python3 线程死锁

所谓死锁：是指两个或两个以上的进程或线程在执行过程中，因争夺资源而造成的一种互相等待的现象，若无外力作用，它们都将无法推进下去。此时称系统处于死锁状态或系统产生了死锁，这些永远在互相等待的进程称为死锁进程，如下就是死锁

code

from threading import Thread,Lock
import time

mutexA=Lock()
mutexB=Lock()

class MyThread(Thread):
    def run(self):
        self.func1()
        self.func2()

    def func1(self):
        mutexA.acquire()
        print('\033[41m%s 拿到A锁\033[0m' %self.name)

        mutexB.acquire()
        print('\033[42m%s 拿到B锁\033[0m' %self.name)
        mutexB.release()
        print('\033[42m%s 解B锁\033[0m' %self.name)

        mutexA.release()
        print('\033[42m%s 解A锁\033[0m' %self.name)

    def func2(self):
        mutexB.acquire()
        print('\033[43m%s 拿到B锁\033[0m' %self.name)
        time.sleep(2)

        mutexA.acquire()
        print('\033[44m%s 拿到A锁\033[0m' %self.name)
        mutexA.release()
        print('\033[42m%s 解A锁\033[0m' %self.name)

        mutexB.release()
        print('\033[42m%s 解B锁\033[0m' %self.name)

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

outputs

macname@MacdeMacBook-Pro py % python3 cccccc.py
Thread-1 拿到A锁
Thread-1 拿到B锁
Thread-1 解B锁
Thread-1 解A锁
Thread-1 拿到B锁
Thread-2 拿到A锁
^CException ignored in: <module 'threading' from '/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/threading.py'>
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/threading.py", line 1308, in _shutdown
    lock.acquire()
KeyboardInterrupt
macname@MacdeMacBook-Pro py %

线程1拿到A以及B后，再次释放

接下来，由于线程2抢到了A锁，线程1抢到了B锁

相互等待，两个线程都无法继续执行