myscript.py

Subprocesses

The things are bit more complicated if your script starts any subprocesses. In my case, I was not interested in the main script - all it does is spawning some worker subprocesses. I was interested on what’s going on inside the workers.

Let say your code is similar to this: 

import multiprocessing
import time

def worker(num):
    time.sleep(3)
    print 'Worker:', num

if __name__ == '__main__':
    for i in range(5):
        p = multiprocessing.Process(target=worker, args=(i,))
        p.start()

You need to add another layer of indirection: 

import multiprocessing
import cProfile
import time

def worker(num):
    time.sleep(3)
    print 'Worker:', num

def profile_worker(num):
    cProfile.runctx('worker(num)', globals(), locals(), 'profile-%d.out' %num)


if __name__ == '__main__':
    for i in range(5):
        p = multiprocessing.Process(target=profile_worker, args=(i,))
        p.start()

And that is it. You’ll have profile-0.out to profile-4.out after the script is run.

See also

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