flamegraph

flamegraph

Generate a static call-graph flamegraph website for the Java project the user is working on.

Steps

1. Find the Java source root. Prefer src/main/java; if absent, use the directory the user points at or the closest directory containing .java files. If the user names a specific module or subproject, scope to it.

2. Run the generator that ships with this skill:

   python3 ~/.claude/skills/flamegraph/build_flamegraph.py <java-src-dir> <out-dir> [title]
   

   Use flamegraph-site inside the target project as <out-dir> unless the user asks for another location, and pass the project name as the title.

3. The script writes a single self-contained index.html. Serve it with python3 -m http.server from <out-dir> (pick a free port) or tell the user to open the file directly, then report the URL or path.

4. Tell the user how to use the site: the left panel lists every class and method, the search box filters it, clicking any method roots the flamegraph at that method, clicking a frame re-roots into it, and the breadcrumb trail walks back up. Frame width is proportional to the number of distinct call paths underneath, hovering shows file, line, and fan-in/fan-out, and a ↺ mark means a recursive cycle was pruned.

Notes

• The site is light themed and hand-drawn in style: wobbly SVG frames, pastel fills per class, handwriting fonts.
• The call graph is static: it is resolved from source text via field, parameter, and local-variable types, so dynamic dispatch through interfaces resolves only when the declared type itself defines the method.
• The generator needs only the Python standard library; do not install anything.
• If the script reports no methods found, confirm the path actually contains .java files before retrying.