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Showing posts with the label london

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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The birth of a new community

Topping off my mini-tour at the end of May, I was invited to Rotterdam to  present to a brand new community of developers.  I was really interested in attending because my experience with user groups is pretty much limited to the London Java Community , and I knew this would be different due to being a) across a wider range of technologies and b) shiny and new. It was hosted (rather awesomely) in a brewery, and until then I'd never given a presentation in a pub.  Frankly it's something I'm keen to do more of.  Due to a total technology fail on the part of all of us, we couldn't get the projector working with any of the various laptops.  However, with 30-odd techies, free wireless and slides available on Slideshare , we managed a novel and collaborative presentation approach, with people clustered around the laptops with the largest screens, and someone at each one valiantly keeping up with my quick pace through over 100 slides of stick-men drawings ...
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QCon London 2012

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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…. Firstly, me me me I presented the talk I previewed at Skillsmatter the previous week, something I was calling the User's Guide to the Disruptor, but actually turned out to be how-can-Trish-fill-95-slides-with-pictures-and-finish-in-under-40-minutes. The audience was different to the Skillsmatter event, not surprisingly.  What was surprising is that I expected people at the conference to be less aware of the Disruptor , and those who came to the Disruptor-only LJC event to have had more exposure to it.  It was a (pleasant) surprise to see how many of the standing-room-only audience had not only heard of the Disruptor but had read stuff about it (I always love it when people have read my blog), played with it an...
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What I Did On My Holidays

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And now, a post for my long-neglected, less technical readers. I took a week off in July to try and avoid that Oh My God I Missed Summer Again feeling. Granted, it's easy to get that in the UK even if you're not stuck in an office the entire time. Really this is just an excuse to post some photos on the blog. Monday Hopped on the bike and explored from Kensington to Westminster. Felt distinctly smug when I grabbed my lunch from Victoria amongst all the less fortunate people who had to go back to their offices. Tuesday Decided to dose up on Culture, and went to the National Gallery .  Last time I was there I was eight years old, and I distinctly remember admiring the frames more than the art. The rather marvellous  Artfinder makes up for the fact that you can't take photos inside the gallery - I can share most of the pieces that struck me when I was there. Wednesday Finally got around to embarking on one of the walks in Secret London .  I chose to d...
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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: Demystifying Memory Barriers

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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. Disclaimer: any errors in the explanation are completely my own, and no reflection on the implementation of the Disruptor or on the LMAX guys who actually do know about this stuff. What's the point? My main aim in this s...
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