python-线程互斥锁与递归锁
1.线程跟进程里的互斥锁一样:
将多个并发任务的部分代码（只涉及修改共享数据的代码，编程串行线程或进程操作）
加锁可以保证多个进程修改同一数据，同一时间只能只要一个任务可以进行修改，这样可以保证数据的安全性，单牺牲了速度
from threading import thread,lock
import time
mutex=lock()
x=100
def task():
global x
mutex.acquire()
temp=x
time.sleep(1)
x=temp-1
mutex.release()
if __name__ =='__main__':
t_l=[]
start=time.time()
for i in tange():
t=thread(target=task)
t_l.append(t)
t.start()
for t in t_l:
t.join()
shop=time.time()
print(x,stop-start)
递归锁：互斥锁一旦运用在多个修改共享数据的时候，会出现锁死的情况，所以这个时候需要用到递归锁
特点：可以连续的acquire()
from threading import Thread,Lock,active_count,RLock
import time
# mutexA=Lock()
# mutexB=Lock()
obj=RLock() #递归锁的特点：可以连续的acquire
mutexA=obj
mutexB=obj
class Mythread(Thread):
def run(self):
self.f1()
self.f2()
def f1(self):
mutexA.acquire()
print('%s 拿到A锁' %self.name)
mutexB.acquire()
print('%s 拿到B锁' %self.name)
mutexB.release()
mutexA.release()
def f2(self):
mutexB.acquire()
print('%s 拿到B锁' %self.name)
time.sleep(1)
mutexA.acquire()
print('%s 拿到A锁' %self.name)
mutexA.release()
mutexB.release()
if __name__ == '__main__':
for i in range(10):
t=Mythread()
t.start()
print(active_count()) #统计当前线程数#递归锁的特点：可以连续的acquire
mutexA=obj
mutexB=obj
class Mythread(Thread):
def run(self):
self.f1()
self.f2()
def f1(self):
mutexA.acquire()
print('%s 拿到A锁' %self.name)
mutexB.acquire()
print('%s 拿到B锁' %self.name)
mutexB.release()
mutexA.release()
def f2(self):
mutexB.acquire()
print('%s 拿到B锁' %self.name)
time.sleep(1)
mutexA.acquire()
print('%s 拿到A锁' %self.name)
mutexA.release()
mutexB.release()
if __name__ == '__main__':
for i in range(10):
t=Mythread()
t.start()
print(active_count()) #统计当前线程数