import os
import time
import random
from multiprocessing import Process,Lock
 
 
def work(lock,n):
    lock.acquire()
    print(‘%s: %s is running‘ % (n, os.getpid()))
    time.sleep(random.random())
    print(‘%s: %s is done‘ % (n, os.getpid()))
    lock.release()
if __name__ == ‘__main__‘:
    lock=Lock()
    for i in range(3):
        p=Process(target=work,args=(lock,i))
        p.start()

macname@MacdeMacBook-Pro py % python3 cccccc.py
0: 57255 is running
0: 57255 is done
1: 57256 is running
1: 57256 is done
2: 57257 is running
2: 57257 is done
macname@MacdeMacBook-Pro py %