import osimport timeret = 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 osimport timeret = os.fork()if ret ==0:    print('......1......')else:    print('......2......')ret = os.fork()if ret ==0:    print('......11......')else:    print('......22.....')

import osimport timeret = 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,Managerimport osdef 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