python Lock、RLock

Lock: 只能acquire一次，下一次acquire必须release后才能，不然会造成死锁

from threading import Lock

total = 0
lock = Lock()
def add():
    #1. dosomething1
    #2. io操作
    # 1. dosomething3
    global lock
    global total
    for i in range(1000000):
        lock.acquire()
        total += 1
        lock.release()

def desc():
    global total
    global lock
    for i in range(1000000):
        lock.acquire()
        total -= 1
        lock.release()

import threading
thread1 = threading.Thread(target=add)
thread2 = threading.Thread(target=desc)
thread1.start()
thread2.start()

#
thread1.join()
thread2.join()
print(total)

RLock: 在同一个线程里面，可以连续调用多次acquire， 一定要注意acquire的次数要和release的次数相等

from threading import  RLock
total = 0
lock = RLock()
def add():
    #1. dosomething1
    #2. io操作
    # 1. dosomething3
    global lock
    global total
    for i in range(1000000):
        lock.acquire()
        lock.acquire()
        total += 1
        lock.release()
        lock.release()

def desc():
    global total
    global lock
    for i in range(1000000):
        lock.acquire()
        total -= 1
        lock.release()

import threading
thread1 = threading.Thread(target=add)
thread2 = threading.Thread(target=desc)
thread1.start()
thread2.start()

#
thread1.join()
thread2.join()
print(total)