Python SocketServer deadlock issue

Question

When I'm threading the SocketServer instance (the serve_forever method) I can quit it easily when sending the text "shutdown", which is what I expect. However, if its not threaded then I run into the issue of it locking up and I can't figure out how to get around this.

The basic flow of the server itself is start->listen->get data->get the command from it->run the command (which is a plugin)->return the results. Here's the code I use:

import SocketServer as SS

NULL_RESP = {"status" : False, "data" : "No data received."}

class ASWCP_Daemon(SS.BaseRequestHandler):
    def handle(self):
        self.data = self.request.recv(1024).strip()

        if self.data == "":
           self.request.sendall(json.dumps(NULL_RESP))
           return None

       tmp = self.data.split(" ", 1)

       cmd = tmp[0]
       args = ""

       try:
           args = str(tmp[1]).split(conf.command_parse)
    except:
           pass

       plugin = plugins["cmd"][cmd]['ref'].init(conf=conf, socket=self)

       try:
           if args[0] == "help":
            self.request.sendall(plugin.help)
       except IndexError:
           status,data = plugin.run(args)
           resp = {"status" : status, "data" : data}
           self.request.sendall(json.dumps(resp))

  if __name__ == "__main__":
   # Log is created here; conf = config file (irrelevant to this issue)

   try:
       if conf.tcp:
           if conf.threaded:
               import threading
               class ThreadedTCPServer(SS.ThreadingMixIn, SS.TCPServer):
                   pass

               server = ThreadedTCPServer((conf.host, conf.listen_port), ASWCP_Daemon)
           else:
               server = SS.TCPServer((conf.host, conf.listen_port), ASWCP_Daemon)
       else:
           server = SS.UDPServer((conf.host, conf.listen_port), ASWCP_Daemon)

       if conf.threaded:
           sthread = threading.Thread(target=server.serve_forever)
           #sthread.daemon = True
           sthread.start()
       else:
           server.serve_forever()
   except KeyboardInterrupt:
       pass

The shutdown plugin's run method is this:

    def run(self, *args, **kwargs):
        if self.socket == None:
            print "> No socket available"
            return (False,"")
        else:
            self.socket.log.info("Shutting down daemon")
            self.socket.server.shutdown()

            return (True,"")

If threaded this is fine, if its not then it gets as far as the self.socket.server.shutdown() method in the plugin. self.socket is the instance of ASWCP_Daemon class.

Can you post the *full* problematic code? This code is not correctly indented (simply paste it from the editor, highlight it, and press `Ctrl+K` here), and `conf` is not defined, and it's missing the actual shutdown, and it contains irrelevant code (anything related to threading, since the problem occurs when threading is disabled). — phihag, Jul 05 '13 at 00:53
Sorry been really busy so haven't had a chance to respond. I fixed it and made it the answer to this. — Eric Hansen, Jul 12 '13 at 13:42

score 1 · Answer 1 · answered Jul 12 '13 at 13:46

    # Do shutdown() if threaded, else execute server_close()
    if self.sysconf.threaded:
        self.socket.server.shutdown()
    else:
        self.socket.server.server_close()

    return (True,"")

self.sysconf is the configuration for the daemon (conf in the code in the question), and self.socket is a reference to the stream handler.

Python SocketServer deadlock issue

1 Answers1