Python中的多线程

Python3 线程中常用的两个模块为：

_thread

threading(推荐使用)

thread 模块已被废弃。用户可以使用 threading 模块代替。所以，在 Python3 中不能再使用"thread" 模块。为了兼容性，Python3 将 thread 重命名为 "_thread"。

函数时调用：

最简单的读线程案例：

#threading模块创建线程实例

#步骤：1.用Thread类创建一个实例 2.实例化后调用start方法启动线程

from threading import Thread

#线程函数

def threadDemo(msg):

    print(msg)

if __name__ == '__main__':

    #实例化线程类,target参数为线程执行的函数，args参数为线程函数的参数

    thread1 = Thread(target=threadDemo,args=('this is a thread demo',))

    thread1.start()

输出：this is a thread demo

继承式调用

#步骤：1.继承Thread类创建一个新的子类 2.实例化后调用start方法启动线程

#线程函数

def threadDemo(msg):

    print(msg)

class MyThread(Thread):

    def __init__(self,msg):

        super(MyThread,self).__init__()

        self.msg = msg

    def run(self):

        threadDemo(self.msg)

if __name__ == '__main__':

    t1 = MyThread('thread t1')

    t2 = MyThread('thread t2')

    t1.start()

    t2.start()

    t1.join()

    t2.join()

输出：thread t1

           thread t2

线程同步

线程在运行时是相互独立的，线程与线程间互不影响

def print_time(threadName,count,delay):

    while count:

        time.sleep(delay)

        print("%s: %s" % (threadName, time.ctime(time.time())))

        count -= 1

class MyThread(Thread):

    def __init__(self,name,count):

        super(MyThread,self).__init__()

        self.name = name

        self.count = count

    def run(self):

        print('线程开始'+self.name)

        print_time(self.name,self.count,2)

        print('线程结束'+self.name)

if __name__ == '__main__':

    th1 = MyThread('th1',5)

    th2 = MyThread('th2',5)

    th1.start()

    th2.start()

    th1.join()

    th2.join()

    print('--主线程结束--')

输出结果：

线程开始th1

线程开始th2

th1: Tue Dec 31 10:25:30 2019

th2: Tue Dec 31 10:25:30 2019

th1: Tue Dec 31 10:25:32 2019

th2: Tue Dec 31 10:25:32 2019

th1: Tue Dec 31 10:25:34 2019

th2: Tue Dec 31 10:25:34 2019

th1: Tue Dec 31 10:25:36 2019

th2: Tue Dec 31 10:25:36 2019

th1: Tue Dec 31 10:25:38 2019

线程结束th1

th2: Tue Dec 31 10:25:38 2019

线程结束th2

--主线程结束--