Akka.Streams.TestKit 1.4.21

Maintenance Release for Akka.NET 1.4** Akka.NET v1.4.21 is a significant release that includes major performance improvements, bug fixes, and a major update to the [Akka.DependencyInjection NuGet package](https://getakka.net/articles/actors/dependency-injection.html). Performance Improvements** Akka.NET v1.4.21 includes some major performance fixes and improvements: [`Ask` is now ~10% faster](https://github.com/akkadotnet/akka.net/pull/5051) [`MurmurHash` is 33% faster and allocates 0 memory](https://github.com/akkadotnet/akka.net/pull/5028) - used _heavily_ in DData, Cluster Sharding, and Consistent Hash Routers `ActorPath.Parse` went from 1672 ns/op to 527 ns/op - a 68% improvement in throughput and a 50% reduction in memory. See [#5039](https://github.com/akkadotnet/akka.net/pull/5039) and [#5068](https://github.com/akkadotnet/akka.net/pull/5068). [Akka.Remote: remove `ActorPath.ToString` call from `ResolveActorRefWithLocalAddress`](https://github.com/akkadotnet/akka.net/pull/5034) Important**: [Revert `ThreadPool.SetMinThreads(0,0)`](https://github.com/akkadotnet/akka.net/pull/5059) - based on the input from users on "[Akka.NET v1.4.19: ChannelExecutor performance data](https://github.com/akkadotnet/akka.net/discussions/4983)" Our observed performance numbers for Akka.Remote show a significant increase in performance for v1.4.21 over v1.4.20: Before* ``` PS> dotnet run -c Release --framework netcoreapp3.1 OSVersion: Microsoft Windows NT 6.2.9200.0 ProcessorCount: 16 ClockSpeed: 0 MHZ Actor Count: 32 Messages sent/received per client: 200000 (2e5) Is Server GC: True Thread count: 109 Num clients, Total [msg], Msgs/sec, Total [ms] 1, 200000, 113379, 1764.56 5, 1000000, 186429, 5364.05 10, 2000000, 185340, 10791.11 15, 3000000, 183218, 16374.06 20, 4000000, 179824, 22244.63 25, 5000000, 182716, 27365.89 30, 6000000, 182039, 32960.61 ``` After* ``` PS> dotnet run -c Release --framework netcoreapp3.1 OSVersion: Microsoft Windows NT 6.2.9200.0 ProcessorCount: 16 ClockSpeed: 0 MHZ Actor Count: 32 Messages sent/received per client: 200000 (2e5) Is Server GC: True Thread count: 111 Num clients, Total [msg], Msgs/sec, Total [ms] 1, 200000, 109770, 1822.14 5, 1000000, 192902, 5184.79 10, 2000000, 191663, 10435.53 15, 3000000, 191339, 15679.11 20, 4000000, 192725, 20755.78 25, 5000000, 189754, 26350.14 30, 6000000, 189772, 31617.20 ``` > N.B. these after numbers don't benefit from the performance benefits we observed in v1.4.20 when we invoked `ThreadPool.SetMinThreads(0,0)`, which makes them even more impressive. Akka.DependencyInjection Updates** We had one major issue we implemented in v1.4.21 for Akka.DependencyInjection: [Abstraction of `ServiceProvider`, Improving Akka.DependencyInjection ](https://github.com/akkadotnet/akka.net/pull/4814) What this change did was: Deprecate the `Akka.DependencyInjection.ServiceProvider` class in favor of the `Akka.DependencyInjection.DependencyResolver` class - to avoid namespace collision with Microsoft.Extensions.DependencyInjection.ServiceProvider; Deprecates the `Akka.DependencyInjection.ServiceProviderSetup` class in favor of the `Akka.DependencyInjection.DependencyResolverSetup` class for consistency reasons; `Akka.DependencyInjection.DependencyResolver` now takes an input of type [`IDependencyResolver`](https://getakka.net/api/Akka.DependencyInjection.IDependencyResolver.html), which allows users to abstract away the `IServiceProvider` and mock / replace it during unit testing; and Added some non-generic `Props` methods for dynamically spawning actors via DI. All of these changes are backwards-compatible with v1.4.20 and earlier - and the deprecation warnings will appear in your code when you upgrade. If you run into any [issues upgrading to Akka.DependencyInjection v1.4.21 please reply on this thread](https://github.com/akkadotnet/akka.net/discussions/5070)! Other Changes and Fixes** [Akka.Streams: A couple of fixes affecting the `FileSubscriber`](https://github.com/akkadotnet/akka.net/pull/5035) [Akka.DistributedData: memory leak when recovering events from LMDB data store](https://github.com/akkadotnet/akka.net/issues/5022) [Akka.DistributedData: port `VectorClock` performance optimizations to `VersionVector` and similar types](https://github.com/akkadotnet/akka.net/issues/4956) To see the [full set of fixes in Akka.NET v1.4.21, please see the milestone on Github](https://github.com/akkadotnet/akka.net/milestone/51). | COMMITS | LOC+ | LOC- | AUTHOR | | --- | --- | --- | --- | | 5 | 34 | 24 | Aaron Stannard | | 4 | 196 | 77 | Gregorius Soedharmo | | 3 | 3 | 3 | dependabot[bot] | | 1 | 2 | 2 | Wessel Kranenborg | | 1 | 1 | 1 | Martijn Schoemaker |