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Showing posts from 2009

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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Comments on representations of our industry

I have not (yet) seen the presentation this post is referring to.  But I think many of the comments Ted makes are very valid, and our industry as a whole should occasionally stop and think.  I've seen Ted speak at QCon, and I've had a lot of time for his comments ever since. I'm aware that this blog is rapidly filling with comments about gender and perceptions and people-y stuff, when I originally wanted it to be a purely technical blog.  But I guess this other stuff interests me more.  And there are less people talking about it than there are talking about pure technical solutions to problems.
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Why changing jobs frequently is not necessarily a bad thing...

...in fact, it's actually a good thing .
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Sexism in IT?

Let's celebrate our IT women "Everyone" knows that there are more men than women in IT.  That it's a "boys" job.  Not a lot of people know that the first programmer was a woman.  Not a lot of people realise the number of women in IT is DECREASING.  And has been since the 80s.  In a working world where I honestly believe that *in general* there are more opportunities for women (OK, inline with the other stuff I've been reading I'll caveat this with white, middle-class women), it seems shocking that such a growth industry as IT is actually losing women, and appears unable to determine why, or stop the flow. I get asked a lot, as a girl programmer, why there aren't more women in IT.  This is a complicated issue and one I've been thinking about for years and still don't have any good answers, but I personally think it's more about perception than anything else. I don't think it's because you get more outright sexism and l...
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Scrum but...

Having experience Flaccid Scrum , I find this article interesting, and agree with most of it. I'd also like to add though, that if you do the scrum practices (story cards, stand ups, retrospectives, etc) but don't buy into the fundamental principals, you will not succeed.  And that means everyone on the team, not just the people in charge.  In particular, if the team is not empowered, is not committing to the estimates and the iteration plan in its heart, and and does not trust, then you are probably better off using traditional processes.  Or just as likely to fail whatever process you use.
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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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