TestScheduler has to be manually advanced
I'm getting the error "When using remember-entities the shard id extractor must handle ShardRegion.StartEntity(id)" even though the StartEntity is handled in the message extractor. Am I missing something? Hope someone will have time to answer me ;-)
public class CustomMessageExtractor : HashCodeMessageExtractor
{
public CustomMessageExtractor() : base(maxNumberOfShards: 100) { }
public override string EntityId(object message)
{
return message switch
{
NotificationActor.Subscribe sub => sub.ConnectionId,
ShardRegion.StartEntity start => start.EntityId,
_ => null
};
}
public override string ShardId(object message)
{
if (message is NotificationActor.Subscribe sub)
{
return sub.EventName;
}
return null;
}
}
I think the example in "Remembering entities" is wrong
https://getakka.net/articles/clustering/cluster-sharding.html
string ShardId(object message) from that class. I wonder if it should be sealed...
StartEntity being handled, so users can see the difference
Is it possible to broadcast a message to all entities in the same shard? For instance, I want to send one message to all entities that live in the shard
Ummm I feel like there's a way to do that, let me think
.... I mean, I have no clue whether this works or would do what you need, but you could try an
ActorSelectionlike/system/sharding/customer/customerupdated/*<-- Maybe it should be /user/ but I think it's /system/
Thanks a lot @to11mtm
It is no longer needed because I went in a different direction but it is worth to try :-)
One more question, is it possible to configure the shard actor's supervision or even better tell akka sharding to use a custom shard actor?
Hey everyone. I started up a project using Akka.NET after a few years of doing the tutorial and some small projects. Right now, it's mostly just pulling stock data and inserting into a Timescale database. Probably a pretty common use case :)
Anyways, I was wondering what the recommended approach might be to creating many singleton actors. A common case will be a simple ETL style pipeline. So, some sort of coordinator/conductor actors specifying what to download and when, then a extractor actor, possibly an actor to handle api rate limiting, then a loader actor to insert the data into the database.
I have a few of these created, but right now I just have everything initialized in the main method and passed through the constructors, which is pretty ugly, so I want to fix these before I create too many more of these pipelines.
A few (well, lots of) questions:
- It seems like some DI packages specifically for Akka.NET recently came out. Guessing I should be using this?
- Should I create a conductor (Is there a better name for this?) actor for each pipeline? And should the messages flow through the pipeline actors directly, or should they all be relayed through the conductor? It seems like could possibly make error handling easier, but message routing might be a little more awkward.
- Should I define the pipelines in code, or in the database and create them at runtime?
- For situations where I am loading data into a table, I will have a loader for each table working serially. Should I use async/await on the database call, or PipeTo? Since I want to do this serially (at least for now, since I am just using a single staging table truncated between requests and repopulated with postgres copy command), I'm thinking I should use async/await.
- How much do I have to worry about message size if I am using a single machine on my home server? (Ryzen 3600 6 cores, 12 threads, 32 GB ECC ram, SDDs). Right now, I am putting entire files/streams in messages to load with the copy command, which is a efficient way to load data into postgres.
Sorry for the wall of text of questions.
12 replies
Akka.FSharp still a thing?
We're starting to look into potentially moving our akka estate onto akka clustering. The question has been raised as to whether we should do one large cluster of all of our microservices (Probably would be ~50 nodes) or to have multiple small clusters. Does the cost of adding a new node into the cluster increase with the size of the cluster? Are there any stats that we could look at surrounding how much resources gossiping takes against the size of the cluster?
Our estate is a lot of microservices that are very distinct and a lot have their own bounded contexts so not all of them necessarily talk to any other service, for these we would be looking active/passive or to have sharding depending on what that particular service is doing. Does anyone have any opinions or experience with something like this? Any advice welcomed!
9 replies
await in any class's code it's variables have to be declared as volatileto avoid the problem you describe. The short answer is no, you should not need volatile keyword unless your message handling code for some reason requires it.
[akka://AspNetDemo/system/akka.persistence.snapshot-store.local#1960469910]: Akka.Actor.ActorInitializationException: Exception during creation
---> System.TypeLoadException: Error while creating actor instance of type Akka.Persistence.Snapshot.LocalSnapshotStore with 0 args: ()
---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
---> System.MissingMethodException: Method not found: 'Akka.Pattern.CircuitBreaker Akka.Pattern.CircuitBreaker.Create(Int32, System.TimeSpan, System.TimeSpan)'.
at Akka.Persistence.Snapshot.SnapshotStore..ctor()
at Akka.Persistence.Snapshot.LocalSnapshotStore..ctor()