进程共用变量

from multiprocessing import Pool
import time, os

def foo(i):
    print('Run task %s (%s)...' % (i, os.getpid()))
    start = time.time()
    time.sleep(1)
    end = time.time()
    print('Task %s runs %0.2f seconds.' % (i, (end - start)))

if __name__=='__main__':
    print('Parent process %s.' % os.getpid())
    p = Pool(4)
    for i in range(5):
        p.apply_async(foo, args=(i,))
    print('Waiting for all subprocesses done...')
    p.close()
    p.join()
    print('All subprocesses done.')