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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"system suspension is detected as a blocked event loop","articleBody":"### Environment\n\n@sentry-internal/node-native-stacktrace@npm:0.2.1\n\nOn linux and macos.\n\n### Steps to Reproduce\n\n1. Enable [eventLoopBlockIntegration](https://docs.sentry.io/platforms/javascript/guides/react-router/configuration/event-loop-block/).\n2. Run node instance with eventLoopBlockIntegration enabled on Google Cloud Run with the instance in request billing mode. This will also work from a laptop.\n3. Observe EventLoopBlocked notifications every time the system suspends.\n\n### Expected Result\n\nSystem suspension should not be detected as a blocked event loop.\n\n### Actual Result\n\nSystem suspension is detected and reported as a blocked event loop\n\n### Additional information\n\nThe event loop block integration currently uses `std::chrono::system_clock::now()` for detecting when the event loop is blocked ([code](https://github.com/getsentry/sentry-javascript-node-native-stacktrace/blob/56f301aeb5be6d4084bd31683b41fd90373fb8b5/module.cc#L279)). On linux, Gcc's libstdc++ uses [`clock_gettime()`](https://www.man7.org/linux/man-pages/man3/clock_gettime.3.html) with `CLOCK_REALTIME` to or `gettimeofday()` get the time depending on the settings. The documentation specifically states that `CLOCK_MONOTONIC` can be used to ignore time when the system is suspended. The `std::chrono::steady_clock::now()` implementation on linux uses this call, but on macos [llvm's libcxx specifically chooses](https://github.com/llvm/llvm-project/blob/4ae26783724a8cb29b448920f5b4066ebbbf3a95/libcxx/src/chrono.cpp#L175-L185) `CLOCK_MONOTONIC_RAW` on that platform so that the clock tracks suspends ([docs](https://www.manpagez.com/man/3/clock_gettime_nsec_np/)). On macos you want `CLOCK_UPTIME_RAW` or `CLOCK_UPTIME_RAW_APPROX`. On windows you want [`QueryUnbiasedInterruptTimePercise()`](https://learn.microsoft.com/en-us/windows/win32/api/realtimeapiset/nf-realtimeapiset-queryunbiasedinterrupttimeprecise) or [`QueryUnbiasedInterruptTime()`](https://learn.microsoft.com/en-us/windows/win32/api/realtimeapiset/nf-realtimeapiset-queryunbiasedinterrupttime).\n\nSo basically, you need to implement a custom time function that does the right thing on each platform as there doesn't appear to be one in the standard library.","author":{"url":"https://github.com/matthew-nicholson-anrok","@type":"Person","name":"matthew-nicholson-anrok"},"datePublished":"2025-07-25T00:39:43.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/13/sentry-javascript-node-native-stacktrace/issues/13"}