python多线程及互斥锁使用
def RunThread(target, *args): #传入一个函数多线程执行
print u"启动线程:", target.__name__
t = threading.Thread(target = target, args = args)
#t.setDaemon(True) #设置为守护线程 当主进程结束后所有子线程都会结束
t.start()
def fun1(): #每3秒输出一次fun1 总共输出5次
for i in range(5):
print "fun1"
time.sleep(3)
def fun2(count, sleep): #每sleep输出一次fun2 总共输出count次
for i in range(count):
print "fun2"
time.sleep(sleep)
RunThread(fun1) #创建一个线程运行fun1函数
RunThread(fun2, 5, 1) #创建一个线程运行fun2函数并给fun2函数传参5和1
print "end!"
'''
输出
启动线程: fun1
fun1启动线程:
fun2
fun2end!
fun2
fun2
fun1
fun2
fun2
fun1
fun1
fun1
'''
使用threading模块创建多线程
x = 0
def fun1():
global x
for i in range(1000):
x = x + 1
def fun2():
global x
for i in range(1000):
x = x + 1
t = threading.Thread(target = fun1)
t.start()
t = threading.Thread(target = fun2)
t.start()
time.sleep(3) #3秒足够让两个线程运行完毕
print x
#输出1603 和预计不符
多线程修改同一个全局变量出现问题
lock = threading.Lock()
x = 0
def fun1():
global lock, x
for i in range(1000):
lock.acquire() #加锁
x = x + 1
lock.release() #解锁
def fun2():
global lock, x
for i in range(1000):
lock.acquire()
x = x + 1
lock.release()
t = threading.Thread(target = fun1)
t.start()
t = threading.Thread(target = fun2)
t.start()
time.sleep(3) #3秒足够让两个线程运行完毕
print x
#使用互斥锁 输出正确结果2000
使用互斥锁保证数据正确
lock = threading.Lock()
def RunThread(target, *args): #传入一个函数多线程执行
print u"启动线程:", target.__name__
t = threading.Thread(target = target, args = args)
#t.setDaemon(True) #设置为守护线程 当主进程结束后所有子线程都会结束
t.start()
def fun():
global lock
lock.acquire()
print "lock"
time.sleep(2)
lock.release()
print "unlock"
RunThread(fun)
RunThread(fun)
for i in range(5):
time.sleep(1)
print "" #输出换行
'''
输出
启动线程: fun
启动线程:lock
fun
nlocklock
nlock
'''
当线程使用acquire尝试锁定lock时发现已经被锁定则进入阻塞状态 等待lock的解锁再继续运行
lock = threading.Lock()
x = 0
def fun1():
global lock, x
for i in range(1000):
with lock: #执行with下指令自动加锁执行完毕自动解锁
x = x + 1
def fun2():
global lock, x
for i in range(1000):
with lock:
x = x + 1
t = threading.Thread(target = fun1)
t.start()
t = threading.Thread(target = fun2)
t.start()
time.sleep(3) #3秒足够让两个线程运行完毕
print x
with 更加方便的加锁解锁