递归锁

互斥锁只能一次acquire 然后releae ，不能进行多次acquire容易出现死锁，递归锁就可以多次acquire

递归锁：递归锁可以多次进行acquire,每进行一次acquire,寄存器的基数就加1，一直等到基数变成0的时候才能被其他线程拿到

from threading import Thread,RLock
import time

class MyThread(Thread):
    def run(self):
        self.func1()
        self.func2()
    def func1(self):
        mutexA.acquire()   # +1
        print('%s 拿到A锁' %self.name)
        mutexB.acquire()  # +1=2
        print('%s 拿到B锁' %self.name)
        mutexB.release()  # -1=1
        mutexA.release()  # -1=0
    def func2(self):
        mutexB.acquire()  # +1
        print('%s 拿到B锁' %self.name)
        time.sleep(2)     # 休息
        mutexA.acquire()
        print('%s 拿到A锁' %self.name)
        mutexA.release()
        mutexB.release()

if __name__ == '__main__':
    mutexB = mutexA = RLock()
    for i in range(10):
        t=MyThread()
        t.start()