RuntimeError on windows trying python multiprocessing

RuntimeError on windows trying python multiprocessing

I am trying my very first formal python program using Threading and
Multiprocessing on a windows machine. I am unable to launch the processes
though, with python giving the following message. The thing is, I am not
launching my threads in the main module. The threads are handled in a
separate module inside a class.
RuntimeError:
Attempt to start a new process before the current process
has finished its bootstrapping phase.
This probably means that you are on Windows and you have
forgotten to use the proper idiom in the main module:
if __name__ == '__main__':
freeze_support()
...
The "freeze_support()" line can be omitted if the program
is not going to be frozen to produce a Windows executable.
My original code is pretty long, but I was able to reproduce the error in
an abridged version of the code. It is split in two files, the first is
the main module and does very little other than import the module which
handles processes/threads and calls a method. The second module is where
the meat of the code is.



testMain.py:
import parallelTestModule
extractor = parallelTestModule.ParallelExtractor()
extractor.runInParallel(numProcesses=2, numThreads=4)



parallelTestModule.py:
import multiprocessing
from multiprocessing import Process
import threading
class ThreadRunner(threading.Thread):
""" This class represents a single instance of a running thread"""
def __init__(self, name):
threading.Thread.__init__(self)
self.name = name
def run(self):
print self.name,'\n'
class ProcessRunner:
""" This class represents a single instance of a running process """
def runp(self, pid, numThreads):
mythreads = []
for tid in range(numThreads):
name = "Proc-"+str(pid)+"-Thread-"+str(tid)
th = ThreadRunner(name)
mythreads.append(th)
for i in mythreads:
i.start()
for i in mythreads:
i.join()
class ParallelExtractor:
def runInParallel(self, numProcesses, numThreads):
myprocs = []
prunner = ProcessRunner()
for 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 obviously doesnt work
# multiprocessing.freeze_support() #added after seeing error
to no avail
for i in myprocs:
i.start()
for i in myprocs:
i.join()