Fix memory leak: clean up listeners on repeated useAzureMonitor calls (#1493)

* Fix memory leak: clean up listeners on repeated useAzureMonitor calls

When useAzureMonitor() is called multiple times, old AutoCollectExceptions
and AutoCollectLogs instances were silently overwritten without cleanup,
causing process event listener accumulation and retaining old LogApi
instances (and their downstream spans/connection metadata) in memory.

This adds shutdown of previous instances before re-initialization and
a test verifying listeners do not accumulate.

Fixes: #1415

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix flaky test infrstructure.

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: JacksonWeber

.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-x86.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-windows.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

.github/workflows/node.js.yml

@@ -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

CHANGELOG.md

@@ -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();

src/main.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"
+        );
+    });
 });