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Showing posts from January, 2014

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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Sevilla MUG, first event

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Last night was the inaugural meeting of the Sevilla MongoDN User Group.  An event organised with just over 48 hours notice, in a city where I don't speak the language and where even my best-connected contacts aren't sure they're fully plugged in to the tech scene. I'll admit, I had some reservations: a lightning talk? Will people come all that way for beer and 15 minutes of presentation? in English? Whilst I'm desperately learning Spanish to get closer to presenting in Spanish, at this point I'm just not ready and have to hope people want to listen to me ramble in a foreign language a MUG? Are people interested in joining a group that's solely focussed on one technology, a technology that might not have adoption here or even interest? two days notice?  Are you kidding?  I know people here like to figure out their plans at the last minute, but surely this is shooting ourselves in the foot before we even start. And then last night...  The peop...
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Introduction to MongoDB and Big Data

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I wrote an article for the latest edition of Java Magazine which is an introduction to MongoDB for Java developers, and a nod to why it's good in the "Big Data" space. Look inside > MongoDB and Big Data
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Why is it News when a woman becomes CEO?

I'm pleased to see that GM has hired the "best person for the job" as their new CEO  - that does seem like a good idea.  I'm happy her gender did not get in the way.  What makes me uncomfortable is the international news coverage of the decision of this large manufacturer to hire a woman as their CEO - if she were a man (and/or black/gay/disabled) would the headline read "The camera loves her. So do employees."? But at the root of that is probably the thing I'm most unhappy about.  What I'm not happy about is that it is 2014, halfway through the second decade of the 21st century, and she's the first woman CEO of a car manufacturer. I worked at Ford Motor Company as an undergraduate and, later, a graduate.  I basically did my apprenticeship there. I know that over fifteen years ago they were hiring graduates from different disciplines (men and women), they had a women-in-leadership programme (or probably several, as I was only involved in the...
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Goodbye 2013, you were good to me...

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Well, if I thought 2012 was the fastest disappearing year on record , that record was smashed into the ground by 2013.  What a year!  And because I didn't manage to write this on time to publish elsewhere, I can do a more personal reflection of the year here on my very own blog. Apparently, reading over last year's article, I had goals for 2013: Get more involved in schools/mentoring. Yeah... That didn't happen. I don't think I even made a single Meet a Mentor event this year, which is an excellent, really lightweight way of mentoring in London, and I'm sorry I was unable to participate. Contribute to a major release of the MongoDB Java Driver. Well, I contributed... but it's still not ready for release yet. Give a keynote at an international conference. Nope, didn't manage this either! But I did keynote at the LJC Open Conference again. ...and more of the same from this year : presentations, user groups, blogging, workshops. Well, this I did manage....
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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 hea...
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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...
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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 n...
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