Clarify flamegraph feature measures span timing, not CPU time#84
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Update documentation to set correct expectations: - Rename "Performance Profiling" to "Span Timing Visualization" - Explain what the feature measures (wall-clock span durations) - Document good use cases (call hierarchy, latency bottlenecks) - Note limitations (not suitable for CPU profiling async code) - Point users to CPU profiling alternatives (Instruments, samply, perf)
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Package Changes Through f92aad0There are 2 changes which include tracing with prerelease, tracing-js with prerelease Planned Package VersionsThe following package releases are the planned based on the context of changes in this pull request.
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# Version Updates Merging this PR will release new versions of the following packages based on your change files. # tracing ## [0.2.0-canary.20] - 061b015 (#84 by @johncarmack1984) Clarify that the flamegraph feature measures span timing (wall-clock time), not CPU time. Updated documentation with appropriate use cases and limitations. - 675d209 (#82 by @johncarmack1984) Switch to public package publishing: Rust on crates.io, npm with public access. # tracing-js ## [0.2.0-canary.20] - 061b015 (#84 by @johncarmack1984) Clarify that the flamegraph feature measures span timing (wall-clock time), not CPU time. Updated documentation with appropriate use cases and limitations. - 675d209 (#82 by @johncarmack1984) Switch to public package publishing: Rust on crates.io, npm with public access. Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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johncarmack1984
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Jan 14, 2026
# Version Updates Merging this PR will release new versions of the following packages based on your change files. # tracing ## [0.3.0] - 061b015 (#84 by @johncarmack1984) Clarify that the flamegraph feature measures span timing (wall-clock time), not CPU time. Updated documentation with appropriate use cases and limitations. - b059e9f (#73 by @johncarmack1984) Release 0.2.0 stable. **Highlights:** - Add `flamegraph` feature for performance profiling with flamegraph/flamechart generation - Add `WebviewLayer` for custom subscriber setups - Add file logging with rotation (`with_file_logging()`, `with_rotation()`, `with_max_file_size()`) - Add `StripAnsiWriter` for clean file output when using colored terminal output - Add custom filter support (`filter()`) and custom layer support (`with_layer()`) - Add format options (`with_format()`, `with_file()`, `with_line_number()`, etc.) - Add timezone strategy for log timestamps - Add per-target log level filtering (`with_target()`) - Add `takeoverConsole()` for full console integration (JS → Rust → browser) - Add `interceptConsole()` and `attachConsole()` for flexible console routing - Add early initialization support for flamegraph (`create_flame_layer_with_path()`) - Add clippy lints to deny `unwrap()`/`expect()` in production code - Remove `timing` feature (use native `console.time()` or tracing spans instead) - 829732c (#87 by @johncarmack1984) Remove private registry configuration. - 437dab0 (#85 by @johncarmack1984) Shorten README, link to docs.rs for details. - 675d209 (#82 by @johncarmack1984) Switch to public package publishing: Rust on crates.io, npm with public access. # tracing-js ## [0.3.0] - 061b015 (#84 by @johncarmack1984) Clarify that the flamegraph feature measures span timing (wall-clock time), not CPU time. Updated documentation with appropriate use cases and limitations. - b059e9f (#73 by @johncarmack1984) Release 0.2.0 stable. **Highlights:** - Add `flamegraph` feature for performance profiling with flamegraph/flamechart generation - Add `WebviewLayer` for custom subscriber setups - Add file logging with rotation (`with_file_logging()`, `with_rotation()`, `with_max_file_size()`) - Add `StripAnsiWriter` for clean file output when using colored terminal output - Add custom filter support (`filter()`) and custom layer support (`with_layer()`) - Add format options (`with_format()`, `with_file()`, `with_line_number()`, etc.) - Add timezone strategy for log timestamps - Add per-target log level filtering (`with_target()`) - Add `takeoverConsole()` for full console integration (JS → Rust → browser) - Add `interceptConsole()` and `attachConsole()` for flexible console routing - Add early initialization support for flamegraph (`create_flame_layer_with_path()`) - Add clippy lints to deny `unwrap()`/`expect()` in production code - Remove `timing` feature (use native `console.time()` or tracing spans instead) - 829732c (#87 by @johncarmack1984) Remove private registry configuration. - 437dab0 (#85 by @johncarmack1984) Shorten README, link to docs.rs for details. - 675d209 (#82 by @johncarmack1984) Switch to public package publishing: Rust on crates.io, npm with public access. Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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Summary
This sets correct expectations for users who might otherwise expect traditional CPU profiling.