Fully Adaptive Stateless Worker

src/Orleans.Core.Abstractions/Concurrency/GrainAttributeConcurrency.cs

@@ -57,11 +57,28 @@ public sealed class StatelessWorkerAttribute : PlacementAttribute, IGrainPropert
         /// <summary>
         /// Initializes a new instance of the <see cref="StatelessWorkerAttribute"/> class.
         /// </summary>
-        /// <param name="maxLocalWorkers">
-        /// The maximum local workers.
-        /// </param>
+        /// <param name="maxLocalWorkers">The maximum local workers.</param>
+        /// <param name="proactiveWorkerCollection">Tries to collects idle workers before the configured collection age.</param>
+        public StatelessWorkerAttribute(int maxLocalWorkers, bool proactiveWorkerCollection)
+            : base(new StatelessWorkerPlacement(maxLocalWorkers, proactiveWorkerCollection))
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StatelessWorkerAttribute"/> class.
+        /// </summary>
+        /// <param name="proactiveWorkerCollection">Tries to collects idle workers before the configured collection age.</param>
+        public StatelessWorkerAttribute(bool proactiveWorkerCollection)
+            : base(new StatelessWorkerPlacement(-1, proactiveWorkerCollection))
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StatelessWorkerAttribute"/> class.
+        /// </summary>
+        /// <param name="maxLocalWorkers">The maximum local workers.</param>
         public StatelessWorkerAttribute(int maxLocalWorkers)
-            : base(new StatelessWorkerPlacement(maxLocalWorkers))
+            : base(new StatelessWorkerPlacement(maxLocalWorkers, false))
         {
         }
 

src/Orleans.Core.Abstractions/Core/IGrainBase.cs

@@ -290,14 +290,19 @@ public enum DeactivationReasonCode : byte
         ApplicationError,
 
         /// <summary>
-        /// The application requested that this activation deactivate.
+        /// The application requested to deactivate this activation.
         /// </summary>
         ApplicationRequested,
 
         /// <summary>
         /// This activation is migrating to a new location.
         /// </summary>
         Migrating,
+
+        /// <summary>
+        /// The runtime requested to deactivate this activation.
+        /// </summary>
+        RuntimeRequested
     }
 
     internal static class DeactivationReasonCodeExtensions

src/Orleans.Core.Abstractions/Placement/StatelessWorkerPlacement.cs

@@ -12,6 +12,8 @@ namespace Orleans.Runtime
     internal sealed class StatelessWorkerPlacement : PlacementStrategy
     {
         private const string MaxLocalPropertyKey = "max-local-instances";
+        private const string ProactiveCollectionPropertyKey = "proactive-removal";
+
         private static readonly int DefaultMaxStatelessWorkers = Environment.ProcessorCount;
 
         /// <inheritdoc/>
@@ -23,49 +25,70 @@ internal sealed class StatelessWorkerPlacement : PlacementStrategy
         [Id(0)]
         public int MaxLocal { get; private set; }
 
+        /// <summary>
+        /// Instructs the runtime wether it should proactive collect idle workers or let them be collected by the activation collector.
+        /// </summary>
+        [Id(1)]
+        public bool ProactiveWorkerCollection { get; private set; }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="StatelessWorkerPlacement"/> class.
         /// </summary>
         /// <param name="maxLocal">
         /// The maximum number of local instances which can be simultaneously active for a given grain.
         /// </param>
-        internal StatelessWorkerPlacement(int maxLocal)
+        /// <param name="proactiveWorkerCollection">
+        /// Wether to proactively collect workers if they are inactive, or let them be collected by the activation collector.
+        /// </param>
+        internal StatelessWorkerPlacement(int maxLocal, bool proactiveWorkerCollection)
         {
             // If maxLocal was not specified on the StatelessWorkerAttribute,
             // we will use the defaultMaxStatelessWorkers, which is System.Environment.ProcessorCount.
             this.MaxLocal = maxLocal > 0 ? maxLocal : DefaultMaxStatelessWorkers;
+            this.ProactiveWorkerCollection = proactiveWorkerCollection;
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="StatelessWorkerPlacement"/> class.
         /// </summary>
-        public StatelessWorkerPlacement() : this(-1)
+        public StatelessWorkerPlacement() : this(-1, false)
         {
         }
 
         /// <inheritdoc/>
-        public override string ToString() => $"StatelessWorkerPlacement(max={MaxLocal})";
+        public override string ToString() => $"StatelessWorkerPlacement(max={MaxLocal} | (proactive={ProactiveWorkerCollection}))";
 
         /// <inheritdoc/>
         public override void Initialize(GrainProperties properties)
         {
             base.Initialize(properties);
-            if (properties.Properties.TryGetValue(MaxLocalPropertyKey, out var value)
-                && !string.IsNullOrWhiteSpace(value))
+
+            if (properties.Properties.TryGetValue(MaxLocalPropertyKey, out var value) &&
+                !string.IsNullOrWhiteSpace(value))
             {
                 if (int.TryParse(value, out var maxLocal))
                 {
-                    this.MaxLocal = maxLocal;
+                    MaxLocal = maxLocal;
+                }
+            }
+
+            if (properties.Properties.TryGetValue(ProactiveCollectionPropertyKey, out var proactive) &&
+                !string.IsNullOrWhiteSpace(proactive))
+            {
+                if (bool.TryParse(proactive, out var isProactive))
+                {
+                    ProactiveWorkerCollection = isProactive;
                 }
             }
         }
 
         /// <inheritdoc/>
         public override void PopulateGrainProperties(IServiceProvider services, Type grainClass, GrainType grainType, Dictionary<string, string> properties)
         {
-            properties[MaxLocalPropertyKey] = this.MaxLocal.ToString(CultureInfo.InvariantCulture);
+            properties[MaxLocalPropertyKey] = MaxLocal.ToString(CultureInfo.InvariantCulture);
+            properties[ProactiveCollectionPropertyKey] = ProactiveWorkerCollection.ToString();
 
             base.PopulateGrainProperties(services, grainClass, grainType, properties);
         }
     }
-}
+}

src/Orleans.Runtime/Catalog/GrainTypeSharedContext.cs

@@ -33,6 +33,7 @@ public GrainTypeSharedContext(
         IOptions<SiloMessagingOptions> messagingOptions,
         IOptions<GrainCollectionOptions> collectionOptions,
         IOptions<SchedulingOptions> schedulingOptions,
+        IOptions<StatelessWorkerOptions> statelessWorkerOptions,
         IGrainRuntime grainRuntime,
         ILoggerFactory loggerFactory,
         GrainReferenceActivator grainReferenceActivator,
@@ -56,6 +57,7 @@ public GrainTypeSharedContext(
         var grainDirectoryResolver = serviceProvider.GetRequiredService<GrainDirectoryResolver>();
         GrainDirectory = PlacementStrategy.IsUsingGrainDirectory ? grainDirectoryResolver.Resolve(grainType) : null;
         SchedulingOptions = schedulingOptions.Value;
+        StatelessWorkerOptions = statelessWorkerOptions.Value;
         Runtime = grainRuntime;
         MigrationManager = _serviceProvider.GetService<IActivationMigrationManager>();
 
@@ -181,6 +183,11 @@ public void SetComponent<TComponent>(TComponent? instance)
     /// </summary>
     public SchedulingOptions SchedulingOptions { get; }
 
+    /// <summary>
+    /// Gets the stateless worker options.
+    /// </summary>
+    public StatelessWorkerOptions StatelessWorkerOptions { get; }
+
     /// <summary>
     /// Gets the grain runtime.
     /// </summary>