为什么我的Python线程中的socket并不总是正常关闭（即如果我多次运行程序）

Question

我有以下这段代码（里面有很多调试信息）。如果我在短时间内连续运行几次，常常会出现“地址正在使用”的错误。不过，这个错误并不是每次都会发生。

socket.error: [Errno 98] Address already in use

当我没有遇到错误时，输出结果是这样的：

 trying to recv ('127.0.0.1', 38041)
 recved
 from client -->  None genuine without this seal!
 shutting down con
 closing con
 done closing con
 shutting down
 running server shutdown
 running server close
 done closing
 done shutting down

以下是我的代码：

import socket
from threading import Thread
from time import sleep
from subprocess import Popen, PIPE, STDOUT


def shutdown_thread(t):
    print "shutting down"
    t.shutdown()
    while t.isAlive():
        sleep(.1)
    print "done shutting down"


def send_with_netcat(msg):
    nc = Popen(
        ['nc', '127.0.0.1', '8000'],
        stdin=PIPE,
        stdout=PIPE,
        stderr=STDOUT)

    result = nc.communicate(msg)
    return result


class Server(Thread):
    is_shutdown = False

    def __init__(self):
        super(Server, self).__init__()
        self.start_server()

    def start_server(self):
        self.server = socket.socket(
            socket.AF_INET,
            socket.SOCK_STREAM)

        # "A socket is a 5 tuple (proto, local addr, local port,
        # remote addr, remote port).  SO_REUSEADDR just says that you
        # can reuse local addresses.  The 5 tuple still must be
        # unique!"
        self.server.setsockopt(
            socket.SOL_SOCKET,
            socket.SO_REUSEADDR,
            1)

        self.server = socket.socket(
            socket.AF_INET,
            socket.SOCK_STREAM)

        # bind the socket
        # ERROR HAPPENS HERE, HOW TO DEAL DEAL WITH OR AVOID?
        self.server.bind(('127.0.0.1', 8000))
        self.server.listen(5)

    def shutdown(self):
        self.is_shutdown = True

    def run(self):
        while not self.is_shutdown:
            con, addr = self.server.accept()
            print "trying to recv", addr
            buf = con.recv(128)
            print "recved"
            if len(buf) > 0:
                print "from client --> ", buf

            print "shutting down con"
            con.shutdown(socket.SHUT_RDWR)
            print "closing con"
            con.close()
            print "done closing con"
            sleep(.1)

        print "running server shutdown"
        self.server.shutdown(socket.SHUT_RDWR)
        print "running server close"
        self.server.close()
        print "done closing"

if __name__ == '__main__':
    s = Server()
    s.start()
    send_with_netcat("None genuine without this seal!")
    shutdown_thread(s)
    sleep(5)

如果你觉得在GitHub上看起来更清晰，可以在这里查看同样的代码。

奇怪的是，当我试图发这个帖子时，花了比预期更多的时间。这会不会是因为我的机器上有很多连接在随机化客户端的nc连接呢？

感谢你对这个问题的任何解释。

error handling multithreading network programming socket debugging connection management resource cleanup address in use

为什么我的Python线程中的socket并不总是正常关闭（即如果我多次运行程序）

1 个回答

撰写回答