Question

我在绳子的尽头 - 我无法想出这一点。我是Python的新手，我正在编写一个TCP服务器/客户端应用程序。

服务器侦听连接并生成一个线程来处理连接。通信非常简单 - 客户端建立连接，发送消息，服务器响应然后关闭连接（ala HTTP）

问题是我的服务器代码不能始终从客户端接收任何数据。服务器接受新连接，旋转新线程，然后阻止.recv方法。

服务器侦听器

class TCPListener(threading.Thread):

    def __init__(self, ip = settings.BIND_IP, port = settings.BIND_PORT):
        super(TCPListener, self).__init__()
        self.daemon = True
        self._port = port
        self._ip = ip
        self.stop = threading.Event()
        self.stop.clear()

        self.tcp_server_socket = socket(AF_INET, SOCK_STREAM)
        self.tcp_server_socket.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
        self.tcp_server_socket.setblocking(False)
        self.tcp_server_socket.bind((self._ip, self._port))

    def run(self):
        # Listen for client connection requests
        with lock:
            utils.log_message("Listening for ledger messages on port {0}".format(self._port))

        try:
            self.tcp_server_socket.listen(5)

            # List for managing spawned threads
            socket_threads = []

            # Non-blocking socket loop that can be interrupted with a signal/event
            while True and not self.stop.is_set():
                try:
                    client_socket, address = self.tcp_server_socket.accept()

                    # Spawn thread
                    client_thread = TCPConnectionThread(client_socket)
                    client_thread.start()
                    socket_threads.append(client_thread)

                except Exception as e:
                    continue

            # Clean up all the threads
            for thread in socket_threads:
                thread.join()

        except Exception as e:
            print("Could not bind to port: {0}".format(e))
        finally:
            self.tcp_server_socket.close()

服务器连接处理程序

class TCPConnectionThread(threading.Thread):

    def __init__(self, socket):
        super(TCPConnectionThread, self).__init__()
        with lock:
            utils.log_message("Spawning TCP Connection Thread from {0}".format(socket.getsockname()))
        self._socket = socket


    def run(self): 
        # Get message
        message = ''
        data = True
        while data:
            data = self._socket.recv(4096)  #BLOCKS HERE 99% OF THE TIME
            message+=data.decode()

        with lock:
            utils.log_message("Received message from {0}:\n{1}".format(self._socket.getsockname(), message))

        self._socket.sendall(response)
        self._socket.close()

从我的客户端处理连接的线程只是阻塞。如果我在该点（socket.recv）上放置一个断点，它可能会收到数据，但如果我正常运行它会无限期地阻塞。我不确定为什么调试它会影响它，也许会引入延迟？我可以在wireshark中看到客户端正在发送消息而服务器确认它，但它永远不会从recv（）返回。

非常感谢任何帮助。我浪费了太多时间在最有可能是一个简单的bug上。

Answer 1

self._socket.recv是一个阻止通话。它将阻塞，直到它在套接字上接收数据。我认为问题是：

data = True
while data:
            data = self._socket.recv(4096)  #BLOCKS HERE 99% OF THE TIME
            message+=data.decode()

服务器接收数据但又进入循环并等待进一步的数据。退出循环的标准是什么？如果客户端发送数据但未断开连接，则循环将始终处于活动状态。只有当客户端断开连接时，循环才会中断。

Answer 2

我相信你为自己制造的事情过于复杂。请参阅Python Cookbook中的以下示例：

from socket import AF_INET, SOCK_STREAM, socket
from concurrent.futures import ThreadPoolExecutor

def echo_client(sock, client_addr):
    '''
    Handle a client connection
    '''
    print('Got connection from', client_addr)
    while True:
        msg = sock.recv(65536)
        if not msg:
            break
        sock.sendall(msg)
    print('Client closed connection')
    sock.close()

def echo_server(addr):
    print('Echo server running at', addr)
    pool = ThreadPoolExecutor(128)
    sock = socket(AF_INET, SOCK_STREAM)
    sock.bind(addr)
    sock.listen(5)
    while True:
        client_sock, client_addr = sock.accept()
        pool.submit(echo_client, client_sock, client_addr)

echo_server(('',15000))

至少这个：

    while True:
        msg = sock.recv(65536)
        if not msg:
            break

应该处理你的阻止问题。

Python TCP服务器接受新套接字，但从不接收数据

2 个答案: