Use lock for Histogram

[utpilla]

Use lock for Histogram updates

Stress Test Results (high contention) with Prometheus Exporter scraping interval = 10s

Multiple threads updating the same Histogram MetricPoint in parallel

C:\opentelemetry-dotnet\test\OpenTelemetry.Tests.Stress.Metrics>dotnet run --framework net6.0 --configuration Release
Running (concurrency = 8, prometheusEndpoint = http://localhost:9184/metrics/), press <Esc> to stop...
2022-08-05T00:18:05.8285320Z Loops: 664,533,915, Loops/Second: 5,193,733, CPU Cycles/Loop: 3,124, RunwayTime (Seconds): 121
2022-08-05T00:18:06.0325689Z Loops: 665,604,237, Loops/Second: 5,170,911, CPU Cycles/Loop: 3,104, RunwayTime (Seconds): 121
2022-08-05T00:18:06.2391271Z Loops: 666,664,950, Loops/Second: 5,129,816, CPU Cycles/Loop: 3,126, RunwayTime (Seconds): 121
2022-08-05T00:18:06.4450077Z Loops: 667,725,432, Loops/Second: 5,185,127, CPU Cycles/Loop: 3,106, RunwayTime (Seconds): 121
2022-08-05T00:18:06.6519226Z Loops: 668,790,473, Loops/Second: 5,139,500, CPU Cycles/Loop: 3,074, RunwayTime (Seconds): 122
2022-08-05T00:18:06.8585657Z Loops: 669,851,220, Loops/Second: 5,144,074, CPU Cycles/Loop: 3,169, RunwayTime (Seconds): 122

Stress Test Results (low contention) with Prometheus Exporter scraping interval = 10s

Multiple threads updating random Histogram MetricPoints in parallel

C:\opentelemetry-dotnet\test\OpenTelemetry.Tests.Stress.Metrics>dotnet run --framework net6.0 --configuration Release
Running (concurrency = 8, prometheusEndpoint = http://localhost:9184/metrics/), press <Esc> to stop...
2022-08-04T23:02:23.9567130Z Loops: 2,429,503,031, Loops/Second: 20,119,653, CPU Cycles/Loop: 1,128, RunwayTime (Seconds): 120
2022-08-04T23:02:24.2277354Z Loops: 2,434,415,612, Loops/Second: 19,988,132, CPU Cycles/Loop: 1,130, RunwayTime (Seconds): 121
2022-08-04T23:02:24.4725452Z Loops: 2,439,784,407, Loops/Second: 19,949,797, CPU Cycles/Loop: 1,128, RunwayTime (Seconds): 121
2022-08-04T23:02:24.7065189Z Loops: 2,444,642,611, Loops/Second: 20,134,782, CPU Cycles/Loop: 1,129, RunwayTime (Seconds): 121
2022-08-04T23:02:24.9475497Z Loops: 2,449,492,448, Loops/Second: 19,901,301, CPU Cycles/Loop: 1,130, RunwayTime (Seconds): 121
2022-08-04T23:02:25.1765231Z Loops: 2,453,822,909, Loops/Second: 19,435,860, CPU Cycles/Loop: 1,119, RunwayTime (Seconds): 122

Benchmark Results

// * Summary *

BenchmarkDotNet=v0.13.1, OS=Windows 10.0.22000
Intel Core i7-9700 CPU 3.00GHz, 1 CPU, 8 logical and 8 physical cores
.NET SDK=6.0.302
[Host] : .NET 6.0.7 (6.0.722.32202), X64 RyuJIT
DefaultJob : .NET 6.0.7 (6.0.722.32202), X64 RyuJIT

Method	BoundCount	Mean	Error	StdDev
HistogramHotPath	10	46.44 ns	0.842 ns	0.746 ns
HistogramWith1LabelHotPath	10	97.67 ns	1.968 ns	3.447 ns
HistogramWith3LabelsHotPath	10	202.86 ns	4.035 ns	4.956 ns
HistogramWith5LabelsHotPath	10	292.78 ns	5.758 ns	7.282 ns
HistogramWith7LabelsHotPath	10	355.86 ns	7.033 ns	14.366 ns
HistogramHotPath	20	49.53 ns	1.006 ns	0.941 ns
HistogramWith1LabelHotPath	20	106.52 ns	2.099 ns	2.943 ns
HistogramWith3LabelsHotPath	20	207.65 ns	4.064 ns	5.139 ns
HistogramWith5LabelsHotPath	20	299.79 ns	5.967 ns	9.465 ns
HistogramWith7LabelsHotPath	20	358.21 ns	7.190 ns	14.023 ns
HistogramHotPath	50	59.17 ns	1.210 ns	2.055 ns
HistogramWith1LabelHotPath	50	115.68 ns	2.265 ns	3.023 ns
HistogramWith3LabelsHotPath	50	221.92 ns	4.318 ns	4.973 ns
HistogramWith5LabelsHotPath	50	310.69 ns	6.006 ns	11.571 ns
HistogramWith7LabelsHotPath	50	378.06 ns	7.383 ns	8.789 ns
HistogramHotPath	100	75.17 ns	1.533 ns	3.701 ns
HistogramWith1LabelHotPath	100	127.82 ns	2.528 ns	3.105 ns
HistogramWith3LabelsHotPath	100	235.38 ns	4.545 ns	10.258 ns
HistogramWith5LabelsHotPath	100	328.82 ns	6.550 ns	13.817 ns
HistogramWith7LabelsHotPath	100	393.21 ns	7.738 ns	10.592 ns

[utpilla]

Ignore this file.

[codecov]

Codecov Report

Merging #3547 (f44920c) into main (666a0c1) will increase coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3547      +/-   ##
==========================================
+ Coverage   87.04%   87.17%   +0.13%     
==========================================
  Files         275      275              
  Lines        9959     9951       -8     
==========================================
+ Hits         8669     8675       +6     
+ Misses       1290     1276      -14     

Impacted Files	Coverage Δ
src/OpenTelemetry/Metrics/HistogramBuckets.cs	100.00% <ø> (ø)
src/OpenTelemetry/Metrics/MetricPoint.cs	85.60% <100.00%> (+0.60%)	⬆️
src/OpenTelemetry/ProviderExtensions.cs	81.81% <0.00%> (-9.10%)	⬇️
...Telemetry/Metrics/PeriodicExportingMetricReader.cs	72.72% <0.00%> (-5.46%)	⬇️
...tpListener/Internal/PrometheusCollectionManager.cs	80.48% <0.00%> (+2.43%)	⬆️
...metryProtocol/Implementation/ActivityExtensions.cs	94.50% <0.00%> (+3.29%)	⬆️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	77.27% <0.00%> (+18.18%)	⬆️
...entation/ExportClient/OtlpGrpcTraceExportClient.cs	78.57% <0.00%> (+28.57%)	⬆️

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