Python学习笔记- Python threading模块

Python threading模块

直接调用

# !/usr/bin/env python
# -*- coding:utf-8 -*-
import threading
import time

def sayhi(num):
    print("running on number:%s" % num)
    time.sleep(3)

if __name__ =='__main__':

    #生成两个线程实例
     t1 = threading.Thread(target=sayhi,args=(1,))
     t2 = threading .Thread(target = sayhi,args=(2,))

     #启动两个线程
     t1.start()
     t2.start()

    #打印线程名
     print(t1.getName())
     print(t2.getName())

继承调用

import threading
import time
class MyThread(threading.Thread):
    def __init__(self,num):
        # super(Mythread,self).__init__(self)
        threading.Thread.__init__(self)
        self.num = num

    def run(self):

        print('running on number%s' %self.num)
        time.sleep(3)

if __name__ == '__main__':

    t1 = MyThread(1)
    t2 = MyThread(2)
    t1.start()
    t2.start()

批量处理多线程及等待

import threading
import time

def sayhi(num):

        print('running on number%s' %num)
        time.sleep(5)

if __name__ == '__main__':
    '''
    t1 = MyThread(1)
    t2 = MyThread(2)
    t1.start()
    t2.start()
    '''
t_list=[] #用于存储实例
for i in range(100):
  t = threading.Thread(target=sayhi,args =[i,] ) #循环创建实例
  t.start()
  t_list.append(t) #将创建的实力添加到列表
for i in t_list:#循环列表中的创建的实例
    i.join() #在每个列表后面添加等待
print('##############main###############')

 

守护线程（Daemon） 

import threading
import time

def run(n):
    print('--------runnig----------')
    time.sleep(200)
    print('--------done------------')

def main(self):
    for i in range(5):
        t = threading.Thread(target=run,args=[i,])
        t.start()
        t.join()
        print('start thread',t.getName())
m = threading.Thread(target=main,args=[])
m.setDaemon(True)#将主线程设置为Daemon线程,它退出时,其它子线程会同时退出,不管是否执行完任务
m.start()
print('-----main thread done-----')

线程锁(互斥锁Mutex)

# !/usr/bin/env python
# -*- coding:utf-8 -*-
import threading
import time
def addNum():
    global num #在每个进程中都获得这个全局变量
    print('----get num:%s' %num)
    time.sleep(2)
    lock.acquire()#修改数据前加锁
    num-=1
    lock.release()#修改后释放锁

num = 100
thread_list=[]
lock = threading.Lock() #生成全局锁
for i in range(100):
    t=threading.Thread(target=addNum)
    t.start()
    thread_list.append(t)

for t in thread_list:
    t.join() #等待所有线程执行完毕

print('final Num:%s'%num)

递归锁(RLock)

# !/usr/bin/env python
# -*- coding:utf-8 -*-
import threading,time

def run1():
    print("grab the first part data")
    lock.acquire()
    global num
    num +=1
    lock.release()
    return num
def run2():
    print("grab the second part data")
    lock.acquire()
    global  num2
    num2+=1
    lock.release()
    return num2
def run3():
    lock.acquire()#加递归锁
    res = run1() #调用run1方法
    print('--------between run1 and run2-----')
    res2 = run2()#调用run2方法
    lock.release()#释放递归锁
    print(res,res2)


if __name__ == '__main__':

    num,num2 = 0,0 #初始化变量
    lock = threading.RLock()#创建线程锁
    for i in range(10):
        t = threading.Thread(target=run3) #创建线程
        t.start()

while threading.active_count() != 1:#判断是否只剩一个线程
    print(threading.active_count())
else:
    print('----all threads done---')
    print(num,num2)

Semaphore(信号量)

互斥锁 同时只允许一个线程更改数据，而Semaphore是同时允许一定数量的线程更改数据.

# !/usr/bin/env python
# -*- coding:utf-8 -*-

import threading,time

def run(n):
    semaphore.acquire()
    time.sleep(1)
    print("run the thread: %s
" %n)
    semaphore.release()

if __name__ == '__main__':

    num= 0
    semaphore  = threading.BoundedSemaphore(3) #最多允许5个线程同时运行
    for i in range(20):
        t = threading.Thread(target=run,args=(i,))
        t.start()

while threading.active_count() != 1:
    pass #print threading.active_count()
else:
    print('----all threads done---')
    print(num)

线程间同步和交互Event

An event is a simple synchronization object;

the event represents an internal flag, and threads
can wait for the flag to be set, or set or clear the flag themselves.

通过Event来实现两个或多个线程间的交互

Event = threading.Event() 

even.wait() 

event.set()

event.clear()

实例：

import threading,time
def light():
    if not event.isSet():
        event.set() #wait就不阻塞 #绿灯状态
    count = 0
    while True:
        if count < 10:
            print('33[42;1m--green light on---33[0m')
        elif count <13:
            print('33[43;1m--yellow light on---33[0m')
        elif count <20:
            if event.isSet():
                event.clear()
            print('33[41;1m--red light on---33[0m')
        else:
            count = 0
            event.set() #打开绿灯
        time.sleep(1)
        count +=1
def car(n):
    while 1:
        time.sleep(1)
        if  event.isSet(): #绿灯
            print("car [%s] is running.." % n)
        else:
            print("car [%s] is waiting for the red light.." %n)
            event.wait()
if __name__ == '__main__':
    event = threading.Event()
    Light = threading.Thread(target=light)
    Light.start()
    for i in range(3):
        t = threading.Thread(target=car,args=(i,))
        t.start()