concurrent programming using the...

Concurrent Programming Using The Disruptor

Trisha Gee, Developer at LMAX@trisha_gee

mechanitis.blogspot.com

Thursday, 24 May 12

The Disruptor?

Thursday, 24 May 12

What I’m covering

• Overview of the Disruptor

• Create your own!

• Turn it up to Eleven

• Q&A

Thursday, 24 May 12

What is it?

• Data structure and work flow with no contention.

• Very fast message passing.

• Allows you to go truly parallel.

Thursday, 24 May 12

So...?

Thursday, 24 May 12

The Magic RingBuffer

Thursday, 24 May 12

Creating a RingBuffer

final RingBuffer<SimpleEvent> ringBuffer = new RingBuffer<SimpleEvent>(SimpleEvent.EVENT_FACTORY, RING_BUFFER_SIZE);

Thursday, 24 May 12

The Events are Buckets

Thursday, 24 May 12

Great! I want one!

public class SimpleEvent { public static final EventFactory<SimpleEvent> EVENT_FACTORY = new SimpleEventFactory();

private volatile String value;

private static class SimpleEventFactory implements EventFactory<SimpleEvent> { @Override public SimpleEvent newInstance() { return new SimpleEvent(); } } }

Thursday, 24 May 12

I’ve got a RingBuffer!

• Erm.... how do I poke things into it?

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The Publisher

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What do I do?

SimpleEventTranslator translator = new SimpleEventTranslator();

EventPublisher<SimpleEvent> publisher = new EventPublisher<SimpleEvent>(ringBuffer);

// poke your translator here// ...and when you’re done...publisher.publishEvent(translator);

public class SimpleEventTranslator implements EventTranslator<SimpleEvent>

Thursday, 24 May 12

...so now I want to read

• The Disruptor provides nice batching behaviour for free

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BatchEventProcessor

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...and all you need is...

public class SimpleEventHandler implements EventHandler<SimpleEvent> { @Override public void onEvent(final SimpleEvent event, final long sequence, final boolean endOfBatch) throws Exception { // do stuff } }

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Shiny. So what?

Thursday, 24 May 12

Let’s go parallel

Thursday, 24 May 12

And now for something different...

Thursday, 24 May 12

Remember Henry Ford?

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Thursday, 24 May 12

Complex workflow...

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What on Earth has this got to do with RingBuffers?!

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Thursday, 24 May 12

Don’t wrap the buffer!

ringBuffer.setGatingSequences(finalEventProcessor.getSequence());

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Caveats

Thursday, 24 May 12

Is that it?

• Wait and claim strategies

• Batch publishing

• Multiple publishers

• Different EventHandlers

• The Wizard

• You don’t even need a RingBuffer...

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You get...

• A framework the encourages you to model your domain

• The ability to run in parallel but single-threaded

• Nice, simple Java

• Reliable ordering

• ...and it can be very fast

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More Information

• Google Code Site, including Wikihttp://code.google.com/p/disruptor/

• Blogs, e.g. mine: mechanitis.blogspot.com

• Presentations

• Google Group

Thursday, 24 May 12

http://code.google.com/p/disruptor/

http://code.google.com/p/disruptor/

Q&A

Thursday, 24 May 12

WorkerPool

Thursday, 24 May 12

AggregateEventHandler

Thursday, 24 May 12

WaitStrategies

• BlockingWaitStrategy

• BusySpinWaitStrategy

• SleepingWaitStrategy

• YieldingWaitStrategy

Thursday, 24 May 12

ClaimStrategies

• SingleThreadedClaimStrategy

• MultiThreadedClaimStrategy

• MultiThreadedLowContentionClaimStrategy

Thursday, 24 May 12

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