Fast Java Thread

VS Code extension for analyzing JVM thread dumps (.tdump files).

Features

• Tree View Sidebar — Threads grouped by state (RUNNABLE, BLOCKED, WAITING, etc.) with counts and icons
• Dashboard — Pie chart of thread states, top 10 hot methods, deadlock alerts
• Click-to-Navigate — Click a thread in the tree to jump to its location in the dump file
• Deadlock Detection — Automatic cycle detection in lock wait graphs
• Method Search — Find all threads running a specific method, with state breakdown and lock info
• MCP Server — Expose analysis tools to AI assistants (Claude, Copilot, Cursor) via the Model Context Protocol
• Java 8 & 11+ Support — Parses both formats (with and without cpu=/elapsed= fields)

Screenshots

Usage

1. Open a .tdump file in VS Code
2. The tree view populates automatically in the Fast Java Thread sidebar
3. Right-click in the editor and select Analyze Thread Dump for full analysis
4. Run Fast Java Thread: Show Dashboard from the command palette for the webview dashboard

Commands

Command	Description
Fast Java Thread: Analyze Thread Dump	Parse the active .tdump file and populate the tree view
Fast Java Thread: Show Dashboard	Open the webview dashboard with charts and deadlock alerts

MCP Server

The extension includes an MCP server that lets AI assistants analyze thread dumps directly. It works with any MCP-compatible client — Claude Code, Claude Desktop, GitHub Copilot Chat, Cursor, etc.

Available tools

Tool	What it does
analyze_thread_dump	Full analysis: thread states, hot methods, and deadlock detection
detect_deadlocks	Focused deadlock cycle detection with lock chain details
get_hot_methods	Most frequently occurring methods across all stack traces
get_thread_summary	Quick overview: thread count, state breakdown, deadlock count
find_threads_by_method	Find threads running a specific method, with state and lock info

Standalone (stdio)

Point your MCP client at the server:

node out/src/mcp/server.js

For Claude Code, add to your .mcp.json:

{
  "mcpServers": {
    "fast-java-thread": {
      "command": "node",
      "args": ["path/to/FastJavaThread/out/src/mcp/server.js"]
    }
  }
}

HTTP mode

For network access (e.g. from a Tauri app), run with HTTP transport:

node out/src/mcp/server.js --transport http --port 3100 --auth-token mytoken

VS Code settings

Setting	Default	Description
fastJavaThread.mcp.transport	stdio	Transport mode: stdio or http
fastJavaThread.mcp.port	3100	Port for HTTP transport
fastJavaThread.mcp.auth.enabled	false	Enable Bearer token auth (HTTP only)
fastJavaThread.mcp.auth.token	""	Bearer token value

Development

npm install
npm run compile
npm test

Press F5 in VS Code to launch the Extension Development Host.

File Format

The extension expects .tdump files containing standard JVM thread dump output, as produced by jstack, kill -3, or JMX ThreadMXBean.dumpAllThreads().