Remove useless event listener when outside of cluster mode

siimon · Jul 31, 2021 · bfeabc2 · bfeabc2
1 parent c7b9a9d
commit bfeabc2
Show file tree

Hide file tree

Showing 2 changed files with 38 additions and 21 deletions.
diff --git a/lib/cluster.js b/lib/cluster.js
@@ -180,27 +180,29 @@ function addListeners() {
 			}
 		});
 	}
-}
 
-// Respond to master's requests for worker's local metrics.
-process.on('message', message => {
-	if (cluster().isWorker && message.type === GET_METRICS_REQ) {
-		Promise.all(registries.map(r => r.getMetricsAsJSON()))
-			.then(metrics => {
-				process.send({
-					type: GET_METRICS_RES,
-					requestId: message.requestId,
-					metrics,
-				});
-			})
-			.catch(error => {
-				process.send({
-					type: GET_METRICS_RES,
-					requestId: message.requestId,
-					error: error.message,
-				});
-			});
+	if (cluster().isWorker) {
+		// Respond to master's requests for worker's local metrics.
+		process.on('message', message => {
+			if (message.type === GET_METRICS_REQ) {
+				Promise.all(registries.map(r => r.getMetricsAsJSON()))
+					.then(metrics => {
+						process.send({
+							type: GET_METRICS_RES,
+							requestId: message.requestId,
+							metrics,
+						});
+					})
+					.catch(error => {
+						process.send({
+							type: GET_METRICS_RES,
+							requestId: message.requestId,
+							error: error.message,
+						});
+					});
+			}
+		});
 	}
-});
+}
 
 module.exports = AggregatorRegistry;
diff --git a/test/clusterTest.js b/test/clusterTest.js
@@ -1,9 +1,10 @@
 'use strict';
 
 const cluster = require('cluster');
+const process = require('process');
 
 describe('AggregatorRegistry', () => {
-	it('requiring the cluster should not add any listeners', () => {
+	it('requiring the cluster should not add any listeners on the cluster module', () => {
 		const originalListenerCount = cluster.listenerCount('message');
 
 		require('../lib/cluster');
@@ -17,6 +18,20 @@ describe('AggregatorRegistry', () => {
 		expect(cluster.listenerCount('message')).toBe(originalListenerCount);
 	});
 
+	it('requiring the cluster should not add any listeners on the process module', () => {
+		const originalListenerCount = process.listenerCount('message');
+
+		require('../lib/cluster');
+
+		expect(process.listenerCount('message')).toBe(originalListenerCount);
+
+		jest.resetModules();
+
+		require('../lib/cluster');
+
+		expect(process.listenerCount('message')).toBe(originalListenerCount);
+	});
+
 	describe('aggregatorRegistry.clusterMetrics()', () => {
 		it('works properly if there are no cluster workers', async () => {
 			const AggregatorRegistry = require('../lib/cluster');