Configured the metrics hub to be more aggressive about closing stale connections.

Author: rhamlett_microsoft

src/PerfProblemSimulator/Program.cs

@@ -55,7 +55,17 @@
 // Add SignalR for real-time dashboard updates
 // Educational Note: SignalR provides WebSocket-based real-time communication,
 // which is essential for showing live metrics on the dashboard.
-builder.Services.AddSignalR()
+builder.Services.AddSignalR(options =>
+    {
+        // Configure timeouts to prevent connections from hanging indefinitely
+        // during simulated performance problems (thread starvation, crashes, etc.)
+        options.ClientTimeoutInterval = TimeSpan.FromSeconds(60);   // Disconnect if no message for 60s
+        options.KeepAliveInterval = TimeSpan.FromSeconds(15);       // Send keepalive every 15s
+        options.HandshakeTimeout = TimeSpan.FromSeconds(15);        // Handshake must complete in 15s
+        
+        // Enable detailed errors for debugging (disable in production)
+        options.EnableDetailedErrors = builder.Environment.IsDevelopment();
+    })
     .AddJsonProtocol(options =>
     {
         // Use camelCase to match controller JSON serialization

src/PerfProblemSimulator/wwwroot/js/dashboard.js

@@ -93,6 +93,14 @@ async function initializeSignalR() {
         .configureLogging(signalR.LogLevel.Information)
         .build();
 
+    // Configure timeouts to detect server unresponsiveness faster
+    // serverTimeoutInMilliseconds: How long client waits for server response before disconnecting
+    // Must be at least 2x the server's KeepAliveInterval (15s), so we use 45s
+    state.connection.serverTimeoutInMilliseconds = 45000;
+    
+    // keepAliveIntervalInMilliseconds: How often client sends ping to server
+    state.connection.keepAliveIntervalInMilliseconds = 15000;
+
     // Handle connection state changes
     state.connection.onreconnecting(error => {
         updateConnectionStatus('connecting', 'Reconnecting...');
@@ -106,7 +114,9 @@ async function initializeSignalR() {
 
     state.connection.onclose(error => {
         updateConnectionStatus('disconnected', 'Disconnected');
-        logEvent('error', 'Connection closed. Refresh page to reconnect.');
+        logEvent('warning', 'Connection closed. Attempting to reconnect...');
+        // Auto-reconnect after close (handles cases where withAutomaticReconnect gives up)
+        setTimeout(initializeSignalR, CONFIG.reconnectDelayMs);
     });
 
     // Register message handlers