Home » Tag Archives: JVM (page 4)

Tag Archives: JVM

Daemonizing JVM-based applications

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Deployment architecture design is a vital part of any custom-built server-side application development project. Due to it’s significance, deployment architecture design should commence early and proceed in tandem with other development activities. The complexity of deployment architecture design depends on many aspects, including scalability and availability targets of the provided service, rollout processes as well as technical properties of the ...

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A little bit on the JVM and JIT

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As you might be aware, the JVM (Java Virtusal Machine) is what makes it possible for Java to adhere to the write-once-run-anywhere paradigm. At its core, the JVM consists of the following components: Heap Stack PermGen and Method Area JIT Compiler Code cache     The heap is where memory is allocated for every new operator you use during the ...

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MineCraft and off heap memory

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Overview MineCraft is a really good example of when off heap memory can really help. The key requirements are: The bulk of the retained data is a simple data structure (in minecraft’s case its lots of byte[]) The usage of off heap memory can be hidden in abstraction.     The test I used the following test for starting minecraft ...

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OutOfMemoryError on overprovisioned heap

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Why am I getting the OutOfMemoryError when allocating a data structure that should happily fit within the heap I have provided for the JVM? This was a question I recently faced. Indeed, when looking at what the developer was trying to accomplish and triple-checking the heap size given to the JVM via the -Xmx parameter, it indeed seemed that something ...

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ClassNotFoundException: is it slowing down your JVM?

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Most Java developers are familiar with the infamous and very common java.lang.ClassNotFoundException. While the sources of this problem are generally well understood (missing classes/libraries in classpath, class loader delegation problems etc.), the impact to the overall JVM and performance is often unknown. This situation can lead to significant impacts to your application response time and scalability. Large Java EE enterprise ...

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Difference between WeakReference vs SoftReference vs PhantomReference vs Strong reference in Java

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WeakReference and SoftReference were added into Java API from long time but not every Java programmer is familiar with it. Which means there is a gap between where and how to use WeakReference and SoftReference in Java. Reference classes are particularly important in context of How Garbage collection works. As we all know that Garbage Collector reclaims memory from objects ...

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Migrating from javaagent to JVMTI: our experience

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When you need to gather data from within the JVM, you will find yourself working dangerously close to the Java Virtual Machine internals. Luckily, there are ways you can avoid getting bogged down by JVM implementation details. The fathers of Java have given you not one but two beautiful tools to work with. In this post we will explain the ...

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An open source JVM Sampling Profiler

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It’s a well known deficiency of most existing sampling Java profilers that their collection of stack traces has to happen at a safe point. This is the case for profilers such as the sampling profiler, which uses the SUN/Oracle management agent to gather its stack traces. The problem with this approach is that it introduces both a sample bias since ...

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Allocating memory for the JVM: a case study

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This post is about a recent performance tuning exercise. As always, these start with vague statements about symptoms. This time the devil took the form of “The application is slow and we do not have the access to source code. What are our options to improve the situation”. A closer look to the application revealed it consisting of several batch ...

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