Question

我希望有一个线程在后台等待UDP数据包，而在没有收到数据包时我希望脚本能够做另外的事情。但是当我启动线程时，脚本会等待UDP数据包并停止。

import threading
import socket


def rec_UDP():
    while True:
        # UDP commands for listening
        UDP_PORT = 5005
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        sock.bind(('10.0.0.15', UDP_PORT))
        data, addr = sock.recvfrom(1024)
        print "received message:", data
        return data


# The thread that ables the listen for UDP packets is loaded
listen_UDP = threading.Thread(target=rec_UDP())
listen_UDP.start()

data = 'Nothing received'

while True:
    print 'The packet received is: ' + data

Answer 1

通过在函数之后附加()，代码调用直接阻塞主线程的函数，而不是在分离的线程中运行函数。

删除函数名后的()。

listen_UDP = threading.Thread(target=rec_UDP)

Answer 2

这不适用于 Python 3，但它让我走上了正确的道路。这是我的 Python 3 版本。

#!/usr/bin/python3

import _thread, time, socket

data = ''   # Declare an empty variable
# UDP setup for listening
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('', 12345))  # I'm using port 12345 to bind to

# Define a function for the thread
def listening_thread():
    global data     # data needs to be defined as global inside the thread
    while True:
        data_raw, addr = sock.recvfrom(1024)
        data = data_raw.decode()    # My test message is encoded
        print ("Received message inside thread:", data)

try:
   _thread.start_new_thread(listening_thread, ())
except:
    print ("Error: unable to start thread")
    quit()


while 1:
    print ('Now I can do something useful while waiting in the main body.')
    if data:
        print ('THE PACKET RECEIVED BY THE MAIN BODY IS: ' + data)
        data = ''   # Empty the variable ready for the next one
    time.sleep(2)

在后台接收UDP数据包（PYTHON）

2 个答案: