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Showing posts with the label user groups

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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Nighthacking At Sevilla Java User Group

New Blog Post: Nighthacking At Sevilla Java User Group
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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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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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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: 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: 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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