I’ve produced a very cut down version of the presentation I’ve been giving at a lot of conferences, giving a high level overview to the Disruptor. This serves as a quick intro to the concepts behind it.

On Sunday I gave my very first workshop on the Disruptor. The aim was to give people some hands-on coding experience using the syntax. Because time was limited (you can’t get people to build an entire application architecture in 2.5 hours) the example is somewhat contrived, and needs a big leap to make it into a proper application context. But the workshop should:

The “User’s Guide to the Disruptor” presentation I gave at QCon London is now available on the InfoQ site. This is the same presentation as the one I gave at Skillsmatter in March, but the questions are different. Plus since I’m winging it every time, I probably cover slightly different things or explain some stuff better / worse.

I was flattered to be interviewed for InfoQ at QCon London. It was a fun interview actually, and didn’t feel anything like the half an hour it actually took. In it, I get to talk about Agile at LMAX, the Disruptor (of course) and diversity in IT (again).

Here’s a video of my Open Conference session on the business benefits of open sourcing your software. Given that the conference was at a weekend and had a very intimate feel, I think I was a teeny bit more honest than I usually am. Enjoy.

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…

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.

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.

In theory, I am busy writing material for my upcoming speaking events, rather than writing terribly illuminating posts on my blog (see what I did there?). In actuality I am being lazy and have pretty much taken January off for a recharge.

In the spirit of doing something which ticks both the event-speaking and blogging boxes, this is a quick update on the conferences I’m confirmed for so far. Put the following dates in your diary - these are my first international solo speaking events:

At JAX London Mike and I presented “Understanding the Disruptor - A Beginner’s Guide to Hardcore Concurrency”. This is the session we initially previewed to the London Java Community a few weeks earlier. The content is the same, but the feel of the presentation was quite different to us - the venue for the LJC event was more intimate, and it was easier to interact with the audience. At JAX, we were up on stage, which was pretty cool actually, but meant that it felt more like a lecture and it was less easy to connect with the audience.

Saturday was, hopefully, my last conference of the year. My lucky readers should start to see some posts which are not simply me gushing about another opportunity to hang out with awesome people and learn about interesting “stuff”.

Last Tuesday Mike and I unveiled our brand shiny new presentation: Understanding the Disruptor, a Beginner’s Guide to Hardcore Concurrency. This was a preview of the talk we’ll be doing at JAX London on the 2nd November. A video of the session is available, as are the slides. I promise not to say “so” anywhere near as many times when I repeat my performance at JAX (is there anything more painful than watching yourself on video?

Having been back in London for a few days I’ve had some time to digest the madness that was last week.

My lasting impression of JavaOne is almost entirely positive. Granted, it was my first major conference, so maybe I’m just not jaded yet. But let me tell you what I loved about it (yes, I did cover some of these in my last post):

Here’s a photo of me representing LMAX as I pick up the Duke Award we won for the Disruptor (Thanks to Martijn for taking the photo)

So I’ve been at JavaOne for the better part of three days, it’s time to record some of my observations so far:

Martin recently announced version 2.0 of the Disruptor - basically there have been so many changes since we first open-sourced it that it’s time to mark that officially. His post goes over all the changes, the aim of this article is to attempt to translate my previous blog posts into new-world-speak, since it’s going to take a long time to re-write each of them all over again. Now I see the disadvantage of hand-drawing everything.

My recent slow-down in posting is because I’ve been trying to write a post explaining memory barriers and their applicability in the Disruptor. The problem is, no matter how much I read and no matter how many times I ask the ever-patient Martin and Mike questions trying to clarify some point, I just don’t intuitively grasp the subject. I guess I don’t have the deep background knowledge required to fully understand.

So, rather than make an idiot of myself trying to explain something I don’t really get, I’m going to try and cover, at an abstract / massive-simplification level, what I do understand in the area. Martin has written a post going into memory barriers in some detail, so hopefully I can get away with skimming the subject.

We mention the phrase Mechanical Sympathy quite a lot, in fact it’s even Martin’s blog title. It’s about understanding how the underlying hardware operates and programming in a way that works with that, not against it.

We get a number of comments and questions about the mysterious cache line padding in the RingBuffer, and I referred to it in the last post. Since this lends itself to pretty pictures, it’s the next thing I thought I would tackle.

Martin Fowler has written a really good article describing not only the Disruptor, but also how it fits into the architecture at LMAX. This gives some of the context that has been missing so far, but the most frequently asked question is still “What is the Disruptor?”.

I’m working up to answering that. I’m currently on question number two: “Why is it so fast?”.

So now I’ve covered the ring buffer itself, reading from it and writing to it.

Logically the next thing to do is to wire everything up together.

I talked about multiple producers - they have the producer barrier to keep them in order and under control. I’ve talked about consumers in a simple situation. Multiple consumers can get a little more involved. We’ve done some clever stuff to allow the consumers to be dependent on each other and the ring buffer. Like a lot of applications, we have a pipeline of things that need to happen before we can actually get on with the business logic - for example, we need to make sure the messages have been journalled to disk before we can do anything.

The Disruptor paper and the performance tests cover some basic configurations that you might want. I’m going to go over the most interesting one, mostly because I needed the practice with the graphics tablet.

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.

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.

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 pattern, the clever bit about the Disruptor is controlling access to it.