chromedevtools--chrome-devtools-mcp
mehmet turac
c1736a071b
## Summary - Update the memory leak debugging skill to prefer the built-in heap snapshot tools. - Add guidance for comparing snapshots, inspecting retainers, and closing loaded snapshots. - Keep memlab and the fallback comparison script as external fallback paths. Issue #2329. ## Validation - `git diff --check origin/main...HEAD` - `npm run check-format`
59 行
3.8 KiB
Markdown
59 行
3.8 KiB
Markdown
---
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name: memory-leak-debugging
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description: Diagnoses and resolves memory leaks in JavaScript/Node.js applications. Use when a user reports high memory usage, OOM errors, or wants to capture, compare, or inspect heap snapshots with Chrome DevTools MCP memory tools.
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---
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# Memory Leak Debugging
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This skill provides expert guidance and workflows for finding, diagnosing, and fixing memory leaks in JavaScript and Node.js applications using Chrome DevTools MCP.
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## Core Principles
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- **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.
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- **Isolate the Leak:** Determine if the leak is in the browser (client-side) or Node.js (server-side).
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- **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._
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- **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.
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## Workflows
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### 1. Capturing Snapshots
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When investigating a frontend web application memory leak, utilize the `chrome-devtools-mcp` tools to interact with the application and take snapshots.
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- Use tools like `click`, `navigate_page`, `fill`, etc., to manipulate the page into the desired state.
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- Revert the page back to the original state after interactions to see if memory is released.
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- Repeat the same user interactions 10 times to amplify the leak.
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- Use `take_heapsnapshot` to save `.heapsnapshot` files to disk at baseline, target (after actions), and final (after reverting actions) states.
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### 2. Comparing Snapshots
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Once you have generated `.heapsnapshot` files using `take_heapsnapshot`, compare them with Chrome DevTools MCP memory tools.
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- Start with `get_heapsnapshot_summary` for each snapshot to confirm that the files load and to compare high-level totals.
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- Use `compare_heapsnapshots` to compare baseline and target snapshots. Start without `classIndex` for the summary diff, then request detailed class diffs only for suspicious growth.
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- Use the summary output from `compare_heapsnapshots` before drilling into specific node IDs.
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### 3. Inspecting Retainers
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When a class or object type grows unexpectedly, inspect the retaining chain with the MCP tools before changing code.
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- Use `get_heapsnapshot_class_nodes` to list instances of the suspicious class.
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- Use `get_heapsnapshot_retainers`, `get_heapsnapshot_retaining_paths`, `get_heapsnapshot_dominators`, and `get_heapsnapshot_edges` to understand why representative nodes are still reachable.
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- Use `get_heapsnapshot_duplicate_strings` when string growth dominates the diff.
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- Read [references/common-leaks.md](references/common-leaks.md) for examples of common memory leaks and how to fix them after the retaining path points at application code.
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### 4. External Tool Fallback
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If the built-in MCP memory tools are not enough, use external tools as a fallback rather than reading raw snapshots directly.
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- Read [references/memlab.md](references/memlab.md) for how to use `memlab` to analyze generated heap snapshots.
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- If `memlab` is not available, use the fallback script in the references directory to compare two `.heapsnapshot` files and identify the top growing objects and common leak types.
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Run the fallback script using Node.js:
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```bash
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node skills/memory-leak-debugging/references/compare_snapshots.js <baseline.heapsnapshot> <target.heapsnapshot>
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```
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The script will analyze and output the top growing objects by size and highlight the 3 most common types of memory leaks (for example, detached DOM nodes, closures, and contexts) if they are present.
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