Python3多进程 multiprocessing 模块实例详解

import multiprocessing
import os
def run_proc(name):
  print('Child process {0} {1} Running '.format(name, os.getpid()))
if __name__ == '__main__':
  print('Parent process {0} is Running'.format(os.getpid()))
  for i in range(5):
    p = multiprocessing.Process(target=run_proc, args=(str(i),))
    print('process start')
    p.start()
  p.join()
  print('Process close')

import multiprocessing
import os
import time
def run_task(name):
  print('Task {0} pid {1} is running, parent id is {2}'.format(name, os.getpid(), os.getppid()))
  time.sleep(1)
  print('Task {0} end.'.format(name))
if __name__ == '__main__':
  print('current process {0}'.format(os.getpid()))
  p = multiprocessing.Pool(processes=3)
  for i in range(6):
    p.apply_async(run_task, args=(i,))
  print('Waiting for all subprocesses done...')
  p.close()
  p.join()
  print('All processes done!')

import multiprocessing
import os
import time
def run_task(name):
  print('Task {0} pid {1} is running, parent id is {2}'.format(name, os.getpid(), os.getppid()))
  time.sleep(1)
  print('Task {0} end.'.format(name))
if __name__ == '__main__':
  print('current process {0}'.format(os.getpid()))
  p = multiprocessing.Pool(processes=3)
  for i in range(6):
    p.apply(run_task, args=(i,))
  print('Waiting for all subprocesses done...')
  p.close()
  p.join()
  print('All processes done!')

from multiprocessing import Process, Queue
import os, time, random
# 写数据进程执行的代码:
def proc_write(q,urls):
  print('Process(%s) is writing...' % os.getpid())
  for url in urls:
    q.put(url)
    print('Put %s to queue...' % url)
    time.sleep(random.random())
# 读数据进程执行的代码:
def proc_read(q):
  print('Process(%s) is reading...' % os.getpid())
  while True:
    url = q.get(True)
    print('Get %s from queue.' % url)
if __name__=='__main__':
  # 父进程创建Queue，并传给各个子进程：
  q = Queue()
  proc_writer1 = Process(target=proc_write, args=(q,['url_1', 'url_2', 'url_3']))
  proc_writer2 = Process(target=proc_write, args=(q,['url_4','url_5','url_6']))
  proc_reader = Process(target=proc_read, args=(q,))
  # 启动子进程proc_writer，写入:
  proc_writer1.start()
  proc_writer2.start()
  # 启动子进程proc_reader，读取:
  proc_reader.start()
  # 等待proc_writer结束:
  proc_writer1.join()
  proc_writer2.join()
  # proc_reader进程里是死循环，无法等待其结束，只能强行终止:
  proc_reader.terminate()

from multiprocessing import Process, Pipe
def send(pipe):
  pipe.send(['spam'] + [42, 'egg'])  # send 传输一个列表
  pipe.close()
if __name__ == '__main__':
  (con1, con2) = Pipe()              # 创建两个 Pipe 实例
  sender = Process(target=send, args=(con1, ))   # 函数的参数，args 一定是实例化之后的 Pip 变量，不能直接写 args=(Pip(),)
  sender.start()                  # Process 类启动进程
  print("con2 got: %s" % con2.recv())       # 管道的另一端 con2 从send收到消息
  con2.close()                   # 关闭管道

from multiprocessing import Process, Pipe
def talk(pipe):
  pipe.send(dict(name='Bob', spam=42))      # 传输一个字典
  reply = pipe.recv()               # 接收传输的数据
  print('talker got:', reply)
if __name__ == '__main__':
  (parentEnd, childEnd) = Pipe()         # 创建两个 Pipe() 实例，也可以改成 conf1， conf2
  child = Process(target=talk, args=(childEnd,)) # 创建一个 Process 进程，名称为 child
  child.start()                  # 启动进程
  print('parent got:', parentEnd.recv())     # parentEnd 是一个 Pip() 管道，可以接收 child Process 进程传输的数据
  parentEnd.send({x * 2 for x in 'spam'})     # parentEnd 是一个 Pip() 管道，可以使用 send 方法来传输数据
  child.join()                  # 传输的数据被 talk 函数内的 pip 管道接收，并赋值给 reply
  print('parent exit')