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Showing posts with the label process

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 Handover

New Blog Post: The Handover
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Adjusting to Working Remotely

One of the most obvious differences I faced when I moved from LMAX to 10gen were the working conditions. I don't mean like being deep underground in some dangerous situation vs being pampered by beautiful slave boys and girls. What I mean is that the working practices at one company necessitated being in the office for core hours, and at the other flexible hours and remote-working are practically mandatory. At at LMAX we pair-programmed most days, and that meant that being co-located: being in the same office, at the same computer, was pretty important. We could work from home when needed, but pairing is pretty tricky when you’re in a different room. The drivers' team at 10gen, on the other hand, is a very distributed team. Sure, I'm based in London, and we have an office here. But my main Java "pair" is in Boston, working from his home office. The other driver developers are distributed around the New York, Palo Alto and London offices, with m...
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Tales from the Other Side: Confessions of an Offshore Resource

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After the acquisition of a company with offices in New York, I pestered my company outrageously until they got fed up and finally relented – they agreed to send me to the US. To ease the transition, I chose to move onto a project which would allow me to start working in London and continue on the same team after I had moved to New York. In the extreme over-excitement that followed my relocation, it took me a little while to realise that effectively I was an offshore resource, no different really from any of our Indian test team, and the team needed to manage this appropriately. I learnt a number of lessons whilst playing this game. Some of these points are also valid for teams with remote resources (e.g. people working from home). The Time Zone Difference is the First Problem to Overcome Yes, the geographical separation and remote access is important to consider, but it's the time difference which is the killer. When your working day only (officially) overlaps for 4 hours, you ha...
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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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