feat: support aggregating metrics across workers in a Node.js worker_…

…threads

CHANGELOG.md

@@ -23,6 +23,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 
 - Support for OpenMetrics and Exemplars
+- Support aggregating metrics across workers in a Node.js `worker_threads`
 
 ## [14.2.0] - 2023-03-06
 

example/cluster-with-worker-threads/index.js

@@ -0,0 +1,27 @@
+'use strict';
+
+const cluster = require('cluster');
+const server = require('./server');
+
+const AggregatorRegistry = require('../..').AggregatorRegistry;
+const aggregatorRegistry = new AggregatorRegistry();
+
+if (cluster.isMaster) {
+	console.log(`Master ${process.pid} is running`);
+
+	for (let i = 0; i < 2; i++) {
+		cluster.fork();
+	}
+
+	cluster.on('exit', worker => {
+		console.log(`worker ${worker.process.pid} died`);
+		console.log("Let's fork another worker!");
+		cluster.fork();
+	});
+} else {
+	server({
+		metrics: {
+			contentType: aggregatorRegistry.contentType,
+		},
+	});
+}

example/cluster-with-worker-threads/server.js

@@ -0,0 +1,40 @@
+'use strict';
+
+const express = require('express');
+const { Counter } = require('../..');
+const AggregatorRegistry = require('../..').AggregatorRegistry;
+const aggregatorRegistry = new AggregatorRegistry();
+const worker = require('./worker');
+const PORT = 3000;
+
+const http_request_total = new Counter({
+	name: 'http_request_total',
+	help: 'request count | clusterId="20212" statusCode="2xx|4xx|5xx"',
+	labelNames: ['clusterId', 'statusCode'],
+});
+
+module.exports = (options = {}) => {
+	const {
+		metrics: { contentType = '' },
+	} = options;
+
+	const app = express();
+
+	app.get('/', async (req, res) => {
+		http_request_total.inc({ clusterId: process.pid, statusCode: 200 });
+		const result = await worker();
+
+		res.send(result);
+	});
+
+	app.get('/metrics', async (req, res) => {
+		const metrics = await aggregatorRegistry.workersMetrics();
+
+		res.set('Content-Type', contentType);
+		res.send(metrics);
+	});
+
+	app.listen(PORT, () => {
+		console.log(`cluster: #${process.pid} - listening on port ${PORT}`);
+	});
+};

example/cluster-with-worker-threads/worker.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const { Counter } = require('../..');
+const {
+	Worker,
+	isMainThread,
+	parentPort,
+	threadId,
+} = require('worker_threads');
+
+if (isMainThread) {
+	module.exports = () =>
+		new Promise((resolve, reject) => {
+			const worker = new Worker(__filename);
+
+			worker.on('message', resolve);
+			worker.on('error', reject);
+		});
+} else {
+	const worker_invocation_total = new Counter({
+		name: 'worker_invocation_total',
+		help: 'worker invocation count | threadId="20212"',
+		labelNames: ['threadId'],
+	});
+
+	worker_invocation_total.inc({ threadId });
+
+	parentPort.postMessage(`result: ${Math.random()}`);
+}

example/cluster/index.js

@@ -0,0 +1,27 @@
+'use strict';
+
+const cluster = require('cluster');
+const server = require('./server');
+
+const AggregatorRegistry = require('../..').AggregatorRegistry;
+const aggregatorRegistry = new AggregatorRegistry();
+
+if (cluster.isMaster) {
+	console.log(`Master ${process.pid} is running`);
+
+	for (let i = 0; i < 2; i++) {
+		cluster.fork();
+	}
+
+	cluster.on('exit', worker => {
+		console.log(`worker ${worker.process.pid} died`);
+		console.log("Let's fork another worker!");
+		cluster.fork();
+	});
+} else {
+	server({
+		metrics: {
+			contentType: aggregatorRegistry.contentType,
+		},
+	});
+}

example/cluster/server.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const express = require('express');
+const { Counter } = require('../..');
+const AggregatorRegistry = require('../..').AggregatorRegistry;
+const aggregatorRegistry = new AggregatorRegistry();
+const PORT = 3000;
+
+const http_request_total = new Counter({
+	name: 'http_request_total',
+	help: 'request count | clusterId="20212" statusCode="2xx|4xx|5xx"',
+	labelNames: ['clusterId', 'statusCode'],
+});
+
+module.exports = (options = {}) => {
+	const {
+		metrics: { contentType = '' },
+	} = options;
+
+	const app = express();
+
+	app.get('/', (req, res) => {
+		http_request_total.inc({ clusterId: process.pid, statusCode: 200 });
+
+		res.send('OK');
+	});
+
+	app.get('/metrics', async (req, res) => {
+		const metrics = await aggregatorRegistry.clusterMetrics();
+
+		res.set('Content-Type', contentType);
+		res.send(metrics);
+	});
+
+	app.listen(PORT, () => {
+		console.log(`cluster: #${process.pid} - listening on port ${PORT}`);
+	});
+};

example/server.js

@@ -1,7 +1,6 @@
 'use strict';
 
 const express = require('express');
-const cluster = require('cluster');
 const server = express();
 const register = require('../').register;
 
@@ -68,13 +67,6 @@ setInterval(() => {
 	g.labels('post', '300').inc();
 }, 100);
 
-if (cluster.isWorker) {
-	// Expose some worker-specific metric as an example
-	setInterval(() => {
-		c.inc({ code: `worker_${cluster.worker.id}` });
-	}, 2000);
-}
-
 const t = [];
 setInterval(() => {
 	for (let i = 0; i < 100; i++) {

example/worker-threads/index.js

@@ -0,0 +1,34 @@
+'use strict';
+
+const express = require('express');
+const { Counter } = require('../..');
+const AggregatorRegistry = require('../..').AggregatorRegistry;
+const aggregatorRegistry = new AggregatorRegistry();
+const worker = require('./worker');
+const PORT = 3000;
+
+const http_request_total = new Counter({
+	name: 'http_request_total',
+	help: 'request count | statusCode="2xx|4xx|5xx"',
+	labelNames: ['statusCode'],
+});
+
+const app = express();
+
+app.get('/', async (req, res) => {
+	http_request_total.inc({ statusCode: 200 });
+	const result = await worker();
+
+	res.send(result);
+});
+
+app.get('/metrics', async (req, res) => {
+	const metrics = await aggregatorRegistry.workersMetrics();
+
+	res.set('Content-Type', aggregatorRegistry.contentType);
+	res.send(metrics);
+});
+
+app.listen(PORT, () => {
+	console.log(`listening on port ${PORT}`);
+});

example/worker-threads/worker.js

@@ -0,0 +1,30 @@
+'use strict';
+
+const { Counter } = require('../..');
+const {
+	Worker,
+	isMainThread,
+	parentPort,
+	threadId,
+} = require('worker_threads');
+
+if (isMainThread) {
+	const worker = new Worker(__filename);
+
+	module.exports.workers = [worker];
+	module.exports.calculate = () =>
+		new Promise((resolve, reject) => {
+			worker.emit('message', resolve);
+			worker.on('error', reject);
+		});
+} else {
+	const worker_invocation_total = new Counter({
+		name: 'worker_invocation_total',
+		help: 'worker invocation count | threadId="20212"',
+		labelNames: ['threadId'],
+	});
+
+	worker_invocation_total.inc({ threadId });
+
+	parentPort.postMessage(`result: ${Math.random()}`);
+}