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base repository: getsentry/sentry-javascript-profiling-node-binaries
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Commits on Aug 10, 2026

  1. fix: Create CpuProfiler lazily instead of at module load 

    v8::CpuProfiler::New was called from the addon's N-API Init, so merely
requiring the package created the profiler. In eager logging mode that
constructor walks every compiled function while holding V8's Logger mutex,
which is not recursive before V8 12.7. If an allocation during that walk
starts incremental marking, MarkCompactCollector::StartCompaction re-enters
the mutex via Isolate::AllowsCodeCompaction() and the main thread deadlocks
against itself (V8 bug 41497149). Every Node <= 22 ships an affected V8, so
the exposure window was every process start that imported the package.

The profiler is now created on the first profile start. Processes that never
profile are no longer exposed at all, and the walk is off the startup path.

Measured on a 10k-function app under Node 22.20: require drops from ~246ms to
~1ms, with that cost moving to the first startProfiling call. Profile output
is unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
    @JPeer264 @claude
    JPeer264 and claude committed Aug 10, 2026
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