Python學習筆記：同步鎖

# -*- encoding:utf-8 -*-
import threading
import time

def sub():
    global num
    # num-=1
    lock.acquire()  #獲取鎖，將lock中間包起來，執行中間部分的時候cpu不準輪詢，只能串行
    temp=num
    time.sleep(0.001)
    num=temp-1
    lock.release()  #釋放鎖

num=100

l=[]
lock=threading.Lock()
for i in range(100):
    t=threading.Thread(target=sub)
    t.start()
    l.append(t)

for t in l:
    t.join()

print (num)