[AppInsights] delaying QuickPulse initialization to help with cold start

src/Microsoft.Azure.WebJobs.Logging.ApplicationInsights/ApplicationInsightsLoggerOptions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
+using System;
 using Microsoft.ApplicationInsights.SnapshotCollector;
 using Microsoft.ApplicationInsights.WindowsServer.Channel.Implementation;
 using Microsoft.Azure.WebJobs.Hosting;
@@ -31,6 +32,12 @@ public class ApplicationInsightsLoggerOptions : IOptionsFormatter
         /// </summary>
         public string QuickPulseAuthenticationApiKey { get; set; }
 
+        /// <summary>
+        /// Gets or sets the time to delay Quick Pulse (Live Metrics) initialization. Delaying this initialization
+        /// can result in decreased application startup time. Default value is 15 seconds.
+        /// </summary>
+        public TimeSpan QuickPulseInitializationDelay { get; set; } = TimeSpan.FromSeconds(15);
+
         /// <summary>
         /// Gets or sets flag that enables Kudu performance counters collection.
         /// https://github.com/projectkudu/kudu/wiki/Perf-Counters-exposed-as-environment-variables.
@@ -98,6 +105,7 @@ public string Format()
                 { nameof(SnapshotConfiguration), snapshot },
                 { nameof(EnablePerformanceCountersCollection), EnablePerformanceCountersCollection},
                 { nameof(HttpAutoCollectionOptions), httpOptions},
+                { nameof(QuickPulseInitializationDelay), QuickPulseInitializationDelay }
             };
 
             return options.ToString(Formatting.Indented);

src/Microsoft.Azure.WebJobs.Logging.ApplicationInsights/Extensions/ApplicationInsightsServiceCollectionExtensions.cs

@@ -14,8 +14,8 @@
 using Microsoft.ApplicationInsights.Extensibility.Implementation.ApplicationId;
 using Microsoft.ApplicationInsights.Extensibility.PerfCounterCollector;
 using Microsoft.ApplicationInsights.Extensibility.PerfCounterCollector.QuickPulse;
-using Microsoft.ApplicationInsights.SnapshotCollector;
 using Microsoft.ApplicationInsights.Extensibility.W3C;
+using Microsoft.ApplicationInsights.SnapshotCollector;
 using Microsoft.ApplicationInsights.WindowsServer;
 using Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel;
 using Microsoft.Azure.WebJobs.Logging.ApplicationInsights;
@@ -57,13 +57,18 @@ public static IServiceCollection AddApplicationInsights(this IServiceCollection
             services.AddSingleton<ITelemetryInitializer, MetricSdkVersionTelemetryInitializer>();
 
             services.AddSingleton<ITelemetryModule, QuickPulseTelemetryModule>();
-
+            services.AddSingleton<QuickPulseInitializationScheduler>();
+
             services.AddSingleton<ITelemetryModule>(provider =>
             {
                 ApplicationInsightsLoggerOptions options = provider.GetService<IOptions<ApplicationInsightsLoggerOptions>>().Value;
                 if (options.EnablePerformanceCountersCollection)
                 {
-                    return new PerformanceCollectorModule();
+                    return new PerformanceCollectorModule
+                    {
+                        // Disabling this can improve cold start times
+                        EnableIISExpressPerformanceCounters = false
+                    };
                 }
 
                 return NullTelemetryModule.Instance;
@@ -132,7 +137,7 @@ public static IServiceCollection AddApplicationInsights(this IServiceCollection
 
                 var activeConfig = TelemetryConfiguration.Active;
                 if (!string.IsNullOrEmpty(options.InstrumentationKey) &&
-                    string.IsNullOrEmpty(activeConfig.InstrumentationKey))
+                string.IsNullOrEmpty(activeConfig.InstrumentationKey))
                 {
                     activeConfig.InstrumentationKey = options.InstrumentationKey;
                 }
@@ -158,22 +163,22 @@ public static IServiceCollection AddApplicationInsights(this IServiceCollection
                     provider.GetServices<ITelemetryInitializer>(),
                     provider.GetServices<ITelemetryModule>(),
                     appIdProvider,
-                    filterOptions);
+                    filterOptions,
+                    provider.GetService<QuickPulseInitializationScheduler>());
 
                 return config;
             });
 
             services.AddSingleton<TelemetryClient>(provider =>
-                {
-                    TelemetryConfiguration configuration = provider.GetService<TelemetryConfiguration>();
-                    TelemetryClient client = new TelemetryClient(configuration);
+            {
+                TelemetryConfiguration configuration = provider.GetService<TelemetryConfiguration>();
+                TelemetryClient client = new TelemetryClient(configuration);
 
-                    ISdkVersionProvider versionProvider = provider.GetService<ISdkVersionProvider>();
-                    client.Context.GetInternalContext().SdkVersion = versionProvider?.GetSdkVersion();
+                ISdkVersionProvider versionProvider = provider.GetService<ISdkVersionProvider>();
+                client.Context.GetInternalContext().SdkVersion = versionProvider?.GetSdkVersion();
 
-                    return client;
-                }
-            );
+                return client;
+            });
 
             services.AddSingleton<ILoggerProvider, ApplicationInsightsLoggerProvider>();
 
