Fix memory leak: clean up listeners on repeated useAzureMonitor calls

.github/workflows/integration.yml

@@ -13,13 +13,13 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [18.x]
+        node-version: [20.x]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - run: openssl req -x509 -nodes -newkey rsa -keyout ./test/certs/server-key.pem -out ./test/certs/server-cert.pem -days 1 -subj "/C=CL/ST=RM/L=OpenTelemetryTest/O=Root/OU=Test/CN=ca"
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v4
       with:
         node-version: ${{ matrix.node-version }}
     - run: npm i

.github/workflows/node.js-linux-arm64.yml

@@ -8,43 +8,27 @@ on:
 
 jobs:
   build:
-    # Use a standard Ubuntu runner instead of requesting ARM64 hardware directly
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04-arm
 
     strategy:
       matrix:
-        # Using the same Node versions as the main workflow
-        node-version: [18, 20, 22, 24]
+        node-version: [20.x, 22.x, 24.x]
 
     steps:
-      - name: Checkout code
-        uses: actions/checkout@v3
-
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v2
-        with:
-          platforms: arm64
-
-      - name: Run tests in ARM64 Docker container
+      - uses: actions/checkout@v4
+
+      - name: Generate SSL Certificate
         run: |
-          # Generate SSL certificates first (outside container)
           mkdir -p ./test/certs
           openssl req -x509 -nodes -newkey rsa:2048 -keyout ./test/certs/server-key.pem -out ./test/certs/server-cert.pem -days 1 -subj "/C=CL/ST=RM/L=OpenTelemetryTest/O=Root/OU=Test/CN=ca"
-
-          # Set proper permissions for the mounted volume
-          chmod -R 777 .
-
-          # Run the Node.js tests in ARM64 container
-          docker run --rm -v ${{ github.workspace }}:/app -w /app --platform linux/arm64 node:${{ matrix.node-version }}-alpine sh -c '
-            # Install build tools needed for native modules
-            apk add --no-cache python3 make g++ 
-
-            # Clean out directory only (preserve node_modules for fresh install)
-            rm -rf ./out
-
-            # Install dependencies and run tests
-            npm i
-            npm run build --if-present
-            npm run lint
-            npm test
-          '
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - run: npm run clean
+      - run: npm i
+      - run: npm run build --if-present
+      - run: npm run lint
+      - run: npm test

.github/workflows/node.js-windows-arm64.yml

@@ -1,56 +1,26 @@
 name: Node.js CI (Windows ARM64)
 
+# NOTE: GitHub does not offer public Windows ARM64 runners.
+# The previous version of this workflow used QEMU to emulate ARM64 Linux in
+# Docker, which was neither testing Windows nor reliably passing due to
+# emulation flakiness.  Native ARM64 testing is now covered by the
+# node.js-linux-arm64.yml workflow using ubuntu-24.04-arm runners.
+#
+# This workflow will be enabled once GitHub provides public Windows ARM64
+# runners (or a self-hosted runner is configured).
+
 on:
   push:
     branches: [ main ]
   pull_request:
     branches: [ main ]
 
 jobs:
-  build:
-    # Use the Linux runner instead as it has better Docker support
+  placeholder:
     runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        # Using the same Node versions as the main workflow but without the .x suffix for Docker images
-        node-version: [18, 20, 22, 24]
-
     steps:
-    - name: Checkout code
-      uses: actions/checkout@v3
-
-    - name: Set up QEMU
-      uses: docker/setup-qemu-action@v2
-      with:
-        platforms: arm64
-      # Generate certificates using Linux openssl command
-    - name: Generate SSL Certificate
-      run: |
-        # Create certificates directory
-        mkdir -p ./test/certs
-
-        # Generate SSL certificates
-        openssl req -x509 -nodes -newkey rsa:2048 -keyout ./test/certs/server-key.pem -out ./test/certs/server-cert.pem -days 1 -subj "/C=CL/ST=RM/L=OpenTelemetryTest/O=Root/OU=Test/CN=ca"
-
-        # Set permissions
-        chmod -R 777 .
-
-    - name: Run Node.js ${{ matrix.node-version }} tests in ARM64 Docker container
-      run: |
-        # Run the tests in an ARM64 container
-        docker run --rm -v ${{ github.workspace }}:/app -w /app --platform linux/arm64 node:${{ matrix.node-version }}-alpine sh -c '
-          echo "Running tests for Node.js ${{ matrix.node-version }} on ARM64 emulation (Windows-targeted tests)"
-
-          # Install build dependencies for native modules
-          apk add --no-cache python3 make g++
-
-          # Clean out directory only (preserve node_modules for fresh install)
-          rm -rf ./out
-
-          # Install dependencies and run tests
-          npm i
-          npm run build --if-present
-          npm run lint
-          npm test
-        '
+      - name: Windows ARM64 testing not yet available
+        run: |
+          echo "Skipped: GitHub does not offer public Windows ARM64 runners."
+          echo "ARM64 testing is covered by the Linux ARM64 workflow (ubuntu-24.04-arm)."
+          echo "See: https://github.com/actions/runner-images#available-images"

