python 多线程

多线程流程

1. 导入模块

   import threading

2. 通过线程类型创建线程对象

   线程对象 = threading.Thread(target = '待执行函数',name = (线程命名))

3. 启动线程执行任务

   线程对象.start()

启动线程

创建子线程

sing_thread = threading.Thread(target = sing)
dance_thread = threading.Thread(target = dance)

启动子线程

sing_thread.start()
dance_thread.start()

线程传参

• args 以元组方式传递

# target 线程函数名
# args 以元组的方式传递参数  args只有一个参数的时候，一定在后面加上',' ！！！
sing_thread = threading.Thread(target = sing,args = (3,))
sing_thread.start()

• kwargs 以字典方式传递

# target 线程函数名
# kwargs 以字典的方式传递参数
dance_thread = threading.Thread(target = dance,kwargs = {'count': 3})
dance_thread.start()

例：

import threading,time

def sing(num):
    for i in range(num):
        print('sing')
        time.sleep(1)
def dance(num):
    for i in range(num):
        print('dance')
        time.sleep(1)
if __name__ == '__main__':
    sing_thread = threading.Thread(target= sing ,args= (3,))
    dance_thread = threading.Thread(target = dance,kwargs= {'num': 5})

    sing_thread.start()
    dance_thread.start()

主线程和子线程的结束顺序

• 默认主线程等待子线程结束

设置主线程结束子线程销毁

• thread 添加 daemon = True
• 或者在启动线程前添加sing_thread.setDaemon(Ture)

sing_thread.Thread(target = sing ,daemon = Ture)

线程之间的执行顺序

• 默认无序

证实线程之间是无序的

# 通过current_thread方法获取线程对象
current_thread = threading.current_thread()
# 通过current_thread对象可以知道相关信息，例如被创建的顺序
print('current_thread')

import threading,time

def sing():
        time.sleep(2)
        print(threading.current_thread())

if __name__ == '__main__':
    for i in range(5):
        sing_thread = threading.Thread(target=sing)
        sing_thread.start()