Akka.DistributedData: port `VectorClock` performance optimizations to `VersionVector` and similar types

[Aaronontheweb]

Version: v1.4.18

The performance optimizations we applied to #4952 for VectorClock could also be applied to the VersionVector type in the Akka.DistributedData library and many of the CRDT types contained within. That way, we could improve overall CRDT in-memory performance - especially comparison to other versions of the same object and eventually merging of like-kinded objects together.

[andyfurnival]

@Aaronontheweb could this explain why I get high memory usage when using DData? When I start a 7 node cluster up, and I have a 5mb ddata file, no other activities happening in the cluster except internal gossip, I quickly run out of memory (512mb container limit) with lots of exceptions like this below.

  Akka.DistributedData.Durable.LoadFailedException: failed to load durable distributed-data
   ---> System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown.
     at Akka.Actor.Address.CreateLazyToString()
     at Akka.DistributedData.Serialization.SerializationSupport.AddressFromProto(Address address)
     at Akka.DistributedData.Serialization.SerializationSupport.UniqueAddressFromProto(UniqueAddress address)
     at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
     at Akka.DistributedData.Serialization.SerializationSupport.VersionVectorFromProto(VersionVector versionVector)
     at System.Linq.Enumerable.SelectIListIterator`2.MoveNext()
     at System.Linq.Enumerable.ZipIterator[TFirst,TSecond,TResult](IEnumerable`1 first, IEnumerable`1 second, Func`3 resultSelector)+MoveNext()
     at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()
     at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 items, MutationInput origin, KeyCollisionBehavior collisionBehavior)
     at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 pairs, Boolean avoidToHashMap)
     at Akka.DistributedData.Serialization.ReplicatedDataSerializer.FromProto(ORSet orset)
     at Akka.Serialization.Serialization.Deserialize(Byte[] bytes, Int32 serializerId, String manifest)
     at Akka.DistributedData.Serialization.SerializationSupport.OtherMessageFromProto(OtherMessage other)
     at Akka.DistributedData.Serialization.ReplicatorMessageSerializer.DurableDataEnvelopeFromBinary(Byte[] bytes)
     at Akka.DistributedData.LightningDB.LmdbDurableStore.b__20_1(ValueTuple`2 x, Int32 i)
     at System.Linq.Enumerable.SelectIterator[TSource,TResult](IEnumerable`1 source, Func`3 selector)+MoveNext()
     at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 items, MutationInput origin, KeyCollisionBehavior collisionBehavior)
     at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 pairs, Boolean avoidToHashMap)
     at Akka.DistributedData.LightningDB.LmdbDurableStore.b__20_0(LoadAll loadAll)
     --- End of inner exception stack trace ---
     at Akka.DistributedData.LightningDB.LmdbDurableStore.b__20_0(LoadAll loadAll)
     at lambda_method(Closure , Object , Action`1 )
     at Akka.Actor.ReceiveActor.ExecutePartialMessageHandler(Object message, PartialAction`1 partialAction)
     at Akka.Actor.UntypedActor.Receive(Object message)
     at Akka.Actor.ActorBase.AroundReceive(Receive receive, Object message)
     at Akka.Actor.ActorCell.ReceiveMessage(Object message)
     at Phobos.Actor.PhobosActorCell.ProcessMsgWithTrace(Object underlyingMsg, ISpanContext context, IScope scope, Boolean followFromActiveSpan)
     at Phobos.Actor.PhobosActorCell.ReceiveMessage(Object message)
     at Akka.Actor.ActorCell.Invoke(Envelope envelope) 

[Aaronontheweb]

@andyfurnival yep, absolutely - we're planning on doing a v1.4.19 release today but we can tack on a v1.4.20 release shortly thereafter with this fixed. Most of the memory overhead actually comes from the KeyValuePair<TKey,TValue>.Equals implementation, amazingly.

[Aaronontheweb]

Began work on this #4990

[Aaronontheweb]

This is completed.