Chrometrace profiling support#49
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This change adds support for py-spy's native chrometrace format output, enabling timeline-based CPU profiling visualization in Perfetto UI. Backend changes: - Add 'chrometrace' to supported formats in profile_manager.py - Add 'rate' parameter for configurable sampling rate (default 100 Hz) - Update reporter_agent.py to pass rate parameter - Update reporter_head.py to set Content-Type: application/json and CORS headers for chrometrace format to allow Perfetto UI fetching Frontend changes: - Add CpuProfilingButton component with dialog for configuring: - Format: Flamegraph (SVG), Chrome Trace (Timeline), Speedscope - Duration: 1-60 seconds - Sampling Rate: 1-1000 Hz - Native: Include C/C++ stack frames (Linux only) - Add "Open in Perfetto" button for chrometrace format - Replace CpuProfilingLink with CpuProfilingButton in all pages - Replace TaskCpuProfilingLink with TaskCpuProfilingButton Protobuf changes: - Add 'rate' field to CpuProfilingRequest message Tests: - Add test_profiler_chrometrace_format test Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The "Open in Viewer" button was failing because Speedscope's URL constructor requires an absolute URL with protocol and host, but we were passing a relative path. Now we use window.location.origin to build the full absolute URL dynamically, which works regardless of how the dashboard is accessed (localhost, IP, or proxy). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Adds "Open in Perfetto" button for chrometrace format that opens ui.perfetto.dev with trace data using postMessage protocol. Includes a confirmation dialog warning users about sending data to third-party site. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Integrates the open-source chrome://tracing viewer (Catapult) directly into the Ray dashboard for fully local chrometrace visualization without sending data to external services. Changes: - Add trace-viewer/ static assets (built from Catapult project) - Add URL loading support via hash parameter (#traceURL=...) - Add "Open in Trace Viewer" button for chrometrace format - Rename existing button to "Open in Speedscope" for clarity Benefits: - Security: No profile data sent to third-party sites - Offline: Works in air-gapped environments - UX: Same experience as chrome://tracing Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Use original about_tracing.html which contains all required <template> elements (like #profiling-view-template) that the JS code needs - Rename about_tracing.js to tracing.js to match original HTML reference - Add URL loading script with hash-based traceURL parameter support Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The setActiveTrace function is asynchronous - it returns immediately but loads the model via a promise internally. Instead of hiding the overlay right after calling setActiveTrace, poll for when the timelineView.model is populated with processes before removing the loading overlay. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Use inline style.display='none' instead of classList.add('hidden')
to override the inline display:flex that has higher CSS specificity.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Remove speedscope from format dropdown, keep flamegraph and chrometrace - Add new py-spy options exposed in UI: GIL Only, Include Idle, Non-blocking - Always enable --threads flag for thread ID visibility - Update protobuf, backend API, and profile manager to support new options Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Add getBasePath() helper to extract base path from current URL - Update openInSpeedscope, openInTraceViewer, and openInPerfetto to use base path for correct URL generation behind proxy - Change CpuProfilerButton and ProfilerButton wrappers from <div> to React.Fragment to fix inline layout issues Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
lishunyao97
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Mar 13, 2026
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Very cool work! thanks for adding this
Tests cover button rendering, dialog interactions, py-spy options (native, GIL, idle, nonblocking), chrometrace viewer buttons (Speedscope, Trace Viewer, Perfetto), and default format selection. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
This PR adds Chrome Trace format support for CPU profiling in the Ray Dashboard, enabling temporal/timeline-based profiling
alongside the existing flamegraph format. Users can now choose between three visualization methods when profiling actors, tasks,
jobs, or nodes.
Key Changes
Chrome Trace format support: Added
chrometraceformat option to py-spy profiler, generating timeline-based profiles thatshow when functions execute over time
Three visualization options:
Embedded Catapult Trace Viewer: Bundled the Chromium Catapult trace-viewer for fully local visualization without sending data
to external services
Visualization Method Comparison
Key Insight: Chrome Trace Viewer is the only option that provides a unified stack view across multiple threads, making it
essential for debugging multi-threaded Python applications where understanding cross-thread timing and interactions is critical.
Files Changed
python/ray/dashboard/client/src/common/ProfilingLink.tsx- New profiling UI with format selectionpython/ray/dashboard/modules/reporter/profile_manager.py- Added chrometrace format supportpython/ray/dashboard/modules/reporter/reporter_head.py- New endpoint for trace viewerpython/ray/dashboard/client/public/trace-viewer/- Embedded Catapult trace viewersrc/ray/protobuf/reporter.proto- Added format field to protobufTest Plan
Screen.Recording.2026-03-12.at.7.19.20.PM.mov