如何在python中多次运行线程 [英] How to run a thread more than once in python

问题描述

我试图多次运行一个线程并不断出现错误:

I am trying to run a thread more than once and keep getting an error:

RuntimeError: threads can only be started once

我尝试读取多线程并在我的代码中实现它，但是没有任何运气.

I have tried reading up multithreading and implementing it in my code without any luck.

这是我正在执行的函数:

Here is the function I am threading:

def receive(q):
    host = ""
    port = 13000
    buf = 1024
    addr = (host,port)
    Sock = socket(AF_INET, SOCK_DGRAM)
    Sock.bind(addr)
    (data, addr) = Sock.recvfrom(buf)
    q.put(data)

这是我要运行的代码:

q = Queue.Queue()
r = threading.Thread(target=receive, args=(q,))

while True:
    r.start()
    if q.get() == "stop":
        print "Stopped"
        break
    print "Running program"

当发送stop消息时，该程序应退出while循环，但由于多线程而无法运行. while循环应不断打印出Running program，直到发送stop消息为止.

When the stop message gets sent, the program should break out of the while loop, but it does not run due to multithreading. The while loop should constantly print out Running program, until the stop message is sent.

队列用于从receive函数(即stop)接收变量data.

The queue is used to receive the variable data from the receive function (which is the stop).

推荐答案

这是一个有效的示例(适用于python 2.7).

Here is a working example (for python 2.7).

程序有两种操作模式:

• 不带任何参数，它将运行接收循环
• 带有参数的它发送一个数据报

请注意在client的while循环之外如何调用r.start()和r.terminate(). 另外，receive具有while True循环.

Note how r.start() and r.terminate() are called outside of the while loop in client. Also, receive has a while True loop.

import sys
import socket
from multiprocessing import Process, Queue

UDP_ADDR = ("", 13000)

def send(m):
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) 
    sock.sendto(m, UDP_ADDR)

def receive(q):
    buf = 1024
    Sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    Sock.bind(UDP_ADDR)
    while True:
      (data, addr) = Sock.recvfrom(buf)
      q.put(data)

def client():
  q = Queue()
  r = Process(target = receive, args=(q,))
  r.start()

  print "client loop started"
  while True:
      m = q.get()
      print "got:", m
      if m == "stop":
          break
  print "loop ended"

  r.terminate()

if __name__ == '__main__':
  args = sys.argv
  if len(args) > 1:
    send(args[1])
  else:
    client()

这篇关于如何在python中多次运行线程的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！