added v1.4.47 release notes

[Aaronontheweb]

1.4.47 December 9th 2022

Akka.NET v1.4.47 is a maintenance patch for Akka.NET v1.4.46 that includes a variety of bug fixes, performance improvements, and new features.

Actor Telemetry

Starting in Akka.NET v1.4.47 local and remotely deployed actors will now emit events when being started, stopped, and restarted:

public interface IActorTelemetryEvent : INoSerializationVerificationNeeded, INotInfluenceReceiveTimeout
{
    /// <summary>
    /// The actor who emitted this event.
    /// </summary>
    IActorRef Subject {get;}
    
    /// <summary>
    /// The implementation type for this actor.
    /// </summary>
    Type ActorType { get; }
}

/// <summary>
/// Event emitted when actor starts.
/// </summary>
public sealed class ActorStarted : IActorTelemetryEvent
{
    public IActorRef Subject { get; }
    public Type ActorType { get; }
}

/// <summary>
/// Event emitted when actor shuts down.
/// </summary>
public sealed class ActorStopped : IActorTelemetryEvent
{
    public IActorRef Subject { get; }
    public Type ActorType { get; }
}

/// <summary>
/// Emitted when an actor restarts.
/// </summary>
public sealed class ActorRestarted : IActorTelemetryEvent
{
    public IActorRef Subject { get; }
    public Type ActorType { get; }
    
    public Exception Reason { get; }
}

These events will be consumed from popular Akka.NET observability and management tools such as Phobos and Petabridge.Cmd to help provide users with more accurate insights into actor workloads over time, but you can also consume these events yourself by subscribing to them via the EventStream:

// subscribe to all actor telemetry events
Context.System.EventStream.Subscribe(Self, typeof(IActorTelemetryEvent));

By default actor telemetry is disabled - to enable it you'll need to turn it on via the following HOCON setting:

akka.actor.telemetry.enabled = on

The performance impact of enabling telemetry is negligible, as you can see via our benchmarks.

Fixes and Updates

• Akka.Streams: Fixed System.NotSupportedException when disposing stage with materialized IAsyncEnumerable
• Akka.Streams: ReuseLatest stage to repeatedly emit the most recent value until a newer one is pushed
• Akka.Remote: eliminate ActorPath.ToSerializationFormat UID allocations - should provide a noticeable Akka.Remote performance improvement.
• Akka.Remote: Remoting and an exception as a payload message - Exception types are now serialized properly inside Status.Failure messages over the wire. Status.Failure and Status.Success messages are now managed by Protobuf - so you might see some deserialization errors while upgrading if those types are being exchanged over the wire.
• Akka.TestKit: TestActorRef can not catch exceptions on asynchronous methods

You can see the full set of tracked issues for Akka.NET v1.4.47 here.

COMMITS	LOC+	LOC-	AUTHOR
10	2027	188	Aaron Stannard
1	157	10	Gregorius Soedharmo

[Arkatufus]

LGTM