Xebia Blog

As promised last week, I am continuing the countdown of Enterprise Java performance problems. Today it's number 9.

An incorrect application server configuration can have such a detrimental effect on the performance of your application, that it pays to learn about the options your application server and its JVM offer to tune their performance.

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Filed under: Java, Performance
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Our Agile software development process is a complete package. Many clients we present our ideas and solutions to, feel overwhelmed by the new mechanisms and interactions that it proposes. They are a bit taken back by the changes they face when they would introduce this new approach. Somehow they imagine all these changes have to take place at once in a big bang implementation of the new development process. This is quite contradictory to what the principles of Agile promise: The process is adaptable, to changes, but also to existing situations. Therefore I propose a new approach: GRADAP, Gradual Adaptation to the Agile Process.
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Filed under: Agile
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At J-Fall in October 2006 I gave a presentation on the top 10 performance problems encountered by me and my colleagues at Xebia. The list was created by brainstorming with a group of people and was based on the experiences we all had with performance in our own projects and projects where we were called in to remove performance bottlenecks.

Of course that is a very unscientific way to make such a list.

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Filed under: Java, Performance
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One day, one of our testers comes up to our table and tells us: "The testing environment (Weblogic container on IBM JDK 1.4.2) is hanging"... So we kill Weblogic, fire it up again and have the tester replay his scenario. He manages to reproduce the hanging behaviour. So on come the Java Forces to find the problem. As the JDK is an 1.4.2 JDK we cannot use the Java5 jconsole to inspect the JVM. The easiest then is to first create a stack dump, as we want to see what the threads are doing. Upon careful inspection of the dump file we first find this disturbing snippet.
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Filed under: Java
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The origins of lean thinking lie in production and there’s quite a bit of interest in finding parallels between current software development practices and those of manufacturing. The Poppendiecks for instance, frequently quote examples from classic manufacturing companies (Ford, GM, Dell, Toyota) to help understand why agile methods are a very effective approach to software development. Oddly enough they (and many, many others) are hesitant to buy fully into the concept that manufacturing industries and software development have indeed much in common.

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Filed under: Articles, General
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At my current project we have to parse a large CSV-file with related data. Each line contains an "entity" or "object" and most lines are related through some references to other lines. The data needs to be send to the server, but some validations and manipulations have to be performed beforehand. Files could become so large, that holding all objects in memory at the client machine could be a problem. We decided to use a Database to temporarily hold the data and to search for related lines. The lines are not necessarily ordered, so we need to wait for the last line to be parsed before validating and manipulating the data. We would like the data to be captured in a nice object oriented model. We used Hibernate and Apache Derby for our implementation and it turned out to be quite convenient!
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Filed under: Hibernate
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One of the most important assets at Xebia is the knowledge of its consultants. Therefore we need to pay special attention to harvesting, exchange and expanding that knowledge. One of the ways we do that at Xebia is by holding bi-weekly sessions we like to call XKE's, short for Xebia Knowledge Exchange.

When we started doing these sessions three years ago, they were quite straight forward. The eight of us got together, had a pizza, and told each other about the projects we were doing. Since then Xebia has grown to 60 consultants, in the Netherlands alone, spread over two business units (Xebia IT Architects and Xebia Software Development). This put a strain on the old simple system. Even though the business units held separate sessions, the groups were simply getting too large!

Therefore we have gone about it in a different way since the summer of 2006. Every other XKE, once a month, we hold what you could call an internal conference. On a Tuesday from 16:00 till 21:00 three separate tracks with four sessions each are scheduled. The content of the sessions is mostly provided by the Xebia consultants themselves although external speakers are also invited sometimes. Not only presentations can be given here; there are also smaller rooms for interactive sessions such as brainstorms or hands-on sessions.

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Filed under: General
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