cached entire url, per nfelt's comment

Author: mm3509

tensorboard/program.py

@@ -597,7 +597,7 @@ def __init__(self, wsgi_app, flags):
             host = "localhost"
 
         self._host = host
-        self.display_host = None  # Will be set by get_url() below
+        self._url = None  # Will be set by get_url() below
 
         self._fix_werkzeug_logging()
         try:
@@ -728,30 +728,31 @@ def handle_error(self, request, client_address):
             logger.error("HTTP serving error", exc_info=exc_info)
 
     def get_url(self):
-        if not self.display_host:
+        if not self._url:
             if self._auto_wildcard:
-                self.display_host = socket.getfqdn()
+                display_host = socket.getfqdn()
 
                 # Confirm that the connection is open, otherwise change to `localhost`
                 try:
                     socket.create_connection(
-                        (self.display_host, self.server_port), timeout=1
+                        (display_host, self.server_port), timeout=1
                     )
                 except socket.error as e:
-                    self.display_host = "localhost"
+                    display_host = "localhost"
 
             else:
                 host = self._host
-                self.display_host = (
+                display_host = (
                     "[%s]" % host
                     if ":" in host and not host.startswith("[")
                     else host
                 )
-        return "http://%s:%d%s/" % (
-            self.display_host,
-            self.server_port,
-            self._flags.path_prefix.rstrip("/"),
-        )
+            self._url = "http://%s:%d%s/" % (
+                display_host,
+                self.server_port,
+                self._flags.path_prefix.rstrip("/"),
+            )
+        return self._url 
 
     def print_serving_message(self):
         if self._flags.host is None and not self._flags.bind_all: