fix(sdk-metrics): prevent per-reader storages from keeping unreported accumulations in memory

CHANGELOG.md

@@ -15,6 +15,8 @@ For experimental package changes, see the [experimental CHANGELOG](experimental/
 
 * fix(sdk-trace-base): BatchSpanProcessor flushes when `maxExportBatchSize` is reached [#3958](https://github.com/open-telemetry/opentelemetry-js/pull/3958) @nordfjord
 * fix(sdk-metrics): allow instrument names to contain '/' [#4155](https://github.com/open-telemetry/opentelemetry-js/pull/4155)
+* fix(sdk-metrics): prevent per-reader storages from keeping unreported accumulations in memory [#4163](https://github.com/open-telemetry/opentelemetry-js/pull/4163) @pichlermarc
+  * fixes a memory leak which occurred when two or more `MetricReader` instances are registered to a `MeterProvider`
 * fix(sdk-metrics): do not report empty scopes and metrics [#4135](https://github.com/open-telemetry/opentelemetry-js/pull/4135) @pichlermarc
   * Instruments that were created, but did not have measurements will not be exported anymore
   * Meters (Scopes) that were created, but did not have any instruments with measurements under them will not be exported anymore.

packages/sdk-metrics/src/state/AsyncMetricStorage.ts

@@ -42,11 +42,15 @@ export class AsyncMetricStorage<T extends Maybe<Accumulation>>
   constructor(
     _instrumentDescriptor: InstrumentDescriptor,
     aggregator: Aggregator<T>,
-    private _attributesProcessor: AttributesProcessor
+    private _attributesProcessor: AttributesProcessor,
+    collectorHandles: MetricCollectorHandle[]
   ) {
     super(_instrumentDescriptor);
     this._deltaMetricStorage = new DeltaMetricProcessor(aggregator);
-    this._temporalMetricStorage = new TemporalMetricProcessor(aggregator);
+    this._temporalMetricStorage = new TemporalMetricProcessor(
+      aggregator,
+      collectorHandles
+    );
   }
 
   record(measurements: AttributeHashMap<number>, observationTime: HrTime) {
@@ -66,14 +70,12 @@ export class AsyncMetricStorage<T extends Maybe<Accumulation>>
    */
   collect(
     collector: MetricCollectorHandle,
-    collectors: MetricCollectorHandle[],
     collectionTime: HrTime
   ): Maybe<MetricData> {
     const accumulations = this._deltaMetricStorage.collect();
 
     return this._temporalMetricStorage.buildMetrics(
       collector,
-      collectors,
       this._instrumentDescriptor,
       accumulations,
       collectionTime

packages/sdk-metrics/src/state/MeterSharedState.ts

@@ -96,11 +96,7 @@ export class MeterSharedState {
 
     const metricDataList = storages
       .map(metricStorage => {
-        return metricStorage.collect(
-          collector,
-          this._meterProviderSharedState.metricCollectors,
-          collectionTime
-        );
+        return metricStorage.collect(collector, collectionTime);
       })
       .filter(isNotNullish);
 
@@ -145,7 +141,8 @@ export class MeterSharedState {
       const viewStorage = new MetricStorageType(
         viewDescriptor,
         aggregator,
-        view.attributesProcessor
+        view.attributesProcessor,
+        this._meterProviderSharedState.metricCollectors
       ) as R;
       this.metricStorageRegistry.register(viewStorage);
       return viewStorage;
@@ -169,7 +166,8 @@ export class MeterSharedState {
           const storage = new MetricStorageType(
             descriptor,
             aggregator,
-            AttributesProcessor.Noop()
+            AttributesProcessor.Noop(),
+            [collector]
           ) as R;
           this.metricStorageRegistry.registerForCollector(collector, storage);
           return storage;
@@ -191,6 +189,7 @@ interface MetricStorageConstructor {
   new (
     instrumentDescriptor: InstrumentDescriptor,
     aggregator: Aggregator<Maybe<Accumulation>>,
-    attributesProcessor: AttributesProcessor
+    attributesProcessor: AttributesProcessor,
+    collectors: MetricCollectorHandle[]
   ): MetricStorage;
 }

