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Showing posts from March, 2012

This Blog Has Moved!

Right, so yes, five years ago I moved to github pages, and never bothered to redirect any of these pages there. Now I've moved on from there, and... Finally I am using my real domain, trishagee.com . My blog is now at trishagee.com/blog .  See you there!
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QCon London 2012

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I'm late with my write-up of QCon , and what's worse, it will be partial - "sadly" I was in Lanzarote on a training week with the running club from the Thursday (8th) so I missed most of it.  A sacrifice I had to make for 7 days in the sunshine…. Firstly, me me me I presented the talk I previewed at Skillsmatter the previous week, something I was calling the User's Guide to the Disruptor, but actually turned out to be how-can-Trish-fill-95-slides-with-pictures-and-finish-in-under-40-minutes. The audience was different to the Skillsmatter event, not surprisingly.  What was surprising is that I expected people at the conference to be less aware of the Disruptor , and those who came to the Disruptor-only LJC event to have had more exposure to it.  It was a (pleasant) surprise to see how many of the standing-room-only audience had not only heard of the Disruptor but had read stuff about it (I always love it when people have read my blog), played with it an
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Java Magazine: Intro to the Disruptor Part One

This month's Java Magazine  features an article by yours truly, which is yet another intro to the Disruptor.  It's basically a summary of the stuff I've written in this blog, updated for version 2.7 - so the names of the classes should be up to date and the responsibilities follow the simplified pattern we use now.  If you were looking for an more recent version of my introduction blog posts, this article gives a reasonable overview. This is intended as part one of a series, as it's a basic and high-level view with no code examples.  In fact, it probably could be used to document the C# version as well as the Java version, although I haven't taken a look at that for a while.  Next, I would like to give some more code examples of how you use it - as always, any suggestions welcome.
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New Disruptor Presentation Unveiled to the LJC!

A few weeks ago, I presented my new "User's Guide to the Disruptor" talk to the London Java Community .  Since it was very kindly hosted at Skillsmatter, there is a video of the presentation available, and the slides are below. Concurrent Programming Using the Disruptor View more presentations from Trisha Gee The presentation is a little different to the ones we've done before.  Previously we've gone into how it works and why it's fast.  This time I wanted to step back a little from the internals and show how real developers might actually use it.  The example is somewhat contrived, but the idea is to give some hints on how to break your problem down into something that will work with a Disruptor at the heart of it. I thought the event went really well.  It was a tiny bit completely intimidating, as there were no lightning talks and I was the only attraction.  Seeing over a hundred people turn up after work, before beer, to hear you talk is a hu
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Popular posts from this blog

Dissecting the Disruptor: What's so special about a ring buffer?

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Recently we open sourced the LMAX Disruptor , the key to what makes our exchange so fast.  Why did we open source it?  Well, we've realised that conventional wisdom around high performance programming is... a bit wrong. We've come up with a better, faster way to share data between threads, and it would be selfish not to share it with the world.  Plus it makes us look dead clever. On the site you can download a technical article explaining what the Disruptor is and why it's so clever and fast.  I even get a writing credit on it, which is gratifying when all I really did is insert commas and re-phrase sentences I didn't understand. However I find the whole thing a bit much to digest all at once, so I'm going to explain it in smaller pieces, as suits my  NADD audience. First up - the ring buffer.  Initially I was under the impression the Disruptor was just the ring buffer.  But I've come to realise that while this data structure is at the heart of the patte
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Dissecting the Disruptor: Writing to the ring buffer

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This is the missing piece in the end-to-end view of the Disruptor.  Brace yourselves, it's quite long.  But I decided to keep it in a single blog so you could have the context in one place. The important areas are: not wrapping the ring; informing the consumers; batching for producers; and how multiple producers work. ProducerBarriers The Disruptor code has interfaces and helper classes for the Consumer s, but there's no interface for your producer, the thing that writes to the ring buffer.  That's because nothing else needs to access your producer, only you need to know about it.  However, like the consuming side, a ProducerBarrier is created by the ring buffer and your producer will use this to write to it. Writing to the ring buffer involves a two-phase commit.  First, your producer has to claim the next slot on the buffer.  Then, when the producer has finished writing to the slot, it will call commit on the ProducerBarrier . So let's look at the first bi
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Dissecting the Disruptor: How do I read from the ring buffer?

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The next in the series of understanding the Disruptor pattern developed at LMAX . After the last post we all understand ring buffers and how awesome they are.  Unfortunately for you, I have not said anything about how to actually populate them or read from them when you're using the Disruptor. ConsumerBarriers and Consumers I'm going to approach this slightly backwards, because it's probably easier to understand in the long run.  Assuming that some magic has populated it: how do you read something from the ring buffer? (OK, I'm starting to regret using Paint/ Gimp .  Although it's an excellent excuse to purchase a graphics tablet if I do continue down this road.  Also UML gurus are probably cursing my name right now.) Your Consumer is the thread that wants to get something off the buffer.  It has access to a ConsumerBarrier , which is created by the RingBuffer and interacts with it on behalf of the Consumer .  While the ring buffer obviously needs a se
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