feat: added ability to disable worker thread tracing (#2131)

Controlled via INSTANA_DISABLE_WORKER_THREADS environment variable.
Use case:
Disable tracing for worker threads not part of the customer application.
Workers spawned by dependencies (e.g., pino) are no longer monitored.

refs https://jsw.ibm.com/browse/INSTA-62583

Author: aryamohanan

packages/collector/src/index.js

@@ -41,6 +41,25 @@ try {
   // Worker threads are not available, so we know that this is the main thread.
 }
 
+// Check if worker threads should be disabled via environment variable.
+// Disabling worker threads may be necessary in environments where
+// multi-threading causes issues or monitoring of worker threads is not required.
+const disableWorkerThreads = process.env.INSTANA_DISABLE_WORKER_THREADS?.toLowerCase() === 'true';
+
+if (disableWorkerThreads && !isMainThread) {
+  // eslint-disable-next-line no-console
+  console.warn(
+    'Worker threads are disabled via INSTANA_DISABLE_WORKER_THREADS. ' +
+      'This worker thread will not be monitored by Instana.'
+  );
+
+  module.exports = function noOp() {};
+  module.exports.default = function noOp() {};
+
+  // @ts-ignore
+  return;
+}
+
 const path = require('path');
 const instanaNodeJsCore = require('@instana/core');
 const instanaSharedMetrics = require('@instana/shared-metrics');

packages/collector/test/tracing/logging/pino/app.js

@@ -14,7 +14,10 @@ process.on('SIGTERM', () => {
 });
 
 require('./mockVersion');
-require('../../../..')();
+
+if (!process.env.NODE_OPTIONS || !process.env.NODE_OPTIONS.includes('src/immediate')) {
+  require('../../../..')();
+}
 
 const fetch = require('node-fetch-v2');
 const bodyParser = require('body-parser');
@@ -212,6 +215,22 @@ app.get('/express-pino-error-random-object-and-string', (req, res) => {
   finish(res);
 });
 
+app.get('/thread-stream-test', (req, res) => {
+  try {
+    const mode = process.env.PINO_WORKER_MODE || 'transport';
+
+    const logger =
+      mode === 'transport'
+        ? pino({ transport: { target: 'pino-pretty', options: { destination: 1 } } })
+        : pino({ destination: 1 });
+    logger.error('Pino worker test error log');
+
+    res.sendStatus(200);
+  } catch (e) {
+    res.status(500).send(`Failed: ${e.message}`);
+  }
+});
+
 function finish(res) {
   fetch(`http://127.0.0.1:${agentPort}`).then(() => {
     res.sendStatus(200);

packages/collector/test/tracing/logging/pino/test.js

@@ -102,6 +102,52 @@ describe('tracing/logging/pino', function () {
       });
     });
   });
+  describe('pino thread-stream worker', function () {
+    let controls;
+
+    before(async () => {
+      controls = new ProcessControls({
+        dirname: __dirname,
+        useGlobalAgent: true,
+        env: {
+          PINO_WORKER_MODE: 'transport',
+          PINO_EXPRESS: 'false',
+          NODE_OPTIONS: `--require ${path.join(__dirname, '../../../..', 'src', 'immediate.js')}`,
+          INSTANA_DISABLE_WORKER_THREADS: 'true'
+        }
+      });
+
+      await controls.startAndWaitForAgentConnection();
+    });
+
+    beforeEach(async () => {
+      await agentControls.clearReceivedTraceData();
+    });
+
+    after(async () => {
+      await controls.stop();
+    });
+
+    it('must trace without errors', async () => {
+      await controls.sendRequest({
+        method: 'GET',
+        path: '/thread-stream-test'
+      });
+      await testUtils.delay(1000);
+      const spans = await agentControls.getSpans();
+
+      const logSpan = spans.find(s => s.n === 'log.pino');
+      expect(logSpan).to.exist;
+      expect(logSpan.data.log.message).to.equal('Pino worker test error log');
+
+      const httpSpan = spans.find(s => s.n === 'node.http.server');
+      expect(httpSpan).to.exist;
+      expect(httpSpan.data.http.path_tpl).to.equal('/thread-stream-test');
+      expect(httpSpan.data.http.status).to.equal(200);
+
+      expect(spans).to.have.lengthOf(2);
+    });
+  });
 
   function runTests(pinoVersion, useExpressPino) {
     const suffix = useExpressPino ? ' (express-pino)' : '';