fix: DH-18347: Increase panel debounce (#210)

DH-18347: Increase panel debounce

src/common/constants.ts

@@ -1,6 +1,15 @@
 import * as path from 'node:path';
 import type { ConsoleType, VariableType } from '../types';
 
+/**
+ * This value is a little bit arbitrary, but it needs to be long enough to
+ * allow panels to update their `visible` property after an `onDidChangeTabs`
+ * event fires. If we find that we have trouble with lazy panels not loading on
+ * initial activation, we may need to increase this value. This seems to work
+ * on a slower VM being used for testing whereas 50ms did not.
+ */
+export const DEBOUNCE_TAB_UPDATE_MS = 100;
+
 export const EXTENSION_ID = 'vscode-deephaven' as const;
 
 export const CONFIG_KEY = {

src/controllers/PanelController.ts

@@ -21,6 +21,7 @@ import {
 import { DhcService } from '../services';
 import {
   CENSORED_TEXT,
+  DEBOUNCE_TAB_UPDATE_MS,
   DEEPHAVEN_POST_MSG,
   DH_PANEL_VIEW_TYPE,
   OPEN_VARIABLE_PANELS_CMD,
@@ -74,7 +75,10 @@ export class PanelController extends ControllerBase {
    * Load any visible panels that are marked for pending initial load. Calls
    * to this method are debounced in case this is called multiple times before
    * the active tab state actually settles. e.g. tab change events may fire
-   * multiple times as tabs are removed, added, etc.
+   * multiple times as tabs are removed, added, etc. Also, on slower machines,
+   * there may be some latency between when `onDidChangeTabs` fires and
+   * `panel.visible` props are updated, so wait long enough to ensure they are
+   * current.
    */
   private _debouncedRefreshVisiblePanelsPendingInitialLoad = (): void => {
     clearTimeout(this._debounceRefreshPanels);
@@ -122,7 +126,8 @@ export class PanelController extends ControllerBase {
           this._onRefreshPanelsContent(url, [variable]);
         }
       });
-    }, 50);
+      // See comment on `_debouncedRefreshVisiblePanelsPendingInitialLoad`
+    }, DEBOUNCE_TAB_UPDATE_MS);
   };
 
   /**