On 09/02/2009 04:51 AM, Peter Otten wrote:
tleeuwenb...@gmail.com wrote:
I have a problem using multiprocessing in a simple way. I created a
file, testmp.py, with the following contents:
---
import multiprocessing as mp
p = mp.Pool(5)
def f(x):
return x * x
print map(f, [1,2,3,4,5])
print p.map(f, [1,2,3,4,5])
I'm too lazy to read the docs, so I just tinkered:
import multiprocessing as mp
import testmp
p = mp.Pool(5)
def f(x):
return x * x
if __name__ == "__main__":
print map(f, [1,2,3,4,5])
print p.map(testmp.f, [1,2,3,4,5])
Yes, to use the multiprocessing module, you must make your script
importable, so runtime statements should go into a __main__
conditional. This way, when multiprocessing imports the module for each
of its threads, the actual runtime code only gets executed once in the
parent thread, which has the lock. At least, that is what I think is
happening.
import multiprocessing as mp
def f(x):
return x * x
if __name__ == '__main__':
p = mp.Pool(5)
print map(f, [1,2,3,4,5])
print p.map(f, [1,2,3,4,5])
http://docs.python.org/library/multiprocessing.html
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