python 进程池Pool

#-*- coding:utf-8 -*-
from multiprocessing import Pool
import os,time,random

def long_time_task(name):
    print 'Run task name %s and pid : %s..'%(name,os.getpid())
    start = time.time()
    time.sleep(random.random()*3)
    end = time.time()
    print 'Task %s betwine %s '%(name,(end-start))
#    pass
if __name__ == '__main__':
    print 'Parent process %s.'%os.getpid()
    p=Pool()
    for i in range(5):
        print 'now I is ' and i
        print 'Parent process %s.'%os.getpid()
        p.apply_async(long_time_task,args=(i,))
    print 'Wait for all subprocesses done...'
    print (i,)
    p.close()
    p.join()
    print 'All over'

结果（类）：

Parent process 3896.
0
Parent process 3896.
1
Parent process 3896.
2
Parent process 3896.
3
Parent process 3896.
4
Parent process 3896.
Wait for all subprocesses done...
(4,)
Run task name 0 and pid : 4300..
Run task name 1 and pid : 4596..
Task 1 betwine 1.32100009918
Run task name 2 and pid : 4596..
Task 0 betwine 2.61500000954
Run task name 3 and pid : 4300..
Task 2 betwine 2.65400004387
Run task name 4 and pid : 4596..
Task 4 betwine 0.599999904633
Task 3 betwine 2.77799987793
All over