Fixing storage traffic issue for SC

src/WebJobs.Extensions.DurableTask/DurableTaskJobHostConfigurationExtensions.cs

@@ -126,7 +126,9 @@ internal static IWebJobsBuilder AddDurableScaleForTrigger(this IWebJobsBuilder b
                 provider = new DurableTaskTriggersScaleProvider(serviceProvider.GetService<IOptions<DurableTaskOptions>>(), serviceProvider.GetService<INameResolver>(), serviceProvider.GetService<ILoggerFactory>(), serviceProvider.GetService<IEnumerable<IDurabilityProviderFactory>>(), triggerMetadata);
                 return provider;
             });
-            builder.Services.AddSingleton<IScaleMonitorProvider>(serviceProvider => serviceProvider.GetServices<DurableTaskTriggersScaleProvider>().Single(x => x == provider));
+
+            // Commenting out incremental scale model for hotfix release 3.0.0-rc.4, SC uses TBS by default
+            // builder.Services.AddSingleton<IScaleMonitorProvider>(serviceProvider => serviceProvider.GetServices<DurableTaskTriggersScaleProvider>().Single(x => x == provider));
             builder.Services.AddSingleton<ITargetScalerProvider>(serviceProvider => serviceProvider.GetServices<DurableTaskTriggersScaleProvider>().Single(x => x == provider));
             return builder;
         }

src/WebJobs.Extensions.DurableTask/Listener/DurableTaskMetricsProvider.cs

@@ -17,6 +17,8 @@ internal class DurableTaskMetricsProvider
         private readonly string hubName;
         private readonly ILogger logger;
         private readonly StorageAccountClientProvider storageAccountClientProvider;
+        private PerformanceHeartbeat heartbeat;
+        private DateTime heartbeatTimeStamp;
 
         private DisconnectedPerformanceMonitor performanceMonitor;
 
@@ -30,25 +32,32 @@ public DurableTaskMetricsProvider(
             this.logger = logger;
             this.performanceMonitor = performanceMonitor;
             this.storageAccountClientProvider = storageAccountClientProvider;
+            this.heartbeat = null;
+            this.heartbeatTimeStamp = DateTime.MinValue;
         }
 
         public virtual async Task<DurableTaskTriggerMetrics> GetMetricsAsync()
         {
             DurableTaskTriggerMetrics metrics = new DurableTaskTriggerMetrics();
 
             // Durable stores its own metrics, so we just collect them here
-            PerformanceHeartbeat heartbeat = null;
             try
             {
                 DisconnectedPerformanceMonitor performanceMonitor = this.GetPerformanceMonitor();
-                heartbeat = await performanceMonitor.PulseAsync();
+
+                // We only want to call PulseAsync every 5 seconds
+                if (this.heartbeat == null || DateTime.UtcNow > this.heartbeatTimeStamp.AddSeconds(5))
+                {
+                    this.heartbeat = await performanceMonitor.PulseAsync();
+                    this.heartbeatTimeStamp = DateTime.UtcNow;
+                }
             }
             catch (Exception e) when (e.InnerException is RequestFailedException)
             {
                 this.logger.LogWarning("{details}. HubName: {hubName}.", e.ToString(), this.hubName);
             }
 
-            if (heartbeat != null)
+            if (this.heartbeat != null)
             {
                 metrics.PartitionCount = heartbeat.PartitionCount;
                 metrics.ControlQueueLengths = JsonConvert.SerializeObject(heartbeat.ControlQueueLengths);