Hang in a custom view

[alexr00]

I think it happened when I was trying to expand the explorer view from hidden.

Enabled extensions that have a view in the explorer viewlet: Docker explorer

Stack:

event.ts:429 [bf1] potential listener LEAK detected, having 1495 listeners already. MOST frequent listener (1321): e.check @ event.ts:429 Object.defineProperty.get._event._event @ event.ts:509 i @ event.ts:31 (anonymous) @ treeModel.ts:86 e.run @ treeModel.ts:85 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 (anonymous) @ treeModel.ts:87 (anonymous) @ event.ts:40 e.fire @ event.ts:562 e.dispose @ treeModel.ts:34 (anonymous) @ treeModel.ts:104 _tickCallback @ internal/process/next_tick.js:68 Promise.then (async) e.run @ treeModel.ts:102 e.run @ treeModel.ts:94 e.refreshChildren @ treeModel.ts:532 e.doRefresh @ treeModel.ts:542 e.refresh @ treeModel.ts:550 e.refresh @ treeModel.ts:1021 e.refresh @ treeImpl.ts:161 (anonymous) @ customView.ts:511 t.doRefresh @ customView.ts:511 t.setVisibility @ customView.ts:339 t.updateTreeVisibility @ customView.ts:99 (anonymous) @ customView.ts:65 e.fire @ event.ts:562 t.setVisible @ panelViewlet.ts:89 (anonymous) @ viewsViewlet.ts:195 t.setVisible @ viewsViewlet.ts:195 t.setVisible @ explorerViewlet.ts:239 t.showComposite @ compositePart.ts:283 t.doOpenComposite @ compositePart.ts:146 t.openComposite @ compositePart.ts:110 n.doOpenViewlet @ sidebarPart.ts:224 n.openViewlet @ sidebarPart.ts:180 t.run @ activitybarActions.ts:69 t.runAction @ actions.ts:209 t.run @ actions.ts:201 t.onClick @ actionbar.ts:169 (anonymous) @ actionbar.ts:139 runCallback @ timers.js:696 tryOnImmediate @ timers.js:667 processImmediate @ timers.js:649

[sandy081]

Steps to verify:

• Implement an extension that contributes a tree to the explorer
• For every 500ms fire onDidChangeTreeData event by passing null (root)
• Open VS Code and open the tree that is contributed above
• Hide the explorer
• After 5 minutes, open the explorer
• Verify that there is no hang and also your extension is called only once for the root children for all the times you fired the event till then.

You can use the following sample code

'use strict';

import * as vscode from 'vscode';

export function activate(context: vscode.ExtensionContext) {
    const emitter = new vscode.EventEmitter();
    setInterval(() => emitter.fire(null), 500);
    vscode.window.registerTreeDataProvider('testView', <vscode.TreeDataProvider<string>>{
        onDidChangeTreeData: emitter.event,
        getChildren: (element?: string): string[] => {
            if (!element) {
                return ['a', 'b'];
            }
        },
        getTreeItem: (element: string): vscode.TreeItem => {
            return new vscode.TreeItem(element, vscode.TreeItemCollapsibleState.None);
        }
    });
}

Do not forget to register the tree in package.json