进程开启方式和进程在所有子进程结束之后才结束

1.主进程会等待所有子进程结束后才会程序结束

2.主线程也会等待所有子线程结束后才会主线程结束

3.from multiprocessing import Pool这个进程池,并不会等待所有的进程运行完成,而是主线程代码执行完成后程序就立即结束 所以这个进程池需要加p.close()和p.join()

4.from concurrent.futures import ThreadPoolExecutor,ProcessPoolExecutor 的进程池和线程池,主进程或者主线程会等进程池内或者线程 池内的任务运行完成,整 个程序才会结束

5.协程的问题,所有协程,主线程必须加join()阻塞,否则其他协程不运行.

6.关于守护进程的问题,守护进程是在主进程的代码结束后,立刻结束.守护线程是在所有子线程都结束后,守护线程结束.

示例一:

import threading
from time import ctime, sleep
import time

def ListenMusic(name):
        print ("Begin listening to %s. %s" %(name,ctime()))
        sleep(8)
        print("end listening to %s. %s" %(name,ctime()))

def RecordBlog(title):
        print ("Begin recording the %s! %s" %(title,ctime()))
        sleep(5)
        print('end recording the %s! %s' %(title,ctime()))

threads = []
t1 = threading.Thread(target=ListenMusic,args=('水手',))
t2 = threading.Thread(target=RecordBlog,args=('python线程',))
threads.append(t1)
threads.append(t2)

if __name__ == '__main__':
    for t in threads:
        # t.setDaemon(True) # 注意:一定在start之前设置,被主进程带走
        t.start()
        # t.join()  #
    # t1.join()
    # t1.setDaemon(True)

    # t2.join()########考虑这三种join位置下的结果？
    print ("all over %s" %ctime())

输出:

Begin listening to 水手. Sat Jun 11 12:43:11 2022
Begin recording the python线程! Sat Jun 11 12:43:11 2022
all over Sat Jun 11 12:43:11 2022
end recording the python线程! Sat Jun 11 12:43:16 2022
end listening to 水手. Sat Jun 11 12:43:19 2022

2,获取线程名,开启线程的方式一

import threading
import time

def sayhi(num):  # 定义每个线程要运行的函数
    print("running on number:%s" % num)
    time.sleep(3)

if __name__ == '__main__':
    t1 = threading.Thread(target = sayhi, args = (1,))  # 生成一个线程实例
    t2 = threading.Thread(target = sayhi, args = (2,))  # 生成另一个线程实例

    t1.start()  # 启动线程
    t2.start()  # 启动另一个线程

    print(t1.getName())  # 获取线程名
    print(t2.getName())

输出:

running on number:1
running on number:2
Thread-1
Thread-2

3,开启线程的方式二

import threading
import time


class MyThread(threading.Thread):
    def __init__(self, num):
        threading.Thread.__init__(self)
        self.num = num

    def run(self):  # 定义每个线程要运行的函数
        print("running on number:%s" % self.num)
        time.sleep(3)

if __name__ == '__main__':
    t1 = MyThread(1)
    t2 = MyThread(2)
    t1.start()
    t2.start()

    print("ending......")

输出:

running on number:1
running on number:2
ending......