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Showing posts from February, 2013

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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Staying Ahead of the Curve

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I had an interesting discussion last night at the LJC developer sessions, and it's a topic that comes up again and again: How do I stay ahead of the curve?  There are so many technologies out there, and more coming along, I can't even keep up with Java, let alone the other JVM languages, HTML5, JavaScript frameworks, NoSQL, Big Data.... argh! Technology, particularly development, seems to move at an ever-increasing pace.  Sure, the Internet makes it a lot easier for us to get access to information than in the Olden Days, when people probably had to read papers and books, and physically meet up to share knowledge, but that just makes the sheer volume of information even more overwhelming. So how do you keep on top of all those technologies? You don't. You can't.  If you devoted yourself to learning the same way you did at university (pfff, well, theoretically you devoted yourself to learning...), you could still never master every technology out there, and eve
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Upcoming Events (and Trisha Freaks Out A Bit)

My next few talks are where I finally start speaking about MongoDB .  After 4 months working for 10gen, I still feel completely under-qualified to speak with any authority on the subject.  It's very different joining a company with an established and growing product, to joining a very young company and being in on the development since practically day one.  But I've been working on designing the Brand New Java Driver, so that's what I'm going to talk about. At this stage, the new driver is still very much a prototype, and we have a lot of ideas to explore, so I'll be talking about things like design considerations, and the process of developing the driver, more than definitive guides on how to use it.  I've found working on a library very different to working on a platform or internal application. 19th Feb - London MUG: Into to the new Java driver 5th March - QCon: Tutorial (well, more like hack-session) on the new MongoDB Java driver 8th March - QCon
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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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