Address review comments

Author: pythonspeed

cheroot/server.py

@@ -1520,6 +1520,11 @@ def _close_kernel_socket(self):
                 raise
 
 
+# Unique identifier used to indicate the thread that handles unservicable
+# connections should shut down.
+_SHUT_DOWN_UNSERVICABLES_THREAD = object()
+
+
 class HTTPServer:
     """An HTTP server."""
 
@@ -1872,23 +1877,30 @@ def _serve_unservicable(self):
         """Serve connections we can't handle a 503."""
         while self.ready:
             conn = self._unservicable_conns.get()
-            if conn is None:
+            if conn is _SHUT_DOWN_UNSERVICABLES_THREAD:
                 return
             request = HTTPRequest(self, conn)
             try:
                 request.simple_response('503 Service Unavailable')
+            except (socket.error, errors.FatalSSLAlert):
+                # We're sending the 503 error to be polite, it it fails that's
+                # fine.
+                continue
             except Exception as ex:
                 self.server.error_log(
                     repr(ex),
                     level=logging.ERROR,
                     traceback=True,
                 )
-            conn.linger = True
             conn.close()
 
     def serve(self):
         """Serve requests, after invoking :func:`prepare()`."""
+        # This thread will handle unservicable connections, as added to
+        # self._unservicable_conns queue. It will run forever, until
+        # self.stop() tells it to shut down.
         threading.Thread(target=self._serve_unservicable).start()
+
         while self.ready and not self.interrupt:
             try:
                 self._connections.run(self.expiration_interval)
@@ -2221,7 +2233,11 @@ def stop(self):  # noqa: C901  # FIXME
             return  # already stopped
 
         self.ready = False
-        self._unservicable_conns.put(None)
+
+        # This tells the thread that handles unservicable connections to shut
+        # down:
+        self._unservicable_conns.put(_SHUT_DOWN_UNSERVICABLES_THREAD)
+
         if self._start_time is not None:
             self._run_time += time.time() - self._start_time
         self._start_time = None

cheroot/test/test_server.py

@@ -602,5 +602,5 @@ def test_overload_results_in_suitable_http_error(request):
     # requests fail:
     httpserver.requests._queue.put(None)
 
-    response = requests.get(f'http://127.0.0.1:{port}', timeout=20)
-    assert response.status_code == HTTPStatus.SERVICE_UNAVAILABLE.value
+    response = requests.get(f'http://{localhost}:{port}', timeout=20)
+    assert response.status_code == HTTPStatus.SERVICE_UNAVAILABLE