# CS 450; Python Process pool example
# version 2014-01-31 8:37 PM
#
# Create a pool of processes; then create a number of
# processes and run them from the pool.
#
from multiprocessing import Pool
import os, random, time

# This time, say hello prints out the id and returns
# its process id. To make it easier (?) to read the
# output, the messages about the child running /
# finishing have >'s prepended when we start and <'s
# when we finish.
#
def say_hello(id):
	print(id*'>' + ' Child {} is running'.format(id))
	time.sleep(1/random.randint(1,9))
	print(id*'<' + ' Child {} is finished'.format(id))
	return os.getpid()

# Create a number of say hello processes and run them
# using the pool of available processes.  We print
# out a list of the process ids used. Note the number
# of distinct process ids = poolsize.
#
def main(poolsize=2, nbr_procs=8):
	pool = Pool(processes = poolsize);
	print(pool.map(say_hello, range(nbr_procs)))
	pool.close()	# Start cleanup
	pool.join()		# Wait for cleanup to finish

main()