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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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Effective Sketches

On Thursday I was at Simon Brown's Effective Sketches session at Skillsmatter .  Just because my pictures are pretty awesome doesn't mean there's no opportunity for continuous learning. The points Simon made in the session really made sense to me, and I wish I could have had something like that as a primer when they taught us UML at university.  Without the context of what the diagrams were supposed to mean, to convey, all the boxes and lines made no sense to me back then.  I'm still not a fan of large chunks of UML because I think the convention sometimes gets in the way of real meaning. My take-away points were: Don't try and squidge everything onto a single diagram.  The reason lots of different flavours of architecture diagrams exist (e.g. logical view , infrastructure view , etc) is because you have different audiences for each of the diagrams and different things that are important when you're looking at it from one particular angle. One diagram yo...
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Certified Scrum Master

Hmm. I have been so busy trying to think of "good" things to write here, and not having the time to actually write, that I see it's been 6 months since the last post. If anyone is still out there though, I need help. I need a good Certified Scrum Master course in New York or London, preferably in April or May. Any suggestions? The one I wanted to go on was vetoed and now I find it's not running in NY again until Autumn. PS Do you think it would be inappropriate to use the term "Scrum Mistress" on my CV?
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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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