Add split phase metrics for filestream fsync operations - #10493
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valyala merged 5 commits intoApr 2, 2026
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## Summary This PR implements split phase metrics for filestream operations as requested in VictoriaMetrics#10432. ### Changes - Added `vm_filestream_fsync_duration_seconds_total` metric to track fsync syscall duration separately - Added `vm_filestream_fsync_calls_total` metric to count fsync calls - Added `vm_filestream_write_syscall_duration_seconds_total` metric to track write syscall duration (previously mixed with flush time) - Refactored `MustClose()` and `MustFlush()` to use new `flush()` and `sync()` helper methods - Kept `vm_filestream_write_duration_seconds_total` for backward compatibility ### Problem Solved Previously, `vm_filestream_write_duration_seconds_total` was being incremented in two places: 1. `statWriter.Write()` - triggered by `bw.Flush()` and `bw.Write()` 2. `Writer.MustFlush()` - which included the above process, leading to double-counting This made it impossible to distinguish between write syscall time and fsync time, which is critical for diagnosing storage latency issues. ### Solution The new metrics allow users to: - Distinguish "flush got slower" vs "fsync got slower" using metrics only - No file path labels (bounded cardinality) - No double-counting between metrics Closes VictoriaMetrics#10432
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Signed-off-by: Aliaksandr Valialkin <[email protected]>
valyala
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Apr 2, 2026
Signed-off-by: Aliaksandr Valialkin <[email protected]>
Signed-off-by: Aliaksandr Valialkin <[email protected]>
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@mehrdadbn9 , thank you for the pull request! |
valyala
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## Summary This PR implements split phase metrics for filestream operations as requested in #10432. ### Changes - Added `vm_filestream_fsync_duration_seconds_total` metric to track fsync syscall duration separately - Added `vm_filestream_fsync_calls_total` metric to count fsync calls - Added `vm_filestream_write_syscall_duration_seconds_total` metric to track write syscall duration (previously mixed with flush time) - Refactored `MustClose()` and `MustFlush()` to use new `flush()` and `sync()` helper methods - Kept `vm_filestream_write_duration_seconds_total` for backward compatibility ### Problem Solved Previously, `vm_filestream_write_duration_seconds_total` was being incremented in two places: 1. `statWriter.Write()` - triggered by `bw.Flush()` and `bw.Write()` 2. `Writer.MustFlush()` - which included the above process, leading to double-counting This made it impossible to distinguish between write syscall time and fsync time, which is critical for diagnosing storage latency issues. ### Solution The new metrics allow users to: - Distinguish "flush got slower" vs "fsync got slower" using metrics only - No file path labels (bounded cardinality) - No double-counting between metrics ### Testing - Code compiles successfully - All existing metrics are preserved for backward compatibility Closes #10432 --------- Signed-off-by: Aliaksandr Valialkin <[email protected]> Signed-off-by: Aliaksandr Valialkin <[email protected]> Co-authored-by: Aliaksandr Valialkin <[email protected]> Co-authored-by: Aliaksandr Valialkin <[email protected]>
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Summary
This PR implements split phase metrics for filestream operations as requested in #10432.
Changes
vm_filestream_fsync_duration_seconds_totalmetric to track fsync syscall duration separatelyvm_filestream_fsync_calls_totalmetric to count fsync callsvm_filestream_write_syscall_duration_seconds_totalmetric to track write syscall duration (previously mixed with flush time)MustClose()andMustFlush()to use newflush()andsync()helper methodsvm_filestream_write_duration_seconds_totalfor backward compatibilityProblem Solved
Previously,
vm_filestream_write_duration_seconds_totalwas being incremented in two places:statWriter.Write()- triggered bybw.Flush()andbw.Write()Writer.MustFlush()- which included the above process, leading to double-countingThis made it impossible to distinguish between write syscall time and fsync time, which is critical for diagnosing storage latency issues.
Solution
The new metrics allow users to:
Testing
Closes #10432