你的UDP收发程序之所以只能收到第一条数据，核心是两个关键问题导致的：

1. 发送端被recvfrom阻塞，后续发送无法执行 #

在SendSocket函数里，你发送数据后调用了UDPSocket.recvfrom(bufferSize)，但接收端完全没有发送回复的逻辑。这就导致发送端在第一次发送后，会一直卡在recvfrom步骤等待回复，后面两次循环的SendSocket调用根本没机会执行。

2. 接收端没有持续监听，仅执行一次接收 #

接收端只定义了ReceiveSocket函数，但没有循环调用它，所以程序只会执行一次接收操作，拿到第一条数据后就停止运行了，不会继续监听后续的UDP数据包。

修改后的代码 #

发送端（send文件） #

如果你的业务不需要接收回复，直接移除阻塞的recvfrom相关代码即可：

import socket
import pickle

# 请替换为你实际使用的端口值
LocalReadPort = 1234
EnginePort = 5678

UDPSocket = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM)
bufferSize = 1024

def SendSocket(Packet, Port):
    global UDPSocket
    global bufferSize
    print('Sending data...')
    AddressPort = ("127.0.0.2", Port)
    UDPSocket.sendto(Packet, AddressPort)
    # 移除不需要的recvfrom代码，避免阻塞后续发送
    # msgFromDestination= UDPSocket.recvfrom(bufferSize)
    # msg = "Message from Server {}".format(pickle.loads(msgFromDestination[0]))
    # print(msg)

def HD():
    for i in range(0,3):
        SendSocket(pickle.dumps(i), EnginePort)
        print(f'Sent packet {i}')

while True:
    HD()

接收端（receive文件） #

添加循环逻辑，让程序持续监听UDP端口：

import socket
import pickle

# 和发送端保持一致的端口值
EnginePort = 5678

UDPSocket = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM)
AddressPort = ("127.0.0.2", EnginePort)
bufferSize = 1024

UDPSocket.bind(AddressPort)
print("UDP server up and listening")

def ReceiveSocket():
    global UDPSocket
    global bufferSize
    bytesAddressPair = UDPSocket.recvfrom(bufferSize)
    print('Received a packet')
    message = pickle.loads(bytesAddressPair[0])
    address = bytesAddressPair[1]
    clientMsg = "Message from Client:{}".format(message)
    clientIP = "Client IP Address:{}".format(address)
    print(clientMsg)
    print(clientIP)

# 循环调用，持续接收数据
while True:
    ReceiveSocket()

测试效果 #

修改后先启动接收端，再运行发送端，你会看到接收端输出类似内容：

UDP server up and listening
Received a packet
Message from Client:0
Client IP Address:('127.0.0.1', 57742)
Received a packet
Message from Client:1
Client IP Address:('127.0.0.1', 57742)
Received a packet
Message from Client:2
Client IP Address:('127.0.0.1', 57742)
...

如果你的业务确实需要发送端接收回复，只需在接收端的ReceiveSocket函数里添加回复逻辑即可，比如：

# 在接收端处理完消息后添加回复代码
reply_msg = pickle.dumps(f"Success received {message}")
UDPSocket.sendto(reply_msg, address)

这样发送端的recvfrom就能收到回复，不会阻塞后续发送流程。

内容的提问来源于stack exchange，提问作者Mohammad Razmara