Clean up handlers and remove bus listeners on v3.close() #1418

miguelg719 · 2025-12-15T20:19:53Z

why

With many concurrent sessions, memory leaks can crash the node process

what changed

Ensured handler cleanup as well as removed eventbus listeners when calling stagehand.close()

test plan

Summary by cubic

Fully clean up V3 on close to prevent memory leaks and stuck handlers. We remove event bus listeners and clear local state during teardown.

Bug Fixes
- Remove all event bus listeners on close.
- Reset act/extract/observe handlers and clear history.
- Ensure instance is removed from the global registry.

^{Written for commit 6330dde. Summary will update automatically on new commits.}

changeset-bot · 2025-12-15T20:19:56Z

🦋 Changeset detected

Latest commit: 6330dde

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@browserbasehq/stagehand	Patch
@browserbasehq/stagehand-evals	Patch
@browserbasehq/stagehand-server	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

greptile-apps · 2025-12-16T00:37:23Z

Greptile Overview

Greptile Summary

Fixed memory leaks in concurrent session scenarios by properly cleaning up resources in v3.close(). The changes ensure event bus listeners are removed and handler references are cleared when a V3 instance is closed.

Added this.bus.removeAllListeners() to prevent lingering event listeners
Cleared _history array to free accumulated data
Set actHandler, extractHandler, and observeHandler to null to release handler instances
All cleanup is in a try-catch to ensure it doesn't fail the close operation

Confidence Score: 5/5

This PR is safe to merge - straightforward cleanup logic that prevents memory leaks
The changes add proper resource cleanup in the close() method without altering any existing logic. All new cleanup code is wrapped in try-catch blocks to prevent failures, and the changes directly address the stated memory leak issue. The event bus is properly cleaned up, handlers are dereferenced, and history is cleared.
No files require special attention

Important Files Changed

File Analysis

Filename	Score	Overview
packages/core/lib/v3/v3.ts	5/5	Added cleanup for event bus listeners and handler references in `close()` to prevent memory leaks
.changeset/orange-peaches-happen.md	5/5	Standard changeset file documenting the memory leak fix

Sequence Diagram

sequenceDiagram
    participant User
    participant V3
    participant Bus as EventEmitter
    participant Handlers as Act/Extract/Observe Handlers
    participant Registry as V3._instances

    User->>V3: close()
    activate V3
    
    Note over V3: Close API client, session logger
    
    V3->>V3: ctx.close()
    Note over V3: Close CDP context & Chrome
    
    V3->>V3: Reset state to UNINITIALIZED
    V3->>V3: unbindInstanceLogger()
    
    rect rgb(200, 220, 255)
        Note over V3,Handlers: New cleanup to prevent memory leaks
        V3->>Bus: removeAllListeners()
        Note over Bus: Clear all event listeners
        
        V3->>V3: _history = []
        Note over V3: Free accumulated data
        
        V3->>Handlers: actHandler = null
        V3->>Handlers: extractHandler = null
        V3->>Handlers: observeHandler = null
        Note over Handlers: Release handler references
    end
    
    V3->>Registry: _instances.delete(this)
    Note over Registry: Remove from global registry
    
    deactivate V3
    User-->>V3: close() complete

greptile-apps

_{1 file reviewed, no comments}

_{Edit Code Review Agent Settings | Greptile}

cubic-dev-ai

No issues found across 2 files

@tkattkat

Clean up handlers and remove bus listeners on v3.close()

6330dde

miguelg719 marked this pull request as ready for review December 16, 2025 00:34

greptile-apps bot reviewed Dec 16, 2025

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cubic-dev-ai bot reviewed Dec 16, 2025

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seanmcguire12 approved these changes Dec 16, 2025

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miguelg719 merged commit 934f492 into main Dec 16, 2025
19 checks passed

This was referenced Dec 16, 2025

Version Packages #1414

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Version Packages CloudEngineHub/stagehand#1

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Clean up handlers and remove bus listeners on v3.close() #1418

Clean up handlers and remove bus listeners on v3.close() #1418

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miguelg719 commented Dec 15, 2025 •

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Clean up handlers and remove bus listeners on v3.close() #1418

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miguelg719 commented Dec 15, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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why

what changed

test plan

Summary by cubic

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changeset-bot bot commented Dec 15, 2025

🦋 Changeset detected

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greptile-apps bot commented Dec 16, 2025

Greptile Overview

Greptile Summary

Confidence Score: 5/5

Important Files Changed

Sequence Diagram

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miguelg719 commented Dec 15, 2025 •

edited

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