Solution to slow consumer(eventProcessor) issue in LMAX Disruptor pattern

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While using the disruptor, there may be a consumer(s) that is lagging behind, and because of that slow consumer, the whole application is affected.

Keeping in mind that every producer(Publisher) and consumer(EventProcessor) is running on a single thread each, what can be the solution to the slow consumer problem?

Can we use multiple threads on a single consumer? If not, what is a better alternative?

disruptor-pattern consumer
3 Answers

Use a set of identical eventHandlers. To avoid more than 1 eventHandler acting upon a single event, I use the following approach.

Create a thread pool of size Number of cores in the system

Executor executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors()); // a thread pool to which we can assign tasks

Then create a handler array

 HttpEventHandler [] handlers = new HttpEventHandler[Runtime.getRuntime().availableProcessors()];

for(int i = 0; i<Runtime.getRuntime().availableProcessors();i++){
    handlers[i] = new HttpEventHandler(i);
}

disruptor.handleEventsWith(handlers);

In the EventHandler

public void onEvent(HttpEvent event, long sequence, boolean endOfBatch) throws InterruptedException
{
    if( sequence % Runtime.getRuntime().availableProcessors()==id){

        System.out.println("-----On event Triggered on thread "+Thread.currentThread().getName()+" on sequence "+sequence+" -----");
        //your event handler logic
}
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