Python多进程-蒲公英云

安装：

pip install multiprocess

使用：

import multiprocessing

创建进程：

multiprocessing.Process([group [, target [, name [, args [, kwargs]]]]])
# target表示调用对象
# args表示调用对象的位置参数元组
# kwargs表示调用对象的字典
# name为别名
# group实质上不使用

方法:
is_alive() ：进程是否存活
join([timeout])
run()
start() ：启动一个进程
terminate()

属性：authkey、daemon(要通过start()设置),exitcode(进程在运行时为None、如果为–N，表示被信号N结束）、name、pid。其中daemon是父进程终止后自动终止，且自己不能产生新进程，必须在start()之前设置。

创建一个单进程：

import multiprocessing
import time
def func():
    for i in range(5):
        print(i,"*"*10)
        time.sleep(2)
if __name__ == '__main__':
    p=multiprocessing.Process(target=func)
    p.start()
    print("p.pid:",p.pid)
    print("p.name",p.name)
    print("p.is_alive",p.is_alive())
# p.pid: 11792
# p.name Process-1
# p.is_alive True
# 0 **********
# 1 **********
# 2 **********
# 3 **********
# 4 **********

2.创建函数并将其作为多进程

import multiprocessing
import time
def func1():
    for i in range(5):
        print(i,"*"*10)
        time.sleep(2)
def func2():
    for i in range(5):
        print(i*10,"*"*10)
        time.sleep(2)
if __name__ == '__main__':
    p1=multiprocessing.Process(target=func1)
    p1.start()
    p2 = multiprocessing.Process(target=func2)
    p2.start()
    print("The number of CPU is:" + str(multiprocessing.cpu_count()))
# The number of CPU is:2
# 0 **********
# 0 **********
# 1 **********
# 10 **********
# 2 **********
# 20 **********
# 3 **********
# 30 **********
# 4 **********
# 40 **********

将进程定义为类

import multiprocessing
import time
class Mytest(multiprocessing.Process):
    def __init__(self,interval):
        multiprocessing.Process.__init__(self)
        self.interval=interval
    def run(self):
        n = 5
        while n > 0:
            print("the time is {0}".format(time.ctime()))
            time.sleep(self.interval)
            n -= 1
if __name__ == '__main__':
    p=Mytest(2)
    p.start()
# the time is Tue Apr 27 20:31:10 2021
# the time is Tue Apr 27 20:31:12 2021
# the time is Tue Apr 27 20:31:14 2021
# the time is Tue Apr 27 20:31:16 2021
# the time is Tue Apr 27 20:31:18 2021

设置daemon属性，主进程结束，子进程就随着结束

不加daemon:

import multiprocessing
import time
def func(sle):
    print("time now_1:{}".format(time.ctime()))
    time.sleep(sle)
    print("time now_2:{}".format(time.ctime()))
if __name__ == '__main__':
    p=multiprocessing.Process(target=func,args=(2,))
    p.start()
    print("end!")
# end!
# time now_1:Tue May 18 16:52:22 2021
# time now_2:Tue May 18 16:52:24 2021

加上daemon:

import multiprocessing
import time
def func(sle):
    print("time now_1:{}".format(time.ctime()))
    time.sleep(sle)
    print("time now_2:{}".format(time.ctime()))
if __name__ == '__main__':
    p=multiprocessing.Process(target=func,args=(2,))
    p.daemon=True
    p.start()
    print("end!")
# end!

join让其中一个子进程运行，在这个子进程运行完毕，在让另外一个子进程运行，所以在其中一个子进程运行期间，其他进程只能按着固有的顺序等待。

import multiprocessing
import time
def funcA():
    sle=2
    print("funcA_time now_1:{}".format(time.ctime()))
    time.sleep(sle)
    print("funcA_time now_2:{}".format(time.ctime()))
    return sle
def funcB():
    t=funcA()
    print("funcB_time now_1:{}".format(time.ctime()))
    time.sleep(t)
    print("funcB_time now_2:{}".format(time.ctime()))
if __name__ == '__main__':
    p1=multiprocessing.Process(target=funcA)
    p2=multiprocessing.Process(target=funcB)
    p1.start()
    p1.join()
    p2.start()
    p2.join()
    print("end!")
# 
# funcA_time now_1:Tue May 18 17:12:28 2021
# funcA_time now_2:Tue May 18 17:12:30 2021
# funcA_time now_1:Tue May 18 17:12:30 2021
# funcA_time now_2:Tue May 18 17:12:32 2021
# funcB_time now_1:Tue May 18 17:12:32 2021
# funcB_time now_2:Tue May 18 17:12:34 2021
# end!

互斥锁
加锁可以保证多个进程修改同一块数据时，同一时间只能有一个任务可以进行修改，即串行的修改

from multiprocessing import Lock,Process
import time
import os
def funcA(mutex):
    sle=2
    print("funcA_time now_1:{} pid:{}".format(time.ctime(),os.getpid()))
    time.sleep(sle)
    print("funcA_time now_2:{} pid:{}".format(time.ctime(),os.getpid()))
    return sle
def funcB(mutex):
    t=funcA(mutex)
    print("funcB_time now_1:{}".format(time.ctime()))
    time.sleep(t)
    print("funcB_time now_2:{}".format(time.ctime()))
if __name__ == '__main__':
    mutex=Lock()
    p1=Process(target=funcA,args=(mutex,))
    p2=Process(target=funcA,args=(mutex,))
    p1.start()
    print(p1.pid)
    time.sleep(10)
    p2.start()
    print(p2.pid)
    print("end!")
# 7292
# funcA_time now_1:Tue May 18 17:23:48 2021 pid:7292
# funcA_time now_2:Tue May 18 17:23:50 2021 pid:7292
# 20396
# end!
# funcA_time now_1:Tue May 18 17:23:58 2021 pid:20396
# funcA_time now_2:Tue May 18 17:24:00 2021 pid:20396