from multiprocessing import Pool
import os
import time
import random
import multiprocessing
def task(name):
print('run task %s (%s)' % (name, os.getpid()))
start = time.time()
time.sleep(random.random() * 5 + 1)
end = time.time()
print('task %s run %0.f seconds' % (name, end - start))
if __name__ == '__main__':
print('parenet process: %s' % os.getpid())
p = Pool(processes=4)
print('pool size: %s' % p._processes)
p._processes = 6
print('pool size: %s' % p._processes)
for i in range(5):
p.apply_async(task, args=(i,))
print('waiting for all processes done....')
p.close()
p.join()
print('all process done.')
