3cf50db5fd
While hash collisions are quite rare, the current state of the client library carries a risk of merging two separate label values into a single metric bucket. The effects are near impossible to detect and the result will be missing or incorrect counters. This changeset handles hash collisions by falling back to collision resolution if multiple label values hash to the same value. This works similar to separate chaining using a slice. Extra storage is minimized to only the value key slice to that metrics can be differentiated within a bucket. In general, the cost of handling collisions is completely minimized under normal operation. Performance does show slight increases in certain areas, but these are more likely statistically anomalies. More importantly, zero allocation behavior for metrics is preserved on the fast path. Minimal allocations may be made during collision handling but this has minimal effect. Benchmark comparisons with and without collision resolution follow. ``` benchmark old ns/op new ns/op delta BenchmarkCounterWithLabelValues-4 99.0 107 +8.08% BenchmarkCounterWithLabelValuesConcurrent-4 79.6 91.0 +14.32% BenchmarkCounterWithMappedLabels-4 518 542 +4.63% BenchmarkCounterWithPreparedMappedLabels-4 127 137 +7.87% BenchmarkCounterNoLabels-4 19.5 19.1 -2.05% BenchmarkGaugeWithLabelValues-4 97.4 110 +12.94% BenchmarkGaugeNoLabels-4 12.4 10.3 -16.94% BenchmarkSummaryWithLabelValues-4 1204 915 -24.00% BenchmarkSummaryNoLabels-4 936 847 -9.51% BenchmarkHistogramWithLabelValues-4 147 147 +0.00% BenchmarkHistogramNoLabels-4 50.6 49.3 -2.57% BenchmarkHistogramObserve1-4 37.9 37.5 -1.06% BenchmarkHistogramObserve2-4 122 137 +12.30% BenchmarkHistogramObserve4-4 310 352 +13.55% BenchmarkHistogramObserve8-4 691 729 +5.50% BenchmarkHistogramWrite1-4 3374 3097 -8.21% BenchmarkHistogramWrite2-4 5310 5051 -4.88% BenchmarkHistogramWrite4-4 12094 10690 -11.61% BenchmarkHistogramWrite8-4 19416 17755 -8.55% BenchmarkHandler-4 11934304 13765894 +15.35% BenchmarkSummaryObserve1-4 1119 1105 -1.25% BenchmarkSummaryObserve2-4 3679 3430 -6.77% BenchmarkSummaryObserve4-4 10678 7982 -25.25% BenchmarkSummaryObserve8-4 22974 16689 -27.36% BenchmarkSummaryWrite1-4 25962 14680 -43.46% BenchmarkSummaryWrite2-4 38019 35073 -7.75% BenchmarkSummaryWrite4-4 78027 56816 -27.18% BenchmarkSummaryWrite8-4 117220 132248 +12.82% BenchmarkMetricVecWithLabelValuesBasic-4 138 133 -3.62% BenchmarkMetricVecWithLabelValues2Keys10ValueCardinality-4 150 144 -4.00% BenchmarkMetricVecWithLabelValues4Keys10ValueCardinality-4 263 256 -2.66% BenchmarkMetricVecWithLabelValues2Keys100ValueCardinality-4 145 155 +6.90% BenchmarkMetricVecWithLabelValues10Keys100ValueCardinality-4 606 634 +4.62% BenchmarkMetricVecWithLabelValues10Keys1000ValueCardinality-4 746 641 -14.08% benchmark old allocs new allocs delta BenchmarkCounterWithLabelValues-4 0 0 +0.00% BenchmarkCounterWithLabelValuesConcurrent-4 0 0 +0.00% BenchmarkCounterWithMappedLabels-4 2 2 +0.00% BenchmarkCounterWithPreparedMappedLabels-4 0 0 +0.00% BenchmarkCounterNoLabels-4 0 0 +0.00% BenchmarkGaugeWithLabelValues-4 0 0 +0.00% BenchmarkGaugeNoLabels-4 0 0 +0.00% BenchmarkSummaryWithLabelValues-4 0 0 +0.00% BenchmarkSummaryNoLabels-4 0 0 +0.00% BenchmarkHistogramWithLabelValues-4 0 0 +0.00% BenchmarkHistogramNoLabels-4 0 0 +0.00% BenchmarkMetricVecWithLabelValuesBasic-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues2Keys10ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues4Keys10ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues2Keys100ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues10Keys100ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues10Keys1000ValueCardinality-4 0 0 +0.00% benchmark old bytes new bytes delta BenchmarkCounterWithLabelValues-4 0 0 +0.00% BenchmarkCounterWithLabelValuesConcurrent-4 0 0 +0.00% BenchmarkCounterWithMappedLabels-4 336 336 +0.00% BenchmarkCounterWithPreparedMappedLabels-4 0 0 +0.00% BenchmarkCounterNoLabels-4 0 0 +0.00% BenchmarkGaugeWithLabelValues-4 0 0 +0.00% BenchmarkGaugeNoLabels-4 0 0 +0.00% BenchmarkSummaryWithLabelValues-4 0 0 +0.00% BenchmarkSummaryNoLabels-4 0 0 +0.00% BenchmarkHistogramWithLabelValues-4 0 0 +0.00% BenchmarkHistogramNoLabels-4 0 0 +0.00% BenchmarkMetricVecWithLabelValuesBasic-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues2Keys10ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues4Keys10ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues2Keys100ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues10Keys100ValueCardinality-4 0 0 +0.00% BenchmarkMetricVecWithLabelValues10Keys1000ValueCardinality-4 0 0 +0.00% ``` Signed-off-by: Stephen J Day <stephen.day@docker.com> |
||
|---|---|---|
| api/prometheus | ||
| examples | ||
| prometheus | ||
| .gitignore | ||
| .travis.yml | ||
| AUTHORS.md | ||
| CHANGELOG.md | ||
| CONTRIBUTING.md | ||
| LICENSE | ||
| NOTICE | ||
| README.md | ||
| VERSION | ||
README.md
Prometheus Go client library
This is the Go client library for Prometheus. It has two separate parts, one for instrumenting application code, and one for creating clients that talk to the Prometheus HTTP API.
Instrumenting applications
The
prometheus directory
contains the instrumentation library. See the
best practices section of the
Prometheus documentation to learn more about instrumenting applications.
The
examples directory
contains simple examples of instrumented code.
Client for the Prometheus HTTP API
The
api/prometheus directory
contains the client for the
Prometheus HTTP API. It allows you
to write Go applications that query time series data from a Prometheus server.
Where is model, extraction, and text?
The model packages has been moved to
prometheus/common/model.
The extraction and text packages are now contained in
prometheus/common/expfmt.
Contributing and community
See the contributing guidelines and the Community section of the homepage.