.github/workflows/node.js-windows.yml

@@ -0,0 +1,56 @@
+name: Node.js CI (Windows)
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+
+    runs-on: windows-latest
+
+    strategy:
+      matrix:
+        node-version: [20.x, 22.x, 24.x]
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Generate SSL Certificate
+      shell: pwsh
+      run: |
+        $certsDir = ".\test\certs"
+        if (-not (Test-Path $certsDir)) {
+          New-Item -ItemType Directory -Path $certsDir
+        }
+
+        $cert = New-SelfSignedCertificate -Subject "CN=ca,OU=Test,O=Root,L=OpenTelemetryTest,ST=RM,C=CL" -NotAfter (Get-Date).AddDays(1)
+
+        # Export certificate to PEM format
+        $certBytes = $cert.Export("Cert")
+        $pemCert = "-----BEGIN CERTIFICATE-----`r`n" + [Convert]::ToBase64String($certBytes, [System.Base64FormattingOptions]::InsertLineBreaks) + "`r`n-----END CERTIFICATE-----"
+        Set-Content -Path "$certsDir\server-cert.pem" -Value $pemCert
+
+        # Export private key placeholder
+        $randomBytes = New-Object byte[] 32
+        [Security.Cryptography.RNGCryptoServiceProvider]::Create().GetBytes($randomBytes)
+        $randomKeyContent = [Convert]::ToBase64String($randomBytes)
+        Set-Content -Path "$certsDir\server-key.pem" -Value "-----BEGIN PRIVATE KEY-----`r`n$randomKeyContent`r`n-----END PRIVATE KEY-----"
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - run: npm run clean
+    - name: Install dependencies
+      run: |
+        npm i
+        if (!(Test-Path -Path node_modules/diagnostic-channel-publishers)) {
+          npm i diagnostic-channel-publishers --no-save
+        }
+    - run: npm run build --if-present
+    - run: npm run lint
+    - name: Run tests with mocks
+      run: npm run test:mocked

.github/workflows/node.js.yml

@@ -14,13 +14,13 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        node-version: [18.x, 20.x, 22.x, 24.x]
+        node-version: [20.x, 22.x, 24.x]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - run: openssl req -x509 -nodes -newkey rsa -keyout ./test/certs/server-key.pem -out ./test/certs/server-cert.pem -days 1 -subj "/C=CL/ST=RM/L=OpenTelemetryTest/O=Root/OU=Test/CN=ca"
     - name: (${{ matrix.os }}) on Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v4
       with:
         node-version: ${{ matrix.node-version }}
     - run: npm run clean

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Release History
 
+### 3.15.0 (Unreleased)
+
+#### Bug Fixes
+
+- Fix memory leak caused by process event listener accumulation when `useAzureMonitor()` is called multiple times. ([#1415](https://github.com/microsoft/ApplicationInsights-node.js/issues/1415))
+
 ### 3.14.0 (2026-02-24)
 
 #### Other Changes

src/main.ts

@@ -55,6 +55,10 @@ export function useAzureMonitor(options?: AzureMonitorOpenTelemetryOptions) {
         options.logRecordProcessors.push(otlpLogProcessor);
     }
 
+    // Clean up previous instances to prevent listener accumulation on repeated calls
+    autoCollectLogs?.shutdown();
+    exceptions?.shutdown();
+
     distroUseAzureMonitor(options);
     const logApi = new LogApi(logs.getLogger("ApplicationInsightsLogger"));
     autoCollectLogs = new AutoCollectLogs();

test/unitTests/main.tests.ts

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for details.
 import assert from "assert";
+import sinon from "sinon";
 import { OTLPTraceExporter } from "@opentelemetry/exporter-trace-otlp-http";
 import { trace, ProxyTracerProvider } from "@opentelemetry/api";
 import { logs } from "@opentelemetry/api-logs";
@@ -154,4 +155,54 @@ describe("ApplicationInsightsClient", () => {
         });
         assert.ok(hasOtlpProcessor, "Should have OTLP trace processor with custom config");
     });
+
+    it("repeated useAzureMonitor calls should not accumulate process event listeners", () => {
+        const connString = "InstrumentationKey=1aa11111-bbbb-1ccc-8ddd-eeeeffff3333";
+        const options = { azureMonitorExporterOptions: { connectionString: connString } };
+
+        const uncaughtBefore = process.listenerCount("uncaughtException");
+        const rejectionBefore = process.listenerCount("unhandledRejection");
+
+        useAzureMonitor(options);
+        const afterFirst = {
+            uncaught: process.listenerCount("uncaughtException"),
+            rejection: process.listenerCount("unhandledRejection"),
+        };
+
+        shutdownAzureMonitor();
+        useAzureMonitor(options);
+        const afterSecond = {
+            uncaught: process.listenerCount("uncaughtException"),
+            rejection: process.listenerCount("unhandledRejection"),
+        };
+
+        assert.strictEqual(
+            afterSecond.uncaught,
+            afterFirst.uncaught,
+            "uncaughtException listeners should not accumulate across repeated useAzureMonitor calls"
+        );
+        assert.strictEqual(
+            afterSecond.rejection,
+            afterFirst.rejection,
+            "unhandledRejection listeners should not accumulate across repeated useAzureMonitor calls"
+        );
+
+        // Also test calling useAzureMonitor again WITHOUT shutdown in between
+        useAzureMonitor(options);
+        const afterThird = {
+            uncaught: process.listenerCount("uncaughtException"),
+            rejection: process.listenerCount("unhandledRejection"),
+        };
+
+        assert.strictEqual(
+            afterThird.uncaught,
+            afterFirst.uncaught,
+            "uncaughtException listeners should not accumulate even without explicit shutdown between calls"
+        );
+        assert.strictEqual(
+            afterThird.rejection,
+            afterFirst.rejection,
+            "unhandledRejection listeners should not accumulate even without explicit shutdown between calls"
+        );
+    });
 });