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In the Cloud, you have to trust your instruments...

Michael Kopp

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Top Stories by Michael Kopp

(Note: If you’re interested in WebSphere in a production environment, check out Michael's upcoming webinar with The Bon-Ton Stores) Most articles about Garbage Collection ignore the fact that the Sun Hotspot JVM is not the only game in town. In fact whenever you have to work with either IBM WebSphere or Oracle WebLogic you will run on a different runtime. While the concept of Garbage Collection is the same, the implementation is not and neither are the default settings or how to tune it. This often leads to unexpected problems when running the first load tests or in the worst case when going live. So let’s look at the different JVMs, what makes them unique and how to ensure that Garbage Collection is running smooth. The Garbage Collection ergonomics of the Sun Hotspot JVM Everybody believes to know how Garbage Collection works in the Sun Hotspot JVM, but lets take a c... (more)

Why Averages Are Inadequate, and Percentiles Are Great

Anyone who ever monitored or analyzed an application uses or has used averages. They are simple to understand and calculate. We tend to ignore just how wrong the picture is that averages paint of the world. To emphasis the point let me give you a real-world example outside of the performance space that I read recently in a newspaper. The article was explaining that the average salary in a certain region in Europe was 1900 Euro's (to be clear this would be quite good in that region!). However when looking closer they found out that the majority, namely 9 out of 10 people, only ea... (more)

So What? – Monitoring Hadoop Beyond Ganglia

Over the last couple of months I have been talking to more and more customers who are either bringing their Hadoop clusters into production or have already done so and are now getting serious about operations. This leads to some interesting discussions about how to monitor Hadoop properly and one thing pops up quite often: Do they need anything beyond Ganglia? If yes, what should they do beyond it? The Basics As in every other system, monitoring in a Hadoop environment starts with the basics: System Metrics - CPU, Disk, Memory you know the drill. Of special importance in a Hadoo... (more)

Major Garbage Collections - Separating Myth from Reality

In a recent article we have shown how the Java Garbage Collection MXBean Counters have changed for the Concurrent Mark-and-Sweep Collector. It now reports all GC runs instead of just major collections. That prompted me to think about what a major GC actually is or what it should be. It is actually quite hard to find any definition of major and minor GCs. This well-known Java Memory Management Whitepaper only mentions  in passing that a full collection is sometimes referred to as major collection. Stop-the-world One of the more popular definitions is that a major GC is a stop-the-w... (more)

Application Performance Monitoring in Production

Last time I explained logical and organizational prerequisites to a successful production level application performance monitoring. I originally wanted to look at the concrete metrics we need on every tier, but was asked how you can correlate data in a distributed environment, so this will be the first thing that we look into. So let’s take a look at the technical prerequisites of successful production monitoring. Collecting data from distributed environment The first problem that we have is the distributed nature of most applications. In order to isolate response time problems or... (more)