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Showing posts from April, 2008

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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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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Metrics and Incentives.

This  is a great example of what happens when you try to incentivise intelligent people on very simple metrics. They cheat. This was well described in Freakonomics , and something Mr On Software bangs on about regularly .  It's clear that there isn't really a good answer to the problem - actually that's not true.  The answer to the problem is to have everyone working in a job they are happy in and proud of, one where they are intrinsically motivated, and give them enough information to allow them to make the correct calls when it comes to prioritising work.  But I'm guessing that a large portion of the working world does not fall into this category.
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Certification

I know there are arguments against certification, and I definitely think that using certifiction to determine whether to interview or recruit people is downright daft, because frankly learning a bunch of answers isn't all that difficult.  But I personally find that completing a certification really helps to round out my knowledge in an area.  I guess my thoughts are that a fairly recent certification combined with the work experience to back it up is something that would make your CV more interesting to recruiters. As someone who has worked more on web apps than "core" Java applications, I found the 1.5 SCJP dead useful for drumming into me the facts about threading etc that I don't usually think too much about.  Plus since I did it very shortly after 1.5 started being used in anger, it was a good way to get familiar with the new features.  Although honestly it could've banged on a bit less about Generics, the stuff that was in th...
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AOP Caching

Today I would like to document my experiences implementing caching with Aspect Oriented Programming (AOP) and annotations.  Background context   Caching may need to be implemented in your application for a number of reasons. OK, actually usually only one: performance. I would like to add my own tuppence-worth to this though - if you can get away without caching (specifically in application that provide the ability to view and change data) then do so, unless you are using a cache implementation that will handle as much of the pain as possible for you. Implementing a home-grown cache from scratch is almost never the correct thing to do in my experience, you spend lots of time debugging and tweaking the cache when you should be working on your day-job, not re-inventing something that someone, somewhere, has already done a perfectly good job of .  The example I'm about to show you is for a web application created to let users read and edit values from a database (not an unusu...
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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: 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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