套接字客户端断开连接后，Python线程保持活动状态

如何解决套接字客户端断开连接后，Python线程保持活动状态

我试图在运行Raspbian的Raspberry Pi 4和运行Windows 10的PC之间使用Python中的套接字来设置客户端/服务器。我的服务器脚本计算每次客户端连接时活动线程的数量。当我使用客户端脚本连接和断开连接时，活动线程数一直在增加。我在网上看了一下，发现杀死一个活动线程通常是不好的做法。如果我通过反复地将Raspberry pi客户端与PC服务器连接和断开连接来增加活动线程数，这会占用处理时间吗？有没有一种干净的方法来终止活动线程？您可以在下面查看我用于测试的客户端和服务器程序：

server.py

import socket
import threading
import multiprocessing
from commands import run_command
import time

HEADER = 64
PORT = 5050
SERVER = [IP Address]
ADDR = (SERVER,PORT)
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "!DISCONNECT"


def handle_client(conn,addr):

    print(f"[NEW CONNECTION] {addr} connected")

    connected = True
    while connected:
        msg_length = conn.recv(HEADER).decode(FORMAT)
        if msg_length:
            msg_length = int(msg_length)
            msg = conn.recv(msg_length).decode(FORMAT)
            if msg == DISCONNECT_MESSAGE:
                connect = False
                print("disconnected")
            print(f"[{addr}] {msg}")
            run_command(msg)
        time.sleep(0.001)
    conn.close()


def start():
    print("[STARTING] Server is starting...")
    server.listen()
    print(f"[LISTENING] Server is listening on {SERVER}")
    while True:
        conn,addr = server.accept()
        # thread = multiprocessing.Process(target=handle_client,args=(conn,addr))
        thread = threading.Thread(target=handle_client,addr))
        thread.start()
        # print(multiprocessing.active_children)
        print(f"[ACTIVE CONNECTIONS] {threading.activeCount() - 1}")


if __name__ == "__main__":

    server = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    server.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
    server.bind(ADDR)
    start()

client.py

import socket

HEADER = 64
PORT = 5050
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "!DISCONNECT"
SERVER = [IP Address]
ADDR = (SERVER,PORT)

class ServerClient():

    def __init__(self):
        self.client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        self.client.setsockopt(socket.SOL_SOCKET,1)
        self.client.settimeout(.5)
        try:
            self.client.connect(ADDR)
            print("Connected to server")
        except (socket.timeout,BlockingIOError) as e:
            print("Could not connect to server")

    def send_message(self,msg):
        try:
            message = msg.encode(FORMAT)
            msg_length = len(message)
            send_length = str(msg_length).encode(FORMAT)
            send_length += b' ' * (HEADER - len(send_length))
            self.client.send(send_length)
            self.client.send(message)
            print(f"Message sent to server: {msg}")
        except (socket.timeout,TimeoutError) as e :
            print("could not send message to server")
    
    def disconnect(self):
        try:
            self.send_message(DISCONNECT_MESSAGE)
            self.client.shutdown(socket.SHUT_RDWR)
            self.client.close()
            print("Disconnected from server")
        except socket.timeout:
            print("Could not disconnect from server")


if __name__ == "__main__":
    sc = ServerClient()
    sc.send_message("lol")
    sc.disconnect()

正如您在上面看到的，我已经尝试使用： self.client.setsockopt(socket.SOL_SOCKET,1) 这似乎并不能解决问题（如果有的话）。

任何帮助将不胜感激！

解决方法

您的代码通常看起来不错。仅有两个小发现：

connected = True
while connected:
    msg_length = conn.recv(HEADER).decode(FORMAT)
    if msg_length:
        msg_length = int(msg_length)
        msg = conn.recv(msg_length).decode(FORMAT)
        if msg == DISCONNECT_MESSAGE:
            connect = False     # Wrong variable used here
            print("disconnected")
        print(f"[{addr}] {msg}")
        run_command(msg)
    time.sleep(0.001)
conn.close()

在这一部分，您设置connect = False而不是connected = False，这意味着while循环永不中断。可以单独解决问题的解决方案。

现在编写代码时，在收到断开连接后，您还将执行一次run_command()。如果这是故意的，那么一切都很好。如果您不想这样做，请将continue添加到条件中以立即退出循环。

但是，您的代码可能无法从客户端错误或断开的连接中恢复。如果服务器断开连接，您的服务器只会进入一个繁忙循环，但这是我留给您解决的问题。

您实际上可以通过完全消除连接变量来解决这两个问题。只需使其while True循环，然后break断开连接或出现任何套接字错误即可。