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Showing posts from October, 2011

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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On The Similarities Between Girls And Aliens

I discovered, through the power of the search words that lead to my blog, that there was an incident at JavaOne that once again opens the can of worms that is Sexism In IT. This Makes Me Sad.  I had a really positive experience at JavaOne.  In fact, I would say it was the one conference I've been to in the last 12 months where I felt like my gender wasn't a problem - I even got away with wearing hotpants (tweed is business-casual, right??) without being mistaken for anything other than a developer. I know incidents like this cause a lot of tension, and I want to explore why.  Get ready for some gross generalisations: women get upset because they feel they're being marginalised or treated differently; men get upset because they think we're being over-sensitive, especially when the cause is something unintentional.  I sometimes wonder, as I'm sure other people do, if perhaps picking up every incident harms our cause more than advancing it.  But then I feel that
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Location: London W8, UK
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Mike and I debut our new Disruptor presentation

Last Tuesday  Mike and I unveiled our brand shiny new presentation: Understanding the Disruptor, a Beginner's Guide to Hardcore Concurrency .  This was a preview of the talk we'll be doing at JAX London on the 2nd November. A video of the session is available, as are the slides .  I promise not to say "so" anywhere near as many times when I repeat my performance at JAX (is there anything more painful than watching yourself on video?). I thought the session went really really well.  We got some great questions at the end, we had an audience that was engaged, and I was dead pleased we didn't lose anyone with the assembly language.  We had some very valuable feedback afterwards too. As well as our presentation, there were three great lightning talks: Somay Nakhal on Java Thread States - Somay gave a nice overview of thread lifecycles with code and some great diagrams.  I liked how he made this more applicable to the real world than the sort of book exampl
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JavaOne 2011: Roundup

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Having been back in London for a few days I've had some time to digest the madness that was last week. My lasting impression of JavaOne is almost entirely positive.  Granted, it was my first major conference, so maybe I'm just not jaded yet.  But let me tell you what I loved about it (yes, I did cover some of these in my last post ): First and foremost, the people.  I don't remember meeting a single grumpy person. Everyone I spoke to was there to get the most out of the experience, regardless of how many times they'd been previously.  In my experience, techies are not conditioned to be socially comfortable, yet introductions were made and the conversations flowed easily. Of course it wasn't just the attendees who were friendly, the staff and organisers were approachable and helpful, and it was nice to have people hanging around to direct you. One of the (few) advantages of having the event over multiple hotels was the outdoor space between them.  It's un
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JavaOne: Initial Observations

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So I've been at JavaOne for the better part of three days, it's time to record some of my observations so far: The wireless access is rubbish. <Gross generalisation> technical people are not natural public speakers.  Makes me feel better about the presentations I'm going to be giving (see A Beginner's Guide to Hardcore Concurrency ). The sessions are less useful than getting out and chatting.  I've had a really excellent time, I've met: people from other Java User Groups; the Duchess girls; other Duke Award winners; the Azul guys; guys (well, girls) from O'Reilly books; JCP members and many random and awesome people. Everyone thinks that Large is an acceptable default t-shirt size (it's not).  Vendors - if you're really serious about appealing to The Other Gender you need to stock XS, if not actual skinny tees. If you're running a conference, you should probably have your projection screens above the height of the audience members
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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 heart of the patte
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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 the first bi
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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 needs a se
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