CODEWITHSUNDEEP
javaakkaactor
ses
ses

Reputation: 13342

Akka Actor cleans its state unexpectedly

I have this actor that is involved in parallel-word-count-calculation.

It has a state:

private Map<String, Integer> wordCountMap = new HashMap<String, Integer>();

As it received WordCountMapMessage message, it changed the state to have 9 elements in it:

{over=1, fell=1, fox=1, quick=1, tried=1, brown=1, lazy=1, dog=2, jump=1}

(there is main class for that - you can see outputs if you launch it)

Then when it receives ResultMessage, then wordCountMap is empty.

Q: How come, all of the sudden it has empty map/state?

Is that possible that Actor is re-initializing its state somehow with no message passed?

-- Update: If I ovveride methods preStart in AggregateWordCountActor, then I can see output like this:

pre-start pre-start pre-start pre-start pre-start

It seems it starts 5 times ! But it does not launch any preRestart

Upvotes: 0

Views: 136

Answers (2)

cmbaxter
cmbaxter

Reputation: 35443

Your issue seems to be that you are using a RoundRobinPool for each child actor in the Master actor. Because your child actors are stateful, when the request comes in to request the current state, it goes to a different actor instance then the one that received the request to process the words (via the round robin routing logic). Remove the routers from your child actor creation in the Master actor and your code should work.

Upvotes: 1

chemikadze
chemikadze

Reputation: 815

It seems it starts 5 times ! But it does not launch any preRestart

That's because you are using withRouter(new RoundRobinPool(5)) -- it creates 5 actors that will receive messages in round-robin fashion.

Problem is that you are receiving state of different actor than have completed computation: actors that will receive WordCountMapMessage and ResultMessage are not the same.

Upvotes: 1

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