【Rollo的Python之路】多线程实例 Join 与Daemon

1.0 threading 的join方法就是用来阻塞用的，可以阻塞主线程，等待所的子线程结束后，然后再运行后面的程序：

import threading
import time
from time import ctime,sleep

def music(func):
    for i in range(2):
        print("I was listening to %s.%s" %(func,ctime()))
        sleep(1)
        print("end listening %s" % ctime())

def movie(func):
    for i in range(2):
        print("I was at the %s %s" %(func,ctime()))
        sleep(5)
        print("end watch %s" % ctime())

threads = []

t1 = threading.Thread(target=music,args=("overstock",))
threads.append(t1)
t2 = threading.Thread(target=movie,args=("kill them all",))
threads.append(t2)

if __name__ =="__main__":
    for t in threads:
        t.start()

    t2.join()
    print("all over %s" %ctime())

此时，会等t2运行完成后，才执行最后的print语句。

import threading
import time
from time import ctime,sleep

def music(func):
    for i in range(2):
        print("I was listening to %s.%s" %(func,ctime()))
        sleep(1)
        print("end listening %s" % ctime())

def movie(func):
    for i in range(2):
        print("I was at the %s %s" %(func,ctime()))
        sleep(5)
        print("end watch %s" % ctime())

threads = []

t1 = threading.Thread(target=music,args=("overstock",))
threads.append(t1)
t2 = threading.Thread(target=movie,args=("kill them all",))
threads.append(t2)

if __name__ =="__main__":
    for t in threads:
        t.start()

    t1.join()
    print("all over %s" %ctime())

此时，只会运行完t1后，就会执行最后的print

2.0 threading 的daemon，当我们使用setDaemon(True)方法，设置子线程为守护线程时，主线程一旦执行结束，则全部线程全部被终止执行，可能出现的情况就是，子线程的任务还没有完全执行结束，就被迫停止

import threading
import time
from time import ctime,sleep

def music(func):
    for i in range(2):
        print("I was listening to %s.%s" %(func,ctime()))
        sleep(1)
        print("end listening %s" % ctime())

def movie(func):
    for i in range(2):
        print("I was at the %s %s" %(func,ctime()))
        sleep(5)
        print("end watch %s" % ctime())

threads = []

t1 = threading.Thread(target=music,args=("overstock",))
threads.append(t1)
t2 = threading.Thread(target=movie,args=("kill them all",))
threads.append(t2)

if __name__ =="__main__":
    for t in threads:
        t.setDaemon(True)
        t.start()

    print("all over %s" %ctime())

跑完主线程，直接关闭程序。

import threading
import time
from time import ctime,sleep

def music(func):
    for i in range(2):
        print("I was listening to %s.%s" %(func,ctime()))
        sleep(1)
        print("end listening %s" % ctime())

def movie(func):
    for i in range(2):
        print("I was at the %s %s" %(func,ctime()))
        sleep(5)
        print("end watch %s" % ctime())

threads = []

t1 = threading.Thread(target=music,args=("overstock",))
threads.append(t1)
t2 = threading.Thread(target=movie,args=("kill them all",))
threads.append(t2)

if __name__ =="__main__":
    t2.setDaemon(True)
    for t in threads:
        
        t.start()

    print("all over %s" %ctime())

t2 setDaemon(True),守护线程，t1还是得等，但是只要t1运行完，就会不等t2，直接关闭程序

3.0 threading.current_thread()  线程名

4.0 threading.active_count() 在运行的线程数量。