Make sure that the accept() in backend.tcp does not block the process

platypush/backend/tcp.py

@@ -1,5 +1,8 @@
+import multiprocessing
+import queue
 import socket
 import threading
+from typing import Optional
 
 from platypush.backend import Backend
 from platypush.message import Message
@@ -31,6 +34,8 @@ class TcpBackend(Backend):
         self.port = port
         self.bind_address = bind_address or '0.0.0.0'
         self.listen_queue = listen_queue
+        self._accept_queue = multiprocessing.Queue()
+        self._srv: Optional[multiprocessing.Process] = None
 
     def _process_client(self, sock, address):
         def _f():
@@ -89,6 +94,14 @@ class TcpBackend(Backend):
 
         threading.Thread(target=_f_wrapper, name='TCPListener').start()
 
+    def _accept_process(self, serv_sock: socket.socket):
+        while not self.should_stop():
+            try:
+                (sock, address) = serv_sock.accept()
+                self._accept_queue.put((sock, address))
+            except socket.timeout:
+                continue
+
     def run(self):
         super().run()
         self.register_service(port=self.port)
@@ -102,16 +115,23 @@ class TcpBackend(Backend):
                          format(self.port, self.bind_address))
 
         serv_sock.listen(self.listen_queue)
+        self._srv = multiprocessing.Process(target=self._accept_process, args=(serv_sock,))
+        self._srv.start()
 
         while not self.should_stop():
             try:
-                (sock, address) = serv_sock.accept()
-            except socket.timeout:
+                sock, address = self._accept_queue.get(timeout=1)
+            except (socket.timeout, queue.Empty):
                 continue
 
             self.logger.info('Accepted connection from client {}'.format(address[0]))
             self._process_client(sock, address)
 
+        if self._srv:
+            self._srv.kill()
+            self._srv.join()
+            self._srv = None
+
         self.logger.info('TCP backend terminated')