RuntimeError on windows trying python multiprocessing -

i trying first formal python program using threading , multiprocessing on windows machine. unable launch processes though, python giving following message. thing is, not launching threads in main module. threads handled in separate module inside class.

edit: way code runs fine on ubuntu. not quite on windows

runtimeerror:              attempt start new process before current process             has finished bootstrapping phase.             means on windows , have             forgotten use proper idiom in main module:                 if __name__ == '__main__':                     freeze_support()                     ...             "freeze_support()" line can omitted if program             not going frozen produce windows executable. 

my original code pretty long, able reproduce error in abridged version of code. split in 2 files, first main module , little other import module handles processes/threads , calls method. second module meat of code is.

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testmain.py:

import paralleltestmodule  extractor = paralleltestmodule.parallelextractor() extractor.runinparallel(numprocesses=2, numthreads=4) 

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paralleltestmodule.py:

import multiprocessing multiprocessing import process import threading  class threadrunner(threading.thread):     """ class represents single instance of running thread"""     def __init__(self, name):         threading.thread.__init__(self)         self.name = name     def run(self):         print self.name,'\n'  class processrunner:     """ class represents single instance of running process """     def runp(self, pid, numthreads):         mythreads = []         tid in range(numthreads):             name = "proc-"+str(pid)+"-thread-"+str(tid)             th = threadrunner(name)             mythreads.append(th)          in mythreads:             i.start()         in mythreads:             i.join()  class parallelextractor:         def runinparallel(self, numprocesses, numthreads):         myprocs = []         prunner = processrunner()         pid in range(numprocesses):             pr = process(target=prunner.runp, args=(pid, numthreads))              myprocs.append(pr)  #        if __name__ == 'paralleltestmodule':    #this didnt work #        if __name__ == '__main__':              #this doesnt work #        multiprocessing.freeze_support()        #added after seeing error no avail         in myprocs:             i.start()          in myprocs:             i.join() 

on windows subprocesses import (i.e. execute) main module @ start. need protect main code avoid creating subprocesses recursively:

import paralleltestmodule  if __name__ == '__main__':         extractor = paralleltestmodule.parallelextractor()     extractor.runinparallel(numprocesses=2, numthreads=4)