@@ -215,7 +220,8 @@ private static void SetupTelemetryConfiguration(
             IEnumerable<ITelemetryInitializer> telemetryInitializers,
             IEnumerable<ITelemetryModule> telemetryModules,
             IApplicationIdProvider applicationIdProvider,
-            LoggerFilterOptions filterOptions)
+            LoggerFilterOptions filterOptions,
+            QuickPulseInitializationScheduler delayer)
         {
             if (options.InstrumentationKey != null)
             {
@@ -249,9 +255,14 @@ private static void SetupTelemetryConfiguration(
                     {
                         quickPulseModule.AuthenticationApiKey = options.QuickPulseAuthenticationApiKey;
                     }
-                }
 
-                module.Initialize(configuration);
+                    // QuickPulse can have a startup performance hit, so delay its initialization.
+                    delayer.ScheduleInitialization(() => module.Initialize(configuration), options.QuickPulseInitializationDelay);
+                }
+                else
+                {
+                    module.Initialize(configuration);
+                }
             }
 
             QuickPulseTelemetryProcessor quickPulseProcessor = null;

src/Microsoft.Azure.WebJobs.Logging.ApplicationInsights/QuickPulseInitializationScheduler.cs

@@ -0,0 +1,48 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.Azure.WebJobs.Logging.ApplicationInsights
+{
+    // We need to be able to delay initialization in Functions for cold start, 
+    // so perform this initialization in a service that can handle cancellation.
+    internal class QuickPulseInitializationScheduler : IDisposable
+    {
+        private readonly CancellationTokenSource _cts = new CancellationTokenSource();
+        private bool _disposed = false;
+        private object _lock = new object();
+
+        public void ScheduleInitialization(Action initialization, TimeSpan delay)
+        {
+            Task.Delay(delay, _cts.Token)
+                .ContinueWith(_ =>
+                {
+                    lock (_lock)
+                    {
+                        if (!_disposed)
+                        {
+                            initialization();
+                        }
+                    }
+                },
+                TaskContinuationOptions.OnlyOnRanToCompletion);
+        }
+
+        public void Dispose()
+        {
+            lock (_lock)
+            {
+                if (!_disposed)
+                {
+                    _cts.Cancel();
+                    _cts.Dispose();
+
+                    _disposed = true;
+                }
+            }
+        }
+    }
+}

test/Microsoft.Azure.WebJobs.Host.EndToEndTests/ApplicationInsights/ApplicationInsightsEndToEndTests.cs

@@ -85,6 +85,7 @@ private IHost ConfigureHost(LogLevel minLevel = LogLevel.Information, HttpAutoCo
                     {
                         o.InstrumentationKey = _mockApplicationInsightsKey;
                         o.HttpAutoCollectionOptions = httpOptions;
+                        o.QuickPulseInitializationDelay = TimeSpan.FromSeconds(1);
                     });
                 })
                 .ConfigureServices(services =>
@@ -465,10 +466,10 @@ public async Task ApplicationInsights_HttpRequestTrackingByAIAutoCollector(strin
                 request.Headers.Add("traceparent", "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01");
 
                 var mockHttpContext = new DefaultHttpContext();
-                mockHttpContext.Connection.RemoteIpAddress = new IPAddress(new byte[] {1, 2, 3, 4});
+                mockHttpContext.Connection.RemoteIpAddress = new IPAddress(new byte[] { 1, 2, 3, 4 });
 
                 // simulate functions behavior to set request on the scope
-                using (var _ = logger.BeginScope(new Dictionary<string, object> { ["MS_HttpRequest"] = mockHttpContext.Request}))
+                using (var _ = logger.BeginScope(new Dictionary<string, object> { ["MS_HttpRequest"] = mockHttpContext.Request }))
                 {
                     await client.SendAsync(request);
                 }
@@ -489,7 +490,7 @@ await TestHelpers.Await(() =>
                 Assert.True(functionRequest.Duration.TotalMilliseconds >= functionDuration);
                 Assert.Equal("1.2.3.4", functionRequest.Context.Location.Ip);
                 Assert.Equal("http://localhost/some/path", functionRequest.Url.ToString());
-                
+
                 ValidateRequest(
                     functionRequest,
                     testName,
@@ -665,7 +666,7 @@ await TestHelpers.Await(() =>
                 }
             }
         }
-        
+
         // Test Functions
         [NoAutomaticTrigger]
         public static void TestApplicationInsightsInformation(string input, TraceWriter trace, ILogger logger)
@@ -719,7 +720,7 @@ public static void TestApplicationInsightsExplicitCall(ILogger logger)
             TelemetryClient telemetryClient = new TelemetryClient(); // use TelemetryConfiguration.Active
             telemetryClient.TrackEvent("custom event");
         }
-        
+
         [NoAutomaticTrigger]
         public static void TestApplicationInsightsDisposeRequestsModule(string input, ILogger logger)
         {
@@ -1012,7 +1013,7 @@ private static void ValidateRequest(RequestTelemetry telemetry, string operation
         }
 
         private static void ValidateSdkVersion(ITelemetry telemetry, string prefix = null)
-        {            
+        {
             Assert.StartsWith($"{prefix}webjobs:", telemetry.Context.GetInternalContext().SdkVersion);
         }
 
@@ -1106,7 +1107,7 @@ public void Configure(IApplicationBuilder app, AspNetCore.Hosting.IHostingEnviro
 
                     try
                     {
-                        await Host.GetJobHost().CallAsync(methodInfo, new {input = "input"});
+                        await Host.GetJobHost().CallAsync(methodInfo, new { input = "input" });
                     }
                     catch
                     {