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

Author: AbhiPrasad

packages/core/src/metrics/aggregator.ts

@@ -37,7 +37,7 @@ export class MetricsAggregator implements MetricsAggregatorBase {
   public constructor(private readonly _client: Client) {
     this._buckets = new Map();
     this._bucketsTotalWeight = 0;
-    this._interval = setInterval(() => this._flush(), DEFAULT_FLUSH_INTERVAL);
+    this._interval = setInterval(() => this._flush(), DEFAULT_FLUSH_INTERVAL).unref();
     this._flushShift = Math.floor((Math.random() * DEFAULT_FLUSH_INTERVAL) / 1000);
     this._forceFlush = false;
   }

packages/core/src/sessionflusher.ts

@@ -30,8 +30,8 @@ export class SessionFlusher implements SessionFlusherLike {
     this._pendingAggregates = {};
     this._isEnabled = true;
 
-    // Call to setInterval, so that flush is called every 60 seconds
-    this._intervalId = setInterval(() => this.flush(), this.flushTimeout * 1000);
+    // Call to setInterval, so that flush is called every 60 seconds.
+    this._intervalId = setInterval(() => this.flush(), this.flushTimeout * 1000).unref();
     this._sessionAttrs = attrs;
   }