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)