Fixed socket reuse issues in LatencyProbeService; improved logging in dashboard.js; updated documentation link; added favicon to HTML files; configured SignalR JSON serialization.

Author: rhamlett_microsoft

src/PerfProblemSimulator/Program.cs

@@ -123,7 +123,15 @@
 // Educational Note: This service demonstrates how thread pool starvation affects request
 // processing time. It runs on a dedicated thread (not the thread pool) to ensure it can
 // always measure latency, even during severe starvation conditions.
-builder.Services.AddHttpClient("LatencyProbe");
+builder.Services.AddHttpClient("LatencyProbe")
+    .ConfigurePrimaryHttpMessageHandler(() => new SocketsHttpHandler
+    {
+        // Disable connection pooling to avoid socket reuse issues on localhost
+        PooledConnectionLifetime = TimeSpan.Zero,
+        PooledConnectionIdleTimeout = TimeSpan.Zero,
+        // Allow connections to localhost
+        ConnectTimeout = TimeSpan.FromSeconds(5)
+    });
 builder.Services.AddHostedService<LatencyProbeService>();
 
 // -----------------------------------------------------------------------------

src/PerfProblemSimulator/Services/LatencyProbeService.cs

@@ -126,17 +126,26 @@ private void ProbeLoop(object? state)
     {
         var cancellationToken = (CancellationToken)state!;
 
-        // Wait a moment for the server to fully start
-        Thread.Sleep(2000);
+        // Wait for the server to fully start and accept connections
+        Thread.Sleep(5000);
 
         // Get the base URL (may need to refresh after server starts)
         var baseUrl = _baseUrl ?? GetProbeBaseUrl();
         _logger.LogInformation("Latency probe targeting: {BaseUrl}/api/health/probe", baseUrl);
 
-        // Create HttpClient with timeout
-        using var httpClient = _httpClientFactory.CreateClient("LatencyProbe");
-        httpClient.BaseAddress = new Uri(baseUrl);
-        httpClient.Timeout = TimeSpan.FromMilliseconds(RequestTimeoutMs);
+        // Create a handler that doesn't pool connections to avoid socket reuse issues
+        var handler = new SocketsHttpHandler
+        {
+            PooledConnectionLifetime = TimeSpan.Zero,
+            PooledConnectionIdleTimeout = TimeSpan.Zero,
+            ConnectTimeout = TimeSpan.FromSeconds(5)
+        };
+
+        using var httpClient = new HttpClient(handler)
+        {
+            BaseAddress = new Uri(baseUrl),
+            Timeout = TimeSpan.FromMilliseconds(RequestTimeoutMs)
+        };
 
         while (!cancellationToken.IsCancellationRequested)
         {

src/PerfProblemSimulator/wwwroot/documentation.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Performance Problem Simulator - Documentation</title>
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg">
     <link rel="stylesheet" href="css/dashboard.css">
     <style>
         /* Documentation-specific styles */

src/PerfProblemSimulator/wwwroot/favicon.svg

@@ -4,6 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Performance Problem Simulator - Dashboard</title>
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg">
     <link rel="stylesheet" href="css/dashboard.css">
     <!-- Chart.js for real-time graphs -->
     <script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.1/dist/chart.umd.min.js"></script>

src/PerfProblemSimulator/wwwroot/index.html

@@ -424,7 +424,11 @@ function updateCharts() {
  * This shows the impact of thread pool starvation on request processing time.
  */
 function handleLatencyUpdate(measurement) {
-    console.log('Received latency update:', measurement);
+    // Only log errors or significant latency, not every update
+    if (measurement.isError || measurement.isTimeout || measurement.latencyMs > 500) {
+        console.log('Latency update:', measurement);
+    }
+    
     const timestamp = new Date(measurement.timestamp);
     const latencyMs = measurement.latencyMs;
     const isTimeout = measurement.isTimeout;