Ensure safe access to global rand.Rand #5815
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pkwarren
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MrAlias,
XSAM,
dashpole,
MadVikingGod,
pellared,
hanyuancheung and
dmathieu
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pkwarren
commented
Sep 12, 2024
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## main #5815 +/- ##
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- Coverage 84.5% 84.5% -0.1%
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Files 272 272
Lines 22766 22778 +12
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+ Hits 19251 19258 +7
- Misses 3172 3177 +5
Partials 343 343 |
Update rand.Rand usage to add locking around a global rand.Rand instance, which is not safe for concurrent access by multiple goroutines. Fixes open-telemetry#5814.
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dmathieu
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Sep 13, 2024
Co-authored-by: Damien Mathieu <42@dmathieu.com>
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Thank you for the contribution. I've created #5819 as a replacement for this. It makes a more systemic change to the structure of random number generation in the exemplar code base. I'm going to close this as it seems to be superseded by that PR, please re-open if this is done in error. |
MrAlias
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Sep 16, 2024
Instead of using a global random number generator for all `randRes`, have each value use its own. This removes the need for locking and managing concurrent safe access to the global. Also, the field, given the `Reservoir` type is not concurrent safe and the metric pipeline guards this, does not need a `sync.Mutex` to guard it. Supersedes #5815 Fix #5814 ### Performance Analysis This change has approximately equivalent performance as the existing code based on existing benchmarks. ```terminal goos: linux goarch: amd64 pkg: go.opentelemetry.io/otel/sdk/metric cpu: Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz │ old.txt │ new.txt │ │ sec/op │ sec/op vs base │ Exemplars/Int64Counter/8-8 14.00µ ± 3% 13.44µ ± 4% -3.98% (p=0.001 n=10) │ old.txt │ new.txt │ │ B/op │ B/op vs base │ Exemplars/Int64Counter/8-8 3.791Ki ± 0% 3.791Ki ± 0% ~ (p=1.000 n=10) ¹ ¹ all samples are equal │ old.txt │ new.txt │ │ allocs/op │ allocs/op vs base │ Exemplars/Int64Counter/8-8 84.00 ± 0% 84.00 ± 0% ~ (p=1.000 n=10) ¹ ¹ all samples are equal ```
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Update rand.Rand usage to add locking around a global rand.Rand instance, which is not safe for concurrent access by multiple goroutines.
Fixes #5814.