python 进程复习

import os
import time
ret = os.fork() # 创建子线程

if ret ==0: # 子进程中返回值为0，父进程>0
    while True:
        print('......1......')
        time.sleep(1)

else:
    while True:
        print('......2......')
        time.sleep(1)

 多fork问题，以下代码会出现4个进程

import os
import time
ret = os.fork()

if ret ==0:
    print('......1......')

else:
    print('......2......')


ret = os.fork()

if ret ==0:
    print('......11......')

else:
    print('......22.....')

import os
import time
ret = os.fork()

if ret ==0:
    print('......1......')

else:
    print('......2......')


    ret = os.fork()

    if ret ==0:
        print('......11......')

    else:
        print('......22.....')

 进程间通信

进程之间默认无关联

普通进程间通信用 Queue队列

进程池中用Manager().Queue()

q.qsize()

q.full()

q.empty()

q.put()

q.get()

q.put_nowait()

q.get_nowait()

多进程文件拷贝案例

from multiprocessing import Pool,Manager
import os

def copyFileName(name,oldFolderName,newFolderName,queue):
    '完成copy一个文件的功能'
    fr = open(oldFolderName + '/' + name)
    fw = open(newFolderName + '/' + name,'w')

    content = fr.read()
    fw.write(content)

    fr.close()
    fw.close()
    
    queue.put(name)

def main():
    
    # 0,获取永远要copy的文件夹名字
    oldFolderName = input('请输入文件夹的名字：')

    # 1.创建一个文件夹
    newFolderName = oldFolderName + '-复件'
    os.mkdir(newFolderName)

    # 2.获取old文件夹中所有文件的名字
    fileNames = os.listdir(oldFolderName)

    # 3.使用多进程的方式copy原文件夹中所有文件到新的文件夹中
    pool = Pool(5)
    
    #创建队列，计数
    queue = Manager().Queue()

    for name in fileNames:
        pool.apply_async(copyFileName,args=(name,oldFolderName,newFolderName,queue))
    
    num = 0
    allNum = len(fileNames)
    while num<allNum:
        queue.get()
        num += 1
        copyRate = num/allNum
        print('
copy的进度是：%.2f%%'%(copyRate*100),end='')
        
    print('
已完成拷贝。。。。。')
    
if __name__ == '__main__':
    main()