Python_Multiprocessing_Start_Method.py

# Python multiprocessing - Process-based parallelism
# The following scripts are written to demonstrate multiprocessing (Process-based parallelism) 
# using Python.
# Multiprocessing is a Python package that supports spawning processes using an API similar to 
# the threading module. The multiprocessing package offers both local and remote concurrency, 
# effectively side-stepping the Global Interpreter Lock by using subprocesses instead of threads. 
# Due to this, the multiprocessing module allows the programmer to fully leverage multiple 
# processors on a given machine. It runs on both Unix and Windows.
# The multiprocessing module also introduces APIs which do not have analogs in the threading module. 
# A prime example of this is the Pool object which offers a convenient means of parallelizing the 
# execution of a function across multiple input values, distributing the input data across processes 
# (data parallelism). 
# To select a start method you use the set_start_method() in the if __name__ == '__main__' clause of 
# the main module. 
 
import multiprocessing as mp

def foo(q):

    q.put('hello')

if __name__ == '__main__':

    mp.set_start_method('spawn')

    q = mp.Queue()
    p = mp.Process(target=foo, args=(q,))

    p.start()

    print(q.get())

    p.join()