python使用多进程的实例详解

import os
from multiprocessing import Process
# 子进程要执行的代码
def task(name):
  print('run child process %s (%s)...' % (name, os.getpid()))
if __name__ == '__main__':
  print('parent process %s.' % os.getpid())
  p = Process(target=task, args=('test',))
  p.start()
  p.join()
  print('process end.') 

import multiprocessing
import os
from multiprocessing import current_process
class Worker(multiprocessing.Process):
  def run(self):
    name = current_process().name # 获取当前进程的名称
    print('run child process <%s> (%s)' % (name, os.getpid()))
    print('In %s' % self.name)
    return
if __name__ == '__main__':
  print('parent process %s.' % os.getpid())
  p = Worker()
  p.start()
  p.join()
  print('process end.') 
　　* 停止进程

import multiprocessing
import time
def worker():
  print('starting worker')
  time.sleep(0.1)
  print('finished worker')
if __name__ == '__main__':
  p = multiprocessing.Process(target=worker)
  print('执行前:', p.is_alive())
  p.start()
  print('执行中:', p.is_alive())
  p.terminate() # 发送停止号
  print('停止:', p.is_alive())
  p.join()
  print('等待完成:', p.is_alive()) 

import multiprocessing
def worker(num):
  print(f'Worker:%s %s', num)
  return
if __name__ == '__main__':
  jobs = []
  for i in range(5):
    p = multiprocessing.Process(target=worker, args=(i,))
    jobs.append(p)
    p.start() 

import os
import random
import time
from multiprocessing import Pool
from time import ctime
def task(name):
  print('start task %s (%s)...' % (name, os.getpid()))
  start = time.time()
  time.sleep(random.random() * 3)
  print('end task %s runs %0.2f seconds.' % (name, (time.time() - start)))
if __name__ == '__main__':
  print('parent process %s.' % os.getpid())
  p = Pool() # 初始化进程池
  for i in range(5):
    p.apply_async(task, args=(i,)) # 追加任务 apply_async 是异步非阻塞的，就是不用等待当前进程执行完毕，随时根据系统调度来进行进程切换。
  p.close()
  p.join() # 等待所有结果执行完毕，会等待所有子进程执行完毕，调用join()之前必须先调用close()
  print(f'all done at: {ctime()}') 

import os
import random
import time
from multiprocessing import Pool, current_process
from time import ctime
def task(name):
  print('start task %s (%s)...' % (name, os.getpid()))
  start = time.time()
  time.sleep(random.random() * 3)
  print('end task %s runs %0.2f seconds.' % (name, (time.time() - start)))
  return current_process().name + 'done'
if __name__ == '__main__':
  print('parent process %s.' % os.getpid())
  result = []
  p = Pool() # 初始化进程池
  for i in range(5):
    result.append(p.apply_async(task, args=(i,))) # 追加任务 apply_async 是异步非阻塞的，就是不用等待当前进程执行完毕，随时根据系统调度来进行进程切换。
  p.close()
  p.join() # 等待所有结果执行完毕
  for res in result:
    print(res.get()) # get()函数得出每个返回结果的值
  print(f'all done at: {ctime()}')