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

Michael Kopp

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Top Stories by Michael Kopp

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-world event. While that is true, the reverse is not. It is often forgotten that every single GC, even a minor one, is a stop-the-world event. Young Generation collections are only fast if there is a high mortality rate among young objects. That’s because they copy the few surviving objects an... (more)

Troubleshooting Response Time Problems

Production Monitoring is about ensuring the stability and health of our system, that also includes the application. A lot of times we encounter production systems that concentrate on System Monitoring, under the assumption that a stable system leads to stable and healthy applications. So let’s see what System Monitoring can tell us about our Application. Let’s take a very simple two-tier Web Application: A simple two tier web application This is a simple multi-tier eCommerce solution. Users are concerned about bad performance when they do a search. Let's see what we can find out a... (more)

How Garbage Collection Differs in the Three Big JVMs

(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... (more)

The Impact of Garbage Collection on Java Performance

In my last article I explained what a major Garbage Collection is. While a major Collection certainly has a negative impact on performance it is not the only thing that we need to watch out for. And in case of the CMS we might not always be able to distinguish between major and minor GC. So before we start tuning the garbage collector we first need to know what we want to tune for. From a high level there are two main tuning goals. Execution Time vs. Throughput The first thing we need to clarify if we want to minimize the time the application needs to respond to a request or if we... (more)

Why Perfomance Management Is Easier in Public than On-Premise Clouds

Performance is one of the major concerns in the cloud. But the question should not really be whether or not the cloud performs, but whether the Application in question can and does perform in the cloud. The main problem here is that application performance is either not managed at all or managed incorrectly and therefore this question often remains unanswered. Now granted, performance management in cloud environments is harder than in physical ones, but it can be argued that it is easier in public clouds than in on-premise clouds or even a large virtualized environment. How do I ... (more)