标准库模块multiprocessing（六）--进程锁（Lock）--互斥机制

1、创建对象

　　lock = Lock()

2、lock.acquire()   

　　上锁

3、lock.release()

　　 解锁  #如果一个锁对象已经被上锁则再调用acquire会阻塞

4、with lock ：          上锁

　　 ....

　　....

　　解锁

 

【上锁+解锁】
from  multiprocessing import Process,Lock 
import sys 
from time import sleep 

#sys.stdout作为标准输出流是多个进程共有的资源

def writer1():
    lock.acquire()  #上锁
    for i in range(5):
        sleep(1)
        sys.stdout.write("writer1输出\n")
    lock.release() #解锁

def writer2():
    with lock:
        for i in range(5):
            sleep(1)
            sys.stdout.write("writer2输出\n")

#创建锁
lock = Lock()

w1 = Process(target = writer1)
w2 = Process(target = writer2)

w1.start()
w2.start()

w1.join()
w2.join()

#结果
writer1输出
writer1输出
writer1输出
writer1输出
writer1输出
writer2输出
writer2输出
writer2输出
writer2输出
writer2输出

 

【上锁+不解锁】
from  multiprocessing import Process,Lock
import sys
from time import sleep

#sys.stdout作为标准输出流是多个进程共有的资源

def writer1():
    lock.acquire()  #上锁
    for i in range(5):
        sleep(1)
        sys.stdout.write("writer1输出\n")
    #lock.release() #解锁

def writer2():
    with lock:
        for i in range(5):
            sleep(1)
            sys.stdout.write("writer2输出\n")

#创建锁
lock = Lock()

w1 = Process(target = writer1)
w2 = Process(target = writer2)

w1.start()
w2.start()

w1.join()
w2.join()

#结果
writer1输出
writer1输出
writer1输出
writer1输出
writer1输出
（阻塞...）

 

【不加锁】
from  multiprocessing import Process,Lock
import sys
from time import sleep

#sys.stdout作为标准输出流是多个进程共有的资源

def writer1():
    #lock.acquire()  #上锁
    for i in range(5):
        sleep(1)
        sys.stdout.write("writer1输出\n")
    #lock.release() #解锁

def writer2():
    with lock:
        for i in range(5):
            sleep(1)
            sys.stdout.write("writer2输出\n")

#创建锁
lock = Lock()

w1 = Process(target = writer1)
w2 = Process(target = writer2)

w1.start()
w2.start()

w1.join()
w2.join()

#结果
writer1输出
writer2输出
writer1输出
writer2输出
writer1输出
writer2输出
writer1输出
writer2输出
writer1输出
writer2输出