pyhton多线程

多线程的两种实现方式

方法1：直接使用threading.Thread()

import threading

def run(n):
    print("current task：", n)

if __name__ == "__main__":
    t1 = threading.Thread(target=run, args=("thread 1",))
    t2 = threading.Thread(target=run, args=("thread 2",))
    t1.start()
    t2.start()

方法2：继承threading.Thread来自定义线程类，重写run方法

import threading

class MyThread(threading.Thread):
    def __init__(self, n):
        super(MyThread, self).__init__()  # 重构run函数必须要写
        self.n = n
    def run(self):
        print("current task：", n)

if __name__ == "__main__":
    t1 = MyThread("thread 1")
    t2 = MyThread("thread 2")

    t1.start()
    t2.start()

join和守护进程实例

1，多线程的默认情况

默认情况下，主线程运行完自己结束，线程继续运行直到结束

import threading, time
def doWaiting1():
    print('start waiting1: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(3)
    print("线程1奉命报道")
    print('stop waiting1: ' + time.strftime('%H:%M:%S') + "\n")
def doWaiting2():
    print('start waiting2: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(8)
    print("线程2奉命报道")
    print('stop waiting2: ', time.strftime('%H:%M:%S') + "\n")

tsk = []

# 创建并开启线程1
thread1 = threading.Thread(target = doWaiting1)
thread1.start()
tsk.append(thread1)

# 创建并开启线程2
thread2 = threading.Thread(target = doWaiting2)
thread2.start()
tsk.append(thread2)

# 计时程序
print('start join: ' + time.strftime('%H:%M:%S')  )
print('end join: ' + time.strftime('%H:%M:%S') )

输出结果

start waiting1: 20:03:30
start waiting2: 20:03:30

start join: 20:03:30
end join: 20:03:30

线程1奉命报道
stop waiting1: 20:03:33

线程2奉命报道
stop waiting2:  20:03:38

2，开启守护线程

主进程结束，线程立马结束

import threading, time
def doWaiting1():
    print('start waiting1: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(3)
    print("线程1奉命报道")
    print('stop waiting1: ' + time.strftime('%H:%M:%S') + "\n")
def doWaiting2():
    print('start waiting2: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(8)
    print("线程2奉命报道")
    print('stop waiting2: ', time.strftime('%H:%M:%S') + "\n")

tsk = []

# 创建并开启线程1
thread1 = threading.Thread(target = doWaiting1)
thread1.setDaemon(True)
thread1.start()
tsk.append(thread1)

# 创建并开启线程2
thread2 = threading.Thread(target = doWaiting2)
thread2.setDaemon(True)
thread2.start()
tsk.append(thread2)

print('start join: ' + time.strftime('%H:%M:%S')  )
print('end join: ' + time.strftime('%H:%M:%S') )

运行结果

start waiting1: 20:10:04
start waiting2: 20:10:04

start join: 20:10:04
end join: 20:10:04

3，加入join后

主进程一直等到线程结束后才结束

import threading, time
def doWaiting1():
    print('start waiting1: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(3)
    print("线程1奉命报道")
    print('stop waiting1: ' + time.strftime('%H:%M:%S') + "\n")
def doWaiting2():
    print('start waiting2: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(8)
    print("线程2奉命报道")
    print('stop waiting2: ', time.strftime('%H:%M:%S') + "\n")

tsk = []

# 创建并开启线程1
thread1 = threading.Thread(target = doWaiting1)
thread1.start()
tsk.append(thread1)

# 创建并开启线程2
thread2 = threading.Thread(target = doWaiting2)
thread2.start()
tsk.append(thread2)

print('start join: ' + time.strftime('%H:%M:%S')  )
for t in tsk:
    print('%s线程到了'%t)
    t.join()
print('end join: ' + time.strftime('%H:%M:%S') )

运行结果

start waiting1: 20:14:35
start waiting2: 20:14:35

start join: 20:14:35

<Thread(Thread-1, started 19648)>线程到了
线程1奉命报道
stop waiting1: 20:14:38

<Thread(Thread-2, started 24056)>线程到了
线程2奉命报道
stop waiting2:  20:14:43

end join: 20:14:43

4,不设置守护进程但join设置超时

超时时间到了，主线程不再等待，自己结束
每一个线程都可能会提供主线程的等待时间，主线程的等待时间≤“线程数*timeout”

import threading, time
def doWaiting1():
    print('start waiting1: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(2)
    print("线程1奉命报道")
    print('stop waiting1: ' + time.strftime('%H:%M:%S') + "\n")
def doWaiting2():
    print('start waiting2: ' + time.strftime('%H:%M:%S') + "\n")
    time.sleep(8)
    print("线程2奉命报道")
    print('stop waiting2: ', time.strftime('%H:%M:%S') + "\n")

tsk = []

# 创建并开启线程1
thread1 = threading.Thread(target = doWaiting1)
thread1.start()
tsk.append(thread1)

# 创建并开启线程2
thread2 = threading.Thread(target = doWaiting2)
thread2.start()
tsk.append(thread2)

print('start join: ' + time.strftime('%H:%M:%S')  )
for t in tsk:
    print("开始:"+time.strftime('%H:%M:%S'))
    print('%s线程到了'%t)
    t.join(5)
    print("结束:" + time.strftime('%H:%M:%S'))
print('end join: ' + time.strftime('%H:%M:%S') )

运行结果

start waiting1: 21:14:25
start waiting2: 21:14:25

start join: 21:14:25

开始:21:14:25
<Thread(Thread-1, started 22348)>线程到了
线程1奉命报道
stop waiting1: 21:14:27
结束:21:14:27

开始:21:14:27
<Thread(Thread-2, started 13164)>线程到了
结束:21:14:32

end join: 21:14:32

线程2奉命报道
stop waiting2:  21:14:33

5，开启守护线程并且设置等待时间

线程和主线程都会在守护时间到了之后结束