# 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()
