Add new ChannelTaskScheduler Extension (#5403)

* add new ChannelTaskScheduler extension and set as the new 'channel-executor'

* rallback dependancy version and add comments

Co-authored-by: Aaron Stannard <aaron@petabridge.com>

src/core/Akka.API.Tests/CoreAPISpec.ApproveCore.approved.txt

@@ -2509,6 +2509,22 @@ namespace Akka.Dispatch
         public System.TimeSpan PushTimeout { get; }
         public override Akka.Dispatch.MessageQueues.IMessageQueue Create(Akka.Actor.IActorRef owner, Akka.Actor.ActorSystem system) { }
     }
+    public sealed class ChannelTaskScheduler : Akka.Actor.IExtension, System.IDisposable
+    {
+        public ChannelTaskScheduler(Akka.Actor.ExtendedActorSystem system) { }
+        public System.Threading.Tasks.TaskScheduler High { get; }
+        public System.Threading.Tasks.TaskScheduler Idle { get; }
+        public System.Threading.Tasks.TaskScheduler Low { get; }
+        public System.Threading.Tasks.TaskScheduler Normal { get; }
+        public void Dispose() { }
+        public static Akka.Dispatch.ChannelTaskScheduler Get(Akka.Actor.ActorSystem system) { }
+        public System.Threading.Tasks.TaskScheduler GetScheduler(Akka.Dispatch.TaskSchedulerPriority priority) { }
+    }
+    public sealed class ChannelTaskSchedulerProvider : Akka.Actor.ExtensionIdProvider<Akka.Dispatch.ChannelTaskScheduler>
+    {
+        public ChannelTaskSchedulerProvider() { }
+        public override Akka.Dispatch.ChannelTaskScheduler CreateExtension(Akka.Actor.ExtendedActorSystem system) { }
+    }
     public sealed class CurrentSynchronizationContextDispatcher : Akka.Dispatch.Dispatcher
     {
         public CurrentSynchronizationContextDispatcher(Akka.Dispatch.MessageDispatcherConfigurator configurator, string id, int throughput, System.Nullable<long> throughputDeadlineTime, Akka.Dispatch.ExecutorServiceFactory executorServiceFactory, System.TimeSpan shutdownTimeout) { }
@@ -2677,6 +2693,18 @@ namespace Akka.Dispatch
         public RejectedExecutionException(string message = null, System.Exception inner = null) { }
         protected RejectedExecutionException(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context) { }
     }
+    public enum TaskSchedulerPriority
+    {
+        None = 0,
+        Idle = 4,
+        Background = 4,
+        Low = 5,
+        BelowNormal = 6,
+        Normal = 8,
+        AboveNormal = 10,
+        High = 13,
+        Realtime = 24,
+    }
     public class ThreadPoolConfig
     {
         public ThreadPoolConfig(Akka.Configuration.Config config) { }

src/core/Akka.Remote/Configuration/Remote.conf

@@ -586,20 +586,21 @@ akka {
 
     default-remote-dispatcher {
 	    executor = fork-join-executor
-      fork-join-executor {
-        parallelism-min = 2
-        parallelism-factor = 0.5
-        parallelism-max = 16
-      }
+        fork-join-executor {
+            parallelism-min = 2
+            parallelism-factor = 0.5
+            parallelism-max = 16
+        }
+        channel-executor.priority = "high"
     }
 
     backoff-remote-dispatcher {
 	    executor = fork-join-executor
-      fork-join-executor {
-        parallelism-min = 2
-        parallelism-max = 2
-      }
+        fork-join-executor {
+            parallelism-min = 2
+            parallelism-max = 2
+        }
+        channel-executor.priority = "low"
     }
   }
-
-}
+}

src/core/Akka/Akka.csproj

@@ -19,6 +19,7 @@
     <PackageReference Include="System.Collections.Immutable" Version="5.0.0" />
     <PackageReference Include="System.Reflection.Emit" Version="4.7.0" />
       <PackageReference Include="System.Collections.Immutable" Version="5.0.0" />
+      <PackageReference Include="System.Threading.Channels" Version="5.0.0" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == '$(NetStandardLibVersion)'">

src/core/Akka/Configuration/Pigeon.conf

@@ -269,6 +269,15 @@ akka {
       }
     }
 
+    channel-scheduler {
+        parallelism-min = 4    #same as for ForkJoinDispatcher
+        parallelism-factor = 1 #same as for ForkJoinDispatcher
+        parallelism-max = 64   #same as for ForkJoinDispatcher
+        work-max = 10          #max executed work items in sequence until priority loop
+	    work-interval = 500    #time target of executed work items in ms
+	    work-step = 2          #target work item count in interval / burst
+    }
+
     #used for GUI applications
     synchronized-dispatcher {
         type = "SynchronizedDispatcher"
@@ -377,6 +386,7 @@ akka {
         parallelism-factor = 1.0
         parallelism-max = 64
       }
+      channel-executor.priority = "high"
     }
 
     default-blocking-io-dispatcher {

src/core/Akka/Dispatch/AbstractDispatcher.cs

@@ -120,19 +120,18 @@ internal sealed class ChannelExecutorConfigurator : ExecutorServiceConfigurator
     {
         public ChannelExecutorConfigurator(Config config, IDispatcherPrerequisites prerequisites) : base(config, prerequisites)
         {
-            var fje = config.GetConfig("fork-join-executor");
-            MaxParallelism = ThreadPoolConfig.ScaledPoolSize(
-                        fje.GetInt("parallelism-min"), 
-                        fje.GetDouble("parallelism-factor", 1.0D), // the scalar-based factor to scale the threadpool size to 
-                        fje.GetInt("parallelism-max"));
+            var cfg = config.GetConfig("channel-executor");
+            Priority = (TaskSchedulerPriority)Enum.Parse(typeof(TaskSchedulerPriority), cfg.GetString("priority", "normal"), true);
         }
 
-        public int MaxParallelism {get;}
+        public TaskSchedulerPriority Priority { get; }
 
         public override ExecutorService Produce(string id)
         {
-            Prerequisites.EventStream.Publish(new Debug($"ChannelExecutor-[id]", typeof(FixedConcurrencyTaskScheduler), $"Launched Dispatcher [{id}] with MaxParallelism=[{MaxParallelism}]"));
-            return new TaskSchedulerExecutor(id, new FixedConcurrencyTaskScheduler(MaxParallelism));
+            Prerequisites.EventStream.Publish(new Debug($"ChannelExecutor-[{id}]", typeof(TaskSchedulerExecutor), $"Launched Dispatcher [{id}] with Priority[{Priority}]"));
+
+            var scheduler = ChannelTaskScheduler.Get(Prerequisites.Settings.System).GetScheduler(Priority);
+            return new TaskSchedulerExecutor(id, scheduler);
         }
     }