pythonの递归锁

首先看一个例子，让我们lock = threading.Lock() 时（代码第33行），程序会卡死在这里

#!/usr/bin/env python
import threading,time


def run1():
    print("grab the first part data")
    # 申请锁
    lock.acquire()
    # 将全局的变量，在此声明一下
    global  num
    num += 1
    # 释放锁
    lock.release()
    return  num
def run2():
    print("grab the second part data")
    lock.acquire()
    global  num2
    num2 += 1
    lock.release()
    return  num2
def run3():
    lock.acquire()
    res = run1()
    print("between run1 and run2")
    res2 = run2()
    lock.release()
    print(res,res2)

if __name__ == "__main__":
    num,num2 = 0,0
    # 递归锁
    lock = threading.Lock()
    for i in range(10):
        t = threading.Thread(target=run3)
        t.start()

while threading.active_count() != 1:
    print(threading.active_count())

else:
    print("all threads done")
    print(num,num2)

如果我们将其改为lock = threading.RLock()，那么程序就能正常运行，这个就是递归锁  RLock()

#!/usr/bin/env python
import threading,time


def run1():
    print("grab the first part data")
    # 申请锁
    lock.acquire()
    # 将全局的变量，在此声明一下
    global  num
    num += 1
    # 释放锁
    lock.release()
    return  num
def run2():
    print("grab the second part data")
    lock.acquire()
    global  num2
    num2 += 1
    lock.release()
    return  num2
def run3():
    lock.acquire()
    res = run1()
    print("between run1 and run2")
    res2 = run2()
    lock.release()
    print(res,res2)

if __name__ == "__main__":
    num,num2 = 0,0
    # 递归锁
    lock = threading.RLock()
    for i in range(10):
        t = threading.Thread(target=run3)
        t.start()

while threading.active_count() != 1:
    print(threading.active_count())

else:
    print("all threads done")
    print(num,num2)