fix(core): unref timer to not block node exit (#11430)

Add `unref` to make sure that the session flusher or metrics aggregator
does not block nodejs exit. Especially important for serverless
scenarios.

dev-packages/node-integration-tests/suites/metrics/should-exit-forced.js

@@ -0,0 +1,19 @@
+const Sentry = require('@sentry/node');
+
+function configureSentry() {
+  Sentry.init({
+    dsn: 'https://public@dsn.ingest.sentry.io/1337',
+    release: '1.0',
+    autoSessionTracking: false,
+  });
+
+  Sentry.metrics.increment('test');
+}
+
+async function main() {
+  configureSentry();
+  await new Promise(resolve => setTimeout(resolve, 1000));
+  process.exit(0);
+}
+
+main();

dev-packages/node-integration-tests/suites/metrics/should-exit.js

@@ -0,0 +1,18 @@
+const Sentry = require('@sentry/node');
+
+function configureSentry() {
+  Sentry.init({
+    dsn: 'https://public@dsn.ingest.sentry.io/1337',
+    release: '1.0',
+    autoSessionTracking: false,
+  });
+
+  Sentry.metrics.increment('test');
+}
+
+async function main() {
+  configureSentry();
+  await new Promise(resolve => setTimeout(resolve, 1000));
+}
+
+main();

dev-packages/node-integration-tests/suites/metrics/test.ts

@@ -0,0 +1,21 @@
+import { createRunner } from '../../utils/runner';
+
+describe('metrics', () => {
+  test('should exit', done => {
+    const runner = createRunner(__dirname, 'should-exit.js').start();
+
+    setTimeout(() => {
+      expect(runner.childHasExited()).toBe(true);
+      done();
+    }, 5_000);
+  });
+
+  test('should exit forced', done => {
+    const runner = createRunner(__dirname, 'should-exit-forced.js').start();
+
+    setTimeout(() => {
+      expect(runner.childHasExited()).toBe(true);
+      done();
+    }, 5_000);
+  });
+});

dev-packages/node-integration-tests/suites/tracing/metric-summaries/scenario.js

@@ -11,9 +11,6 @@ Sentry.init({
   },
 });
 
-// Stop the process from exiting before the transaction is sent
-setInterval(() => {}, 1000);
-
 Sentry.startSpan(
   {
     name: 'Test Transaction',

packages/core/src/metrics/aggregator.ts

@@ -25,7 +25,9 @@ export class MetricsAggregator implements MetricsAggregatorBase {
   // that we store in memory.
   private _bucketsTotalWeight;
 
-  private readonly _interval: ReturnType<typeof setInterval>;
+  // Cast to any so that it can use Node.js timeout
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  private readonly _interval: any;
 
   // SDKs are required to shift the flush interval by random() * rollup_in_seconds.
   // That shift is determined once per startup to create jittering.
@@ -42,7 +44,13 @@ export class MetricsAggregator implements MetricsAggregatorBase {
   public constructor(private readonly _client: Client<ClientOptions>) {
     this._buckets = new Map();
     this._bucketsTotalWeight = 0;
-    this._interval = setInterval(() => this._flush(), DEFAULT_FLUSH_INTERVAL);
+
+    this._interval = setInterval(() => this._flush(), DEFAULT_FLUSH_INTERVAL) as any;
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+    if (this._interval.unref) {
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+      this._interval.unref();
+    }
     this._flushShift = Math.floor((Math.random() * DEFAULT_FLUSH_INTERVAL) / 1000);
     this._forceFlush = false;
   }

packages/core/src/sessionflusher.ts

@@ -20,7 +20,9 @@ export class SessionFlusher implements SessionFlusherLike {
   public readonly flushTimeout: number;
   private _pendingAggregates: Record<number, AggregationCounts>;
   private _sessionAttrs: ReleaseHealthAttributes;
-  private _intervalId: ReturnType<typeof setInterval>;
+  // Cast to any so that it can use Node.js timeout
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  private _intervalId: any;
   private _isEnabled: boolean;
   private _client: Client;
 
@@ -30,8 +32,13 @@ export class SessionFlusher implements SessionFlusherLike {
     this._pendingAggregates = {};
     this._isEnabled = true;
 
-    // Call to setInterval, so that flush is called every 60 seconds
+    // Call to setInterval, so that flush is called every 60 seconds.
     this._intervalId = setInterval(() => this.flush(), this.flushTimeout * 1000);
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+    if (this._intervalId.unref) {
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+      this._intervalId.unref();
+    }
     this._sessionAttrs = attrs;
   }