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[Bug] Memory leaking when disposing Diff editor #4659

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microsoft/vscode
#230713
Open
[Bug] Memory leaking when disposing Diff editor#4659
microsoft/vscode
#230713
@samirzubi-db

Description

@samirzubi-db
samirzubi-db
opened on Aug 27, 2024

Reproducible in vscode.dev or in VS Code Desktop?

  • Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

  • Not reproducible in the monaco editor playground

Monaco Editor Playground Link

No response

Monaco Editor Playground Code

No response

Reproduction Steps

I wrote a small application demonstrating the issue:
You can find it on the following link: https://zd9n67.csb.app/
Code: https://codesandbox.io/p/sandbox/react-typescript-forked-zd9n67

Actual (Problematic) Behavior

Diff editor does not dispose correctly after being removed from the dom.
The regular editor component does not have this issue.

Initial load
initial_render

Second memory snapshot
second_take

Third memory snapshot
third_take

Fourth memory snapshot
fourth_take

The memory constantly grows as the diff editor is not properly disposed of. Form my investigation I could see that the Emitter and InteractionEmitter are constantly growing without being disposed in the monaco-editor/esm/vs/editor/browser/widget/codeEditor/codeEditorWidget.js file.
Also a lot of detached canvas dom elements like:
<canvas class="original diffOverviewRuler" ...

Expected Behavior

Diff editor gets removed properly and does not cause a memory leak.

Additional Context

We started observing the issue in the 0.44.0 version of monaco-editor as the earlier versions don't seem to have this problem. The example is for the latest version 0.51.0

Activity

alexanderwu-db

alexanderwu-db commented on Aug 27, 2024

@alexanderwu-db
alexanderwu-db
on Aug 27, 2024

Probably would be a good idea to write a unit test in the monaco editor library to test against memory leaks in the future?

samirzubi-db
linked a pull request that will close this issue on Oct 7, 2024
samirzubi-db

samirzubi-db commented on Oct 7, 2024

@samirzubi-db
samirzubi-db
on Oct 7, 2024
Author

I've submitted a fix in the vscode repo in case anyone needs to fix this in their codebase.

O10J

O10J commented on May 30, 2025

@O10J
O10J
on May 30, 2025 · edited by O10J

I'm not sure if this is directly related to a bug, but I encountered a strange behavior when switching from a DiffEditor to a regular Editor.
After disposing a DiffEditor and then creating a regular Editor, the arrow keys (← →) start moving the cursor two characters instead of one.

Here's a minimal example to reproduce the issue. Please try it in the Monaco Playground:

let editor = null;
let diffEditor = null;

function disposeEditors() {
    monaco.editor.getEditors().forEach(e => e.dispose());
    monaco.editor.getModels().forEach(m => m.dispose()); 
    editor = null;
    diffEditor = null;
}

function initializeEditor(content = "") {
    require(['vs/editor/editor.main'], function () {
		disposeEditors();
        const container = document.getElementById('container');
        container.innerHTML = ""; 
        editor = monaco.editor.create(container, {
            value: content,
        });
    });
}

function initializeDiffEditor(originalContent, modifiedContent) {
    require(['vs/editor/editor.main'], function () {
		disposeEditors();
        const container = document.getElementById('container');
        container.innerHTML = ""; 
        diffEditor = monaco.editor.createDiffEditor(container, {
        });
        const originalModel = monaco.editor.createModel(originalContent, 'plaintext');
        const modifiedModel = monaco.editor.createModel(modifiedContent, 'plaintext');
        diffEditor.setModel({ original: originalModel, modified: modifiedModel });
    });
}

initializeEditor("AABBAABB");
initializeDiffEditor("AAAA", "BBBB")
initializeEditor("AABBAABB");
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      Issue actions
        [Bug] Memory leaking when disposing Diff editor · Issue #4659 · microsoft/monaco-editor