# practice :
import time
from multiprocessing import Pool
def run(fn):
#fn: A function parameter is an element of a data list
time.sleep(1)
return fn * fn if __name__ == "__main__":
testFL = [1,2,3,4,5,6]
print 'Single process execution sequence:' # Sequential execution ( Serial execution , Single process )
s = time.time()
for fn in testFL:
run(fn) e1 = time.time()
print u" Sequence execution time :", int(e1 - s) print 'concurrent:' # Create multiple processes , Parallel execution
pool = Pool(5) # Create ownership 5 Process pool of number of processes
#testFL: List of data to process ,run: Handle testFL Functions for the data in the list
rl =pool.map(run, testFL)
pool.close()# Close process pool , No more new assignments
pool.join()# The main process is blocked waiting for the child process to exit
e2 = time.time()
print u" Parallel execution time :", int(e2 - e1)
print rl # practice :
from multiprocessing import Process, Queue
import os, time, random # Write code executed by data process :
def write(q):
for value in ['A', 'B', 'C']:
print 'Put %s to queue...' % value
q.put(value)
time.sleep(random.random()) # Read code executed by data process
def read(q):
time.sleep(1)
while not q.empty():
# if not q.empty():
print 'Get %s from queue.' % q.get(True)
time.sleep(1) # The goal is to wait for the write queue to complete if __name__=='__main__':
# Parent process creation Queue, And passed to all subprocesses
q = Queue()
pw = Process(target = write, args = (q,))
pr = Process(target = read, args = (q,))
# Start subprocess pw, write in :
pw.start()
# Start subprocess pr, Read :
pr.start()
# wait for pw end :
pw.join()
pr.join()
print “Done!”

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