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Showing posts from February, 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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Why the customer isn't always right

Last week I went to get my hair cut (yes, sorry, this is a story about hair).  I had thought long and hard about what I wanted.  I researched, checked styles online, and bought a magazine so I could show my hairdresser exactly what I was after and there would be no confusion.  I was determined I would not be spending that ridiculous amount of money on something I was not going to be happy with.  I was even bold enough to ask for some changes to it at the end, which I have never ever had the courage to do before. He did an excellent job.  It was almost exactly what I had asked for, with some variations to account for my particular hair type.  It was a very cute hair style that suited me.  But I had a niggling doubt. A few days later, that niggle was a certainty.  It wasn't what I wanted. However, it was what I had asked for. Being English, the thought of going back and telling him I wasn't happy with it was horrifying.  Especially sinc...
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Location: London, UK
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Upcoming speaking events

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: 7th March - QCon London - Concurrent Programming Using The Disruptor  (sadly I can't stay for the whole conference as it clashes with the only holiday I had booked for 2012). 23rd May - GOTO Copenhagen - Concurrent Programming Using The Disruptor  & War Stories. 25-26th May - GOTO Amsterdam - Concurrent Programming Using The Disruptor . The presentation will be more of a user's guide to the Disruptor than anything we've done before.  An hour isn't a lot of time to c...
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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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