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> |
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| .. | ||
| promhttp | ||
| push | ||
| .gitignore | ||
| README.md | ||
| benchmark_test.go | ||
| collector.go | ||
| counter.go | ||
| counter_test.go | ||
| desc.go | ||
| doc.go | ||
| example_clustermanager_test.go | ||
| examples_test.go | ||
| expvar_collector.go | ||
| expvar_collector_test.go | ||
| fnv.go | ||
| gauge.go | ||
| gauge_test.go | ||
| go_collector.go | ||
| go_collector_test.go | ||
| histogram.go | ||
| histogram_test.go | ||
| http.go | ||
| http_test.go | ||
| metric.go | ||
| metric_test.go | ||
| process_collector.go | ||
| process_collector_test.go | ||
| registry.go | ||
| registry_test.go | ||
| summary.go | ||
| summary_test.go | ||
| untyped.go | ||
| value.go | ||
| vec.go | ||
| vec_test.go | ||
README.md
See 
.