reactive messaging - producing messages continuosly

[Vincenzo D'Amore]

Hi All,

I hope this is the right forum where talk about smallrye reactive messaging.

I wrote a sample where try to understand how to produce messages continuosly.

So I have a method that produces continuosly messages:

    @Outgoing("from-producer-to-processor")
    public Multi<ClassA> periodicallySendMessage() {

        return Multi.createFrom()
                .ticks()
                .every(Duration.ofMillis(50))
                .onItem().transform(t -> new ClassA("Hello " + t))
                .onFailure(mm -> {
                    log.info("Producer NOT EMITTING");
                    return true;
                })
                .retry()
                .withBackOff(Duration.ofSeconds(1), Duration.ofSeconds(10))
                .indefinitely()
                .onItem()
                .invoke(msg -> log.info("Producer emitting " + msg));
    }

What I realized is that if a failure happens, for example if the method that consumes message through the @Incoming  annotation is slow, the failure is rised but the ticks starts again from 1, am I right?

I have also noticed that the failure is raised only when a considerable amount of messages are sent (at least 256). I suppose this is the default behaviour, given that the default buffer size is 256. But even trying to change the buffer size, I was unable to control the number of messages sent, before a failure (caused by a slow consumer) is raised.

Best regards,

Vincenzo

[clement escoffier]

Hello,

You cannot constraint time, so the back pressure protocol cannot be used when using ticks. So, you need:

Multi.createFrom().ticks().every(Duration.ofMillis(50)).onOverflow().drop()

It will drop the ticks if the subscriber cannot handle the load. 

Clement

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[Vincenzo D'Amore]

Hi Clement,

thanks for answering.

What about removing the ticks() part with a generator? Could you help me out with that?

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Vincenzo D'Amore

[clement escoffier]

A generator will help as we will stop calling it when we do not have requests.

Clement

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