如何优雅地结束SocketServer

Question

I would like to stay in the std lib if possible. All of my threads run, and the sockets will listen appropriately. I need to be able to gracefully close the sockets, but I can't seem to get back to them to shutdown properly.

Problem is, when I get to server_close() it blows up on me (see exception trace output below).

Thanks for looking!

import sys
import threading
import SocketServer


class EchoRequestHandler(SocketServer.BaseRequestHandler):

    def __init__(self, request, client_address, server):
        SocketServer.BaseRequestHandler.__init__(self, request, client_address, server)
        return

    def setup(self):
        return SocketServer.BaseRequestHandler.setup(self)

    def handle(self):
        # Echo the back to the client
        data = self.request.recv(1024)
        return

    def finish(self):
        return SocketServer.BaseRequestHandler.finish(self)


class EchoServer(SocketServer.TCPServer):

    def __init__(self, server_address, handler_class=EchoRequestHandler):
        SocketServer.TCPServer.__init__(self, server_address, handler_class)
        return

    def server_activate(self):
        SocketServer.TCPServer.server_activate(self)
        return

    def serve_forever(self):
        while True:
            self.handle_request()
        return

    def server_close(self):
        return SocketServer.TCPServer.server_close(self)



def bind_sockets(port_list):

    server_list = []
    for port in port_list:

        server = EchoServer(("", int(port)), EchoRequestHandler)
        server_thread = threading.Thread(target=server.serve_forever)
        server_thread.setDaemon(True)
        server_thread.start()
        server_list.append(server)
        print "listening on port", port

    return server_list


def main():

    port_list = [12345,54321]

    active_servers = bind_sockets(port_list)

    print "Hit Q to quit or R to reload."

    while 1:
        key_press = sys.stdin.read(1)

        if key_press == "q":
            sys.exit(2)
        elif key_press == "r":
            #We need to close gracefully so we can go on to do other stuff.
            print active_servers.__len__()
            for server in active_servers:
                server.server_close()
                print "closed"


if __name__ == "__main__":
    main()

The exception stack-trace I get is:

Exception in thread Thread-1: Traceback (most recent call last): 
File "~snip~/threading.py", line 810, in __bootstrap_inner self.run() 
File "~snip~/threading.py", line 763, in run self.__target(*self.__args, **self.__kwargs) 
File "kill_thread.py", line 36, in serve_forever self.handle_request() 
File "~snip~/SocketServer.py", line 276, in handle_request fd_sets = _eintr_retry(select.select, [self], [], [], timeout) 
File "~snip~/SocketServer.py", line 155, in _eintr_retry return func(*args) error: (9, 'Bad file descriptor')

Answer 1

You have two problems:

• you need to call shutdown()
• You shouldn't override server_forever()

like this:

# don't overrule server_forever, the default implementation
# handles the shutdown()
#def serve_forever(self):
#    while True:
#        self.handle_request()
#    return

def server_close(self):
    self.shutdown()
    return SocketServer.TCPServer.server_close(self)