113-python-多线程( 锁 )

# 互斥锁

"""
    # 牺牲效率保证数据安全
    # 出现两把或两把以上的锁,会出现 死锁
"""

from threading import Thread,Lock

def fn(lock):
    global n
    lock.acquire()
    num = n
    n = num - 1
    lock.release()
n = 10

l = Lock()
lis = []
for i in range(10):
    t = Thread(target=fn,args=(l,))
    lis.append(t)
    t.start()

for i in lis:
    i.join()

print(n)

　　

# 递归锁
"""
    # 在同一个线程中拿多少把钥匙都可以
    # 但是在不同的线程中,只能有一个线程拿到钥匙
"""

from threading import RLock
fork_lock = noodle_lock = RLock()

def eat1(name):
    noodle_lock.acquire()
    print('%s拿到1'%name)
    fork_lock.acquire()
    print('%s拿到1+'%name)
    print('%s: 1+1'%name)
    fork_lock.release()
    noodle_lock.release()

def eat2(name):
    fork_lock.acquire()
    print('%s拿到2'%name)
    noodle_lock.acquire()
    print('%s拿到2+'%name)
    print('%s2+2'%name)
    noodle_lock.release()
    fork_lock.release()

Thread(target=eat1,args=('q',)).start()
Thread(target=eat1,args=('w',)).start()
Thread(target=eat2,args=('e',)).start()
Thread(target=eat2,args=('r',)).start()