packages/sdk-metrics/src/state/MetricStorage.ts

@@ -39,7 +39,6 @@ export abstract class MetricStorage {
    */
   abstract collect(
     collector: MetricCollectorHandle,
-    collectors: MetricCollectorHandle[],
     collectionTime: HrTime
   ): Maybe<MetricData>;
 

packages/sdk-metrics/src/state/SyncMetricStorage.ts

@@ -41,11 +41,15 @@ export class SyncMetricStorage<T extends Maybe<Accumulation>>
   constructor(
     instrumentDescriptor: InstrumentDescriptor,
     aggregator: Aggregator<T>,
-    private _attributesProcessor: AttributesProcessor
+    private _attributesProcessor: AttributesProcessor,
+    collectorHandles: MetricCollectorHandle[]
   ) {
     super(instrumentDescriptor);
     this._deltaMetricStorage = new DeltaMetricProcessor(aggregator);
-    this._temporalMetricStorage = new TemporalMetricProcessor(aggregator);
+    this._temporalMetricStorage = new TemporalMetricProcessor(
+      aggregator,
+      collectorHandles
+    );
   }
 
   record(
@@ -66,14 +70,12 @@ export class SyncMetricStorage<T extends Maybe<Accumulation>>
    */
   collect(
     collector: MetricCollectorHandle,
-    collectors: MetricCollectorHandle[],
     collectionTime: HrTime
   ): Maybe<MetricData> {
     const accumulations = this._deltaMetricStorage.collect();
 
     return this._temporalMetricStorage.buildMetrics(
       collector,
-      collectors,
       this._instrumentDescriptor,
       accumulations,
       collectionTime

packages/sdk-metrics/src/state/TemporalMetricProcessor.ts

@@ -61,7 +61,14 @@ export class TemporalMetricProcessor<T extends Maybe<Accumulation>> {
     LastReportedHistory<T>
   >();
 
-  constructor(private _aggregator: Aggregator<T>) {}
+  constructor(
+    private _aggregator: Aggregator<T>,
+    collectorHandles: MetricCollectorHandle[]
+  ) {
+    collectorHandles.forEach(handle => {
+      this._unreportedAccumulations.set(handle, []);
+    });
+  }
 
   /**
    * Builds the {@link MetricData} streams to report against a specific MetricCollector.
@@ -74,12 +81,11 @@ export class TemporalMetricProcessor<T extends Maybe<Accumulation>> {
    */
   buildMetrics(
     collector: MetricCollectorHandle,
-    collectors: MetricCollectorHandle[],
     instrumentDescriptor: InstrumentDescriptor,
     currentAccumulations: AttributeHashMap<T>,
     collectionTime: HrTime
   ): Maybe<MetricData> {
-    this._stashAccumulations(collectors, currentAccumulations);
+    this._stashAccumulations(currentAccumulations);
     const unreportedAccumulations =
       this._getMergedUnreportedAccumulations(collector);
 
@@ -148,18 +154,16 @@ export class TemporalMetricProcessor<T extends Maybe<Accumulation>> {
     );
   }
 
-  private _stashAccumulations(
-    collectors: MetricCollectorHandle[],
-    currentAccumulation: AttributeHashMap<T>
-  ) {
-    collectors.forEach(it => {
-      let stash = this._unreportedAccumulations.get(it);
+  private _stashAccumulations(currentAccumulation: AttributeHashMap<T>) {
+    const registeredCollectors = this._unreportedAccumulations.keys();
+    for (const collector of registeredCollectors) {
+      let stash = this._unreportedAccumulations.get(collector);
       if (stash === undefined) {
         stash = [];
-        this._unreportedAccumulations.set(it, stash);
+        this._unreportedAccumulations.set(collector, stash);
       }
       stash.push(currentAccumulation);
-    });
+    }
   }
 
   private _getMergedUnreportedAccumulations(collector: MetricCollectorHandle) {