perf: optimize classic-only histogram observe path#2252
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Signed-off-by: Arnab Nandy <arnab_nandy7@yahoo.com>
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Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>
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Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>
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## Summary Extract the PR benchmark workflows from #2252 into a standalone PR so they can land on `main` first. ## Why The benchmark job uploads a Markdown artifact with the PR comment contents, but the actual PR comment is posted by a separate `workflow_run` workflow. GitHub only triggers `workflow_run` workflows when the workflow file already exists on the default branch, so keeping the reporter in the same PR prevents it from commenting on that PR's benchmark run. Splitting these workflows out first lets subsequent benchmark PRs use the comment-reporting flow as intended. ## Changes - add `PR Benchmarks` workflow triggered by the `benchmark` label on pull requests - add `PR Benchmark Report` workflow triggered by `workflow_run` - keep the benchmark summary as an uploaded artifact consumed by the reporter workflow ## Testing - `mise run lint:fix`
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## Summary The `PR Benchmark Report` workflow failed to comment on [#2252](#2252) after a successful benchmark run ([run 28865892835](https://github.com/prometheus/client_java/actions/runs/28865892835)): ``` gh: Not Found (HTTP 404) parse "https://api.github.com/repos/prometheus/client_java/issues/comments/{\r": net/url: invalid control character in URL ``` Root cause: `workflow_run.pull_requests` is empty when the triggering run's head branch is not on the default branch (or the PR is from a fork). With `PR_NUMBER` empty, the subsequent `repos/${REPO}/issues//comments` API call 404s and the paginator emits a malformed URL, so no comment gets posted. ## Changes - Fall back to `repos/{owner}/{repo}/commits/{sha}/pulls` to resolve the PR from the head SHA when `workflow_run.pull_requests` is empty. - Fail fast with an explicit error if the PR still can't be resolved, so future regressions don't cascade into cryptic URL-parse errors. ## Test plan - [ ] Re-run the report workflow against run 28861406560 (or a fresh push to #2252) and confirm a benchmark comment lands on the PR. Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>
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Summary
Optimizes
Histogram.classicOnly()observations by adding a dedicated classic-only fast path that uses synchronized plain fields instead of the native/hybridLongAdder/DoubleAdderplus buffer path.Fixes #1915
Changes
Histogram.DataPoint.observe()andobserveWithExemplar()through the classic-only fast path whennativeInitialSchema == CLASSIC_HISTOGRAM.Testing
.\mvnw compile -pl prometheus-metrics-core -Dcoverage.skip=true -Dcheckstyle.skip=truegit diff --check