Lock-free updates for HistogramSumCount (#2961)

open-telemetry · Mar 4, 2022 · af0c9b4 · af0c9b4
1 parent cee9006
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diff --git a/src/OpenTelemetry/CHANGELOG.md b/src/OpenTelemetry/CHANGELOG.md
@@ -6,8 +6,10 @@
   ([#2949](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2949/)
   [#2897](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2897))
 
-* Perf improvement for Histogram, by implementing lock-free updates.
-  ([#2951](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2951))
+* Perf improvement for Histogram and HistogramSumCount by implementing lock-free
+  updates.
+  ([2951](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2951))
+  ([2961](https://github.com/open-telemetry/opentelemetry-dotnet/pull/2961))
 
 ## 1.2.0-rc2
 

diff --git a/src/OpenTelemetry/Metrics/MetricPoint.cs b/src/OpenTelemetry/Metrics/MetricPoint.cs
@@ -347,10 +347,22 @@ internal void Update(double number)
 
                 case AggregationType.HistogramSumCount:
                     {
-                        lock (this.histogramBuckets.LockObject)
+                        var sw = default(SpinWait);
+                        while (true)
                         {
-                            this.runningValue.AsLong++;
-                            this.histogramBuckets.RunningSum += number;
+                            if (Interlocked.Exchange(ref this.histogramBuckets.IsCriticalSectionOccupied, 1) == 0)
+                            {
+                                unchecked
+                                {
+                                    this.runningValue.AsLong++;
+                                    this.histogramBuckets.RunningSum += number;
+                                }
+
+                                this.histogramBuckets.IsCriticalSectionOccupied = 0;
+                                break;
+                            }
+
+                            sw.SpinOnce();
                         }
 
                         break;