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Showing posts from December, 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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Devoxx: The Problem with Women - A Technical Approach

As well as talking about, you know, actual work-type-stuff , I was encouraged to give my "Technical Approach to Women" presentation at Devoxx.  This went so well at JavaOne that I thought it would be difficult to top.  Also, I wasn't convinced it would work at Devoxx, because the theatres are not well suited to audience participation - the seats are warm and comfy, the room is dark, the speaker is on stage in front of a massive screen.... I was incredibly impressed with the audience.  There were literally hundreds of people, most of them men.  To me, it proved once again that the men in this industry are determined to "fix" this problem of gender imbalance.  And they're happy to extend that to improving diversity as a whole, once you highlight the bigger problem.  It says to me that this is not naturally a misogynistic industry, where you have to fight against the boys club to get anywhere.  It says to me that we are all in this together.  After all, in th
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Agile++: When Agile Goes Well

If you see anything about LMAX - the Disruptor, Continuous Delivery, or even the selection criteria for hiring developers, you'll see that LMAX is pretty keen on Agile .  However, no-one's documented the Agile process there, as far as I know.  Although I personally had it on my todo list, I never had the motivation, the hook to do it.  And I realised eventually that's because I'm not sure it's a process that would work very well for another team, in another company, working in another business. The agile process followed at LMAX is one that works for the individuals and the organisation there.  And that's because they do one thing very well - they regularly examine the issues faced and adapt the process to try and combat them.  It's an agile process that's, well, very agile - it's constantly changing.  Documenting it would only represent a single snapshot in time that would be out of date almost as soon as the next retrospective comes along.
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Webinar: Processing High Volume Data Feeds with MongoDB

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Hot on the heels of my very first MongoDB webinar,  I was... encouraged... to do another.  Here at 10gen we've been running a series of webinars around using MongoDB in the financial services domain.  Yesterday was the last in the series, and was presented in association with C24  - John Davies , their CTO, did most of the talking, and demonstrated their product for automatically turning financial messages from one format into another. video platform video management video solutions video player (Slides and webinar available here - and you're not going deaf, the sound doesn't start until about 3:44 into the video) It was a fun webinar to do, actually - I didn't know anything about C24's iO tool, so I learnt quite a lot as I watched John navigate the demo.  My background in trying to debug raw FIX messages probably skewed my questions, I was definitely more interested in how to use it as a developer and what it could give me if I were doing production su
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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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