v1.4.19 Akka.NET Release

[Aaronontheweb]

1.4.19 April 28 2021

Maintenance Release for Akka.NET 1.4

Akka.NET v1.4.19 is a substantial release that includes a number of critical Akka.Cluster fixes, baseline Akka.NET performance improvements, and entirely new dispatcher that has shown to improve performance when used across all of the major actor groups that run both inside the /user hierarchy and the /system actor hierarchy as well.

Akka.Cluster Improvements
One of the most demanding issues of the v1.4.19 release was "Akka.Cluster: quarantining / reachability changes appear to be extremely sensitive" - and this is because debugging this issue touched so many different parts of Akka.Cluster.

We ultimately solved the problem - it is now quite feasible to rapidly scale an Akka.NET cluster from ~10 nodes to 50+ nodes without having a huge number of quarantines, accidentally downed nodes, and so on.

Here's the full set of fixes that went into resolving this issue:

• Added PhiAccrualFailureDetector warning logging for slow heartbeats
• measure Akka.Cluster heartbeat timings, hardened Akka.Cluster serialization
• ClusterStressSpec and Cluster Failure Detector Cleanup
• Akka.Cluster: improve HeartbeatNodeRing performance
• Akka.Cluster: Turned HeatbeatNodeRing into struct
• Akka.Cluster: Configure duration for applying MemberStatus.WeaklyUp to joining nodes
• Akka.Cluster: Performance optimize VectorClock
• Akka.Cluster: Refactored Gossip into MembershipState
• Akka.Remote: Clean up bad outbound ACKs in Akka.Remote

Akka.Cluster is now much more robust, faster, and capable of scaling up and down much more efficiently than in previous releases.

ChannelExecutor and Akka Performance Improvements
In addition to improving Akka.Cluster, we also made substantial improvements to constructs found inside Akka.NET core itself:

• Perf optimize ActorSelection - 20% throughput improvement, 25% memory consumption improvement
• fixed N-1 error inside Mailbox
• Introduce ChannelExecutor

In Akka.NET v1.4.19 we introduce an opt-in feature, the ChannelExecutor - a new dispatcher type that re-uses the same configuration as a ForkJoinDispatcher but runs entirely on top of the .NET ThreadPool and is able to take advantage of dynamic thread pool scaling to size / resize workloads on the fly.

In order to get the most use out of the ChannelExecutor, the default actor dispatcher, the internal dispatcher, and the Akka.Remote dispatchers all need to run on it - and you can see the latest configuration settings and guidance for that here in our documentation: https://getakka.net/articles/actors/dispatchers.html#channelexecutor

But a copy of today's configuration is included below - you can enable this feature inside your Akka.NET applications via the following HOCON:

akka.actor.default-dispatcher = {
    executor = channel-executor
    fork-join-executor { #channelexecutor will re-use these settings
      parallelism-min = 2
      parallelism-factor = 1
      parallelism-max = 64
    }
}

akka.actor.internal-dispatcher = {
    executor = channel-executor
    throughput = 5
    fork-join-executor {
      parallelism-min = 4
      parallelism-factor = 1.0
      parallelism-max = 64
    }
}

akka.remote.default-remote-dispatcher {
    type = Dispatcher
    executor = channel-executor
    fork-join-executor {
      parallelism-min = 2
      parallelism-factor = 0.5
      parallelism-max = 16
    }
}

akka.remote.backoff-remote-dispatcher {
  executor = channel-executor
  fork-join-executor {
    parallelism-min = 2
    parallelism-max = 2
  }
}

We are looking for feedback on how well the ChannelExecutor works in real world applications here: #4983

Hyperion v0.10 and Improvements
We also released Hyperion v0.10.0 and v0.10.1 as part of the Akka.NET v1.4.19 sprint, and this includes some useful changes for Akka.NET users who are trying to build cross-platform (.NET Framework + .NET Core / .NET 5) applications and need to handle all of the idiosyncrasies those platforms introduced by changing the default namespaces on primitive types such as string and int.

We have also introduced a new Setup type designed to make it easy to resolve some of these "cross platform" serialization concerns programmatically when configuring Hyperion for use inside Akka.NET:

#if NETFRAMEWORK
var hyperionSetup = HyperionSerializerSetup.Empty
    .WithPackageNameOverrides(new Func<string, string>[]
    {
        str => str.Contains("System.Private.CoreLib,%core%")
            ? str.Replace("System.Private.CoreLib,%core%", "mscorlib,%core%") : str
    }
#elif NETCOREAPP
var hyperionSetup = HyperionSerializerSetup.Empty
    .WithPackageNameOverrides(new Func<string, string>[]
    {
        str => str.Contains("mscorlib,%core%")
            ? str.Replace("mscorlib,%core%", "System.Private.CoreLib,%core%") : str
    }
#endif

var bootstrap = BootstrapSetup.Create().And(hyperionSetup);
var system = ActorSystem.Create("actorSystem", bootstrap);

See the full documentation for this feature here: https://getakka.net/articles/networking/serialization.html#cross-platform-serialization-compatibility-in-hyperion

To see the full set of fixes in Akka.NET v1.4.19, please see the milestone on Github.

COMMITS	LOC+	LOC-	AUTHOR
38	6092	4422	Aaron Stannard
13	2231	596	Gregorius Soedharmo
10	15	14	dependabot-preview[bot]
3	512	306	zbynek001
3	417	1	Ismael Hamed
1	5	5	Erik Følstad
1	5	19	Arjen Smits
1	27	1	Anton V. Ilyin
1	21	33	Igor
1	1	1	Cagatay YILDIZOGLU