Fixed infinite loading after idle connection loss on Linux Desktop. #6308

Author: ZoroXL

web/pgadmin/browser/utils.py

@@ -433,7 +433,12 @@ def children(self, **kwargs):
 
         try:
             conn = manager.connection(did=did)
-            if not conn.connected():
+            # Use connection_ping() instead of connected() to detect
+            # stale / half-open TCP connections that were silently
+            # dropped while pgAdmin was idle.  connected() only checks
+            # local state and would miss these, causing the subsequent
+            # SQL queries to hang indefinitely.
+            if not conn.connection_ping():
                 status, msg = conn.connect()
                 if not status:
                     return internal_server_error(errormsg=msg)

web/pgadmin/static/js/tree/tree_nodes.ts

@@ -121,12 +121,45 @@ export class ManageTreeNodes {
     let treeData = [];
     if (url) {
       try {
-        const res = await api.get(url);
+        const res = await api.get(url, {timeout: 30000});
         treeData = res.data.data;
       } catch (error) {
         /* react-aspen does not handle reject case */
         console.error(error);
-        pgAdmin.Browser.notifier.error(parseApiError(error)||'Node Load Error...');
+        if (error.response?.status === 503 &&
+            error.response?.data?.info === 'CONNECTION_LOST') {
+          // Connection dropped while idle.  Walk up to the server node
+          // and mark it disconnected, then show a reconnect prompt so
+          // the user can re-establish instead of seeing a silent
+          // spinner.
+          let serverNode = node;
+          while (serverNode) {
+            const d = serverNode.metadata?.data ?? serverNode.data;
+            if (d?._type === 'server') break;
+            serverNode = serverNode.parentNode ?? null;
+          }
+          if (serverNode) {
+            const sData = serverNode.metadata?.data ?? serverNode.data;
+            if (sData) sData.connected = false;
+            pgAdmin.Browser.tree?.addIcon(serverNode, {icon: 'icon-server-not-connected'});
+            pgAdmin.Browser.tree?.close(serverNode);
+          }
+          pgAdmin.Browser.notifier.confirm(
+            gettext('Connection lost'),
+            gettext('The connection to the server has been lost. Would you like to reconnect?'),
+            function() {
+              // Re-open (connect) the server node in the tree which
+              // will trigger the standard connect-to-server flow
+              // including any password prompts.
+              if (serverNode && pgAdmin.Browser.tree) {
+                pgAdmin.Browser.tree.toggle(serverNode);
+              }
+            },
+            function() { /* cancelled */ }
+          );
+        } else {
+          pgAdmin.Browser.notifier.error(parseApiError(error)||'Node Load Error...');
+        }
         return [];
       }
     }

web/pgadmin/tools/sqleditor/static/js/components/QueryToolComponent.jsx

@@ -482,6 +482,36 @@ export default function QueryToolComponent({params, pgWindow, pgAdmin, selectedN
         setQtStatePartial({is_visible: false});
       } else {
         setQtStatePartial({is_visible: true});
+        // When the tab becomes visible again after being hidden (e.g. user
+        // switched away on Linux Desktop), immediately check the connection
+        // status.  This ensures a dead connection is detected right away
+        // instead of waiting for the next poll interval, which was disabled
+        // while the tab was hidden.
+        if(qtState.params?.trans_id && qtState.connected_once) {
+          fetchConnectionStatus(api, qtState.params.trans_id)
+            .then(({data: respData}) => {
+              if(respData.data) {
+                setQtStatePartial({
+                  connected: true,
+                  connection_status: respData.data.status,
+                });
+              } else {
+                setQtStatePartial({
+                  connected: false,
+                  connection_status: null,
+                  connection_status_msg: gettext('An unexpected error occurred - ensure you are logged into the application.')
+                });
+              }
+            })
+            .catch((error) => {
+              console.error(error);
+              setQtStatePartial({
+                connected: false,
+                connection_status: null,
+                connection_status_msg: parseApiError(error),
+              });
+            });
+        }
       }
     });
   }, []);

web/pgadmin/utils/driver/psycopg3/connection.py

@@ -1413,6 +1413,31 @@ def connected(self):
             self.conn = None
         return False
 
+    def connection_ping(self):
+        """
+        Check if the connection is actually alive by executing a lightweight
+        query.  Unlike connected(), which only inspects local state, this
+        sends traffic to the server and will detect stale / half-open TCP
+        connections that were silently dropped by firewalls or the OS while
+        pgAdmin was idle.
+
+        Returns True if alive, False otherwise.
+        """
+        if not self.connected():
+            return False
+        try:
+            cur = self.conn.cursor()
+            cur.execute("SELECT 1")
+            cur.close()
+            return True
+        except Exception:
+            try:
+                self.conn.close()
+            except Exception:
+                pass
+            self.conn = None
+            return False
+
     def _decrypt_password(self, manager):
         """
         Decrypt password

web/pgadmin/utils/driver/psycopg3/server_manager.py

@@ -699,6 +699,22 @@ def create_connection_string(self, database, user, password=None):
                 display_dsn_args[key] = orig_value if with_complete_path else \
                     value
 
+        # Enable TCP keepalive so that stale/half-open connections are
+        # detected by the OS within a reasonable time instead of hanging
+        # for the full TCP retransmission timeout (which can be many
+        # minutes).  These are libpq parameters passed through to
+        # setsockopt and only take effect if not already set by the user
+        # in connection_params.
+        keepalive_defaults = {
+            'keepalives': 1,
+            'keepalives_idle': 30,
+            'keepalives_interval': 10,
+            'keepalives_count': 3,
+        }
+        for k, v in keepalive_defaults.items():
+            if k not in dsn_args:
+                dsn_args[k] = v
+
         self.display_connection_string = make_conninfo(**display_dsn_args)
 
         return make_conninfo(**dsn_args)