fix(sdk-metrics): collect metrics when periodic exporting metric reader flushes

CHANGELOG.md

@@ -23,6 +23,7 @@ For experimental package changes, see the [experimental CHANGELOG](experimental/
     * `telemetry.sdk.language`
     * `telemetry.sdk.version`
 * fix(selenium-tests): updated webpack version for selenium test issue [#3456](https://github.com/open-telemetry/opentelemetry-js/issues/3456) @SaumyaBhushan
+* fix(sdk-metrics): collect metrics when periodic exporting metric reader flushes [#3517](https://github.com/open-telemetry/opentelemetry-js/pull/3517) @legendecas
 * fix(sdk-metrics): fix duplicated registration of metrics for collectors [#3488](https://github.com/open-telemetry/opentelemetry-js/pull/3488) @legendecas
 * fix(core): fix precision loss in numberToHrtime [#3480](https://github.com/open-telemetry/opentelemetry-js/pull/3480) @legendecas
 

packages/sdk-metrics/src/export/PeriodicExportingMetricReader.ts

@@ -90,7 +90,25 @@ export class PeriodicExportingMetricReader extends MetricReader {
   }
 
   private async _runOnce(): Promise<void> {
-    const { resourceMetrics, errors } = await this.collect({});
+    try {
+      await callWithTimeout(this._doRun(), this._exportTimeout);
+    } catch (err) {
+      if (err instanceof TimeoutError) {
+        api.diag.error(
+          'Export took longer than %s milliseconds and timed out.',
+          this._exportTimeout
+        );
+        return;
+      }
+
+      globalErrorHandler(err);
+    }
+  }
+
+  private async _doRun(): Promise<void> {
+    const { resourceMetrics, errors } = await this.collect({
+      timeoutMillis: this._exportTimeout,
+    });
 
     if (errors.length > 0) {
       api.diag.error(
@@ -109,25 +127,15 @@ export class PeriodicExportingMetricReader extends MetricReader {
 
   protected override onInitialized(): void {
     // start running the interval as soon as this reader is initialized and keep handle for shutdown.
-    this._interval = setInterval(async () => {
-      try {
-        await callWithTimeout(this._runOnce(), this._exportTimeout);
-      } catch (err) {
-        if (err instanceof TimeoutError) {
-          api.diag.error(
-            'Export took longer than %s milliseconds and timed out.',
-            this._exportTimeout
-          );
-          return;
-        }
-
-        globalErrorHandler(err);
-      }
+    this._interval = setInterval(() => {
+      // this._runOnce never rejects. Using void operator to suppress @typescript-eslint/no-floating-promises.
+      void this._runOnce();
     }, this._exportInterval);
     unrefTimer(this._interval);
   }
 
   protected async onForceFlush(): Promise<void> {
+    await this._runOnce();
     await this._exporter.forceFlush();
   }
 

packages/sdk-metrics/test/export/PeriodicExportingMetricReader.test.ts

@@ -38,8 +38,9 @@ const MAX_32_BIT_INT = 2 ** 31 - 1;
 class TestMetricExporter implements PushMetricExporter {
   public exportTime = 0;
   public forceFlushTime = 0;
-  public throwException = false;
-  public failureResult = false;
+  public throwExport = false;
+  public throwFlush = false;
+  public rejectExport = false;
   private _batches: ResourceMetrics[] = [];
   private _shutdown: boolean = false;
 
@@ -49,11 +50,11 @@ class TestMetricExporter implements PushMetricExporter {
   ): void {
     this._batches.push(metrics);
 
-    if (this.throwException) {
+    if (this.throwExport) {
       throw new Error('Error during export');
     }
     setTimeout(() => {
-      if (this.failureResult) {
+      if (this.rejectExport) {
         resultCallback({
           code: ExportResultCode.FAILED,
           error: new Error('some error'),
@@ -72,7 +73,7 @@ class TestMetricExporter implements PushMetricExporter {
   }
 
   async forceFlush(): Promise<void> {
-    if (this.throwException) {
+    if (this.throwFlush) {
       throw new Error('Error during forceFlush');
     }
 
@@ -91,6 +92,10 @@ class TestMetricExporter implements PushMetricExporter {
     }
     return this._batches.slice(0, numberOfExports);
   }
+
+  getExports(): ResourceMetrics[] {
+    return this._batches.slice(0);
+  }
 }
 
 class TestDeltaMetricExporter extends TestMetricExporter {
@@ -203,7 +208,7 @@ describe('PeriodicExportingMetricReader', () => {
   describe('periodic export', () => {
     it('should keep running on export errors', async () => {
       const exporter = new TestMetricExporter();
-      exporter.throwException = true;
+      exporter.throwExport = true;
       const reader = new PeriodicExportingMetricReader({
         exporter: exporter,
         exportIntervalMillis: 30,
@@ -218,13 +223,13 @@ describe('PeriodicExportingMetricReader', () => {
         emptyResourceMetrics,
       ]);
 
-      exporter.throwException = false;
+      exporter.throwExport = false;
       await reader.shutdown();
     });
 
     it('should keep running on export failure', async () => {
       const exporter = new TestMetricExporter();
-      exporter.failureResult = true;
+      exporter.rejectExport = true;
       const reader = new PeriodicExportingMetricReader({
         exporter: exporter,
         exportIntervalMillis: 30,
@@ -239,7 +244,7 @@ describe('PeriodicExportingMetricReader', () => {
         emptyResourceMetrics,
       ]);
 
-      exporter.failureResult = false;
+      exporter.rejectExport = false;
       await reader.shutdown();
     });
 
@@ -261,7 +266,7 @@ describe('PeriodicExportingMetricReader', () => {
         emptyResourceMetrics,
       ]);
 
-      exporter.throwException = false;
+      exporter.throwExport = false;
       await reader.shutdown();
     });
   });
@@ -271,7 +276,7 @@ describe('PeriodicExportingMetricReader', () => {
       sinon.restore();
     });
 
-    it('should forceFlush exporter', async () => {
+    it('should collect and forceFlush exporter', async () => {
       const exporter = new TestMetricExporter();
       const exporterMock = sinon.mock(exporter);
       exporterMock.expects('forceFlush').calledOnceWithExactly();
@@ -284,6 +289,10 @@ describe('PeriodicExportingMetricReader', () => {
       reader.setMetricProducer(new TestMetricProducer());
       await reader.forceFlush();
       exporterMock.verify();
+
+      const exports = exporter.getExports();
+      assert.strictEqual(exports.length, 1);
+
       await reader.shutdown();
     });
 
@@ -307,12 +316,13 @@ describe('PeriodicExportingMetricReader', () => {
 
     it('should throw when exporter throws', async () => {
       const exporter = new TestMetricExporter();
-      exporter.throwException = true;
+      exporter.throwFlush = true;
       const reader = new PeriodicExportingMetricReader({
         exporter: exporter,
         exportIntervalMillis: MAX_32_BIT_INT,
         exportTimeoutMillis: 80,
       });
+      reader.setMetricProducer(new TestMetricProducer());
 
       await assertRejects(() => reader.forceFlush(), /Error during forceFlush/);
     });
@@ -454,7 +464,7 @@ describe('PeriodicExportingMetricReader', () => {
 
     it('should throw on non-initialized instance.', async () => {
       const exporter = new TestMetricExporter();
-      exporter.throwException = true;
+      exporter.throwFlush = true;
       const reader = new PeriodicExportingMetricReader({
         exporter: exporter,
         exportIntervalMillis: MAX_32_BIT_INT,