线程_锁

#死锁：锁只能抢一次，释放后被其他人抢
from threading import Thread,Lock,current_thread
import time
class MyThread(Thread):
    def run(self):
        self.f1()
        self.f2()
    def f1(self):
        mutexA.acquire()
        print("%s 抢到A锁" %current_thread().getName())
        mutexB.acquire()
        print("%s 抢到B锁" %current_thread().getName())
        print("%s 释放B锁" %current_thread().getName())
        mutexB.release()
        print("%s 释放A锁" %current_thread().getName())
        mutexA.release()
        
    def f2(self):
        mutexB.acquire()
        print("%s 抢到B锁" %current_thread().getName())
        time.sleep(1)
        mutexA.acquire()
        print("%s 抢到A锁" %current_thread().getName())
        print("%s 释放A锁" %current_thread().getName())
        mutexA.release()
        print("%s 释放B锁" %current_thread().getName())
        mutexB.release()
        
if __name__=="__main__":
    mutexA=Lock()
    mutexB=Lock()
    for i in range(20):
        t=MyThread()
        t.start()
# '''
# Thread-758 抢到A锁
# Thread-758 抢到B锁
# Thread-758 释放B锁
# Thread-758 释放A锁
# Thread-758 抢到B锁
# Thread-759 抢到A锁
# '''
    

# 递归锁：锁可以抢多次，acquire一次，count加1,release一次，count减1，直到count=0，锁最终释放别其他人抢
from threading import Thread,RLock,current_thread
import time
class MyThread(Thread):
    def run(self):
        self.f1()
        self.f2()
    def f1(self):
        mutex.acquire()
        print("%s 抢到锁" %current_thread().getName())
        mutex.acquire()
        print("%s 抢到锁" %current_thread().getName())
        print("%s 释放锁" %current_thread().getName())
        mutex.release()
        print("%s 释放锁" %current_thread().getName())
        mutex.release()
        
    def f2(self):
        mutex.acquire()
        print("%s 抢到锁" %current_thread().getName())
        time.sleep(1)
        mutex.acquire()
        print("%s 抢到锁" %current_thread().getName())
        print("%s 释放锁" %current_thread().getName())
        mutex.release()
        print("%s 释放锁" %current_thread().getName())
        mutex.release()
        
if __name__=="__main__":
    mutex=RLock()
    for i in range(20):
        t=MyThread()
        t.start()
'''
Thread-808 抢到锁
Thread-808 抢到锁
Thread-808 释放锁
Thread-808 释放锁
Thread-810 抢到锁
Thread-810 抢到锁
Thread-810 释放锁
Thread-810 释放锁

'''

#线程：信号量【锁】

from threading import Thread,current_thread,Semaphore
import time,random
sm=Semaphore(3)
def work():
    sm.acquire()
    print("target %s is running" %current_thread().getName())
    time.sleep(random.randint(1,3))
    sm.release()
    
if __name__=="__main__":
    for i in range(10):        
        t=Thread(target=work)    
        t.start()