scope-tracer

Visualize Java structured concurrency (StructuredTaskScope) task trees, lifetimes, and cancellation propagation. Zero-code-change with a Java agent, or a thin wrapper — either way you get a self-contained HTML report with SVG Gantt timelines, built from a JFR recording. Targets JDK 26+.

View an example report → Source on GitHub

What you get

Per-scope Gantt timeline — what ran in parallel, at a glance
Nested scopes rendered indented beneath the task that spawned them
Critical-path highlighting — the task that determined total scope duration
Failure and cancellation propagation, with exception details
No server required — the report is a single self-contained HTML file

Zero-code-change tracing

java --enable-preview \
     -javaagent:scope-tracer-agent-VERSION-agent.jar \
     -XX:StartFlightRecording=filename=myapp.jfr,dumponexit=true \
     -cp <your-classpath> com.example.MyApp

Any JDK 26+ application using StructuredTaskScope gets traced — no source changes. See the README for the library wrapper (TracedScope), capture filters/sampling for production use, and full setup instructions.