Memory Leak Debugging

This skill provides expert guidance and workflows for finding, diagnosing, and fixing memory leaks in JavaScript and Node.js applications using Chrome DevTools MCP tools.

Prerequisites

Advanced memory debugging tools (compare_heapsnapshots, get_heapsnapshot_details, etc.) are only available when the server is started with the --memoryDebugging flag. First check if these tools are available; if not, try to read the MCP configuration file to check if --memoryDebugging is enabled.

Core Principles

• Prefer MCP memory tools: Do NOT attempt to read raw .heapsnapshot files directly, as they are extremely large and will consume too many tokens. Use the Chrome DevTools MCP heap snapshot tools to summarize, compare, and inspect snapshots.
• Isolate the Leak: Determine if the leak is in the browser (client-side) or Node.js (server-side).
• Common Culprits: Look for detached DOM nodes, unhandled closures, global variables, event listeners not being removed, and caches growing unbounded. Note: Detached DOM nodes are sometimes intentional caches; always ask the user before nulling them.
• Close Loaded Snapshots: Heap snapshots can be large. After completing an investigation, use close_heapsnapshot for each loaded snapshot to release memory held by the MCP server.

Workflows

1. Capturing Snapshots