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Memory Access Patterns Are Important

In high-performance computing it is often said that the cost of a cache-miss is the largest performance penalty for an algorithm. For many years the increase in speed of our processors has greatly outstripped latency gains to main-memory. Bandwidth to main-memory has greatly increased via wider, and multi-channel, buses however the latency has not significantly reduced. To hide this latency ...

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Oracle Service Bus – Stuck Thread Case Study

java-interview-questions-answers

This case study describes the complete root cause analysis process of a stuck thread problem experienced with Oracle Service Bus 11g running on AIX 6.1 and IBM Java VM 1.6.  This article is also a great opportunity for you to improve your thread dump analysis skills and I highly recommend that you study and properly understand the following analysis approach. ...

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5 tips for proper Java Heap size

java-interview-questions-answers

Determination of proper Java Heap size for a production system is not a straightforward exercise. In my Java EE enterprise experience, I have seen multiple performance problem cases due to inadequate Java Heap capacity and tuning. This article will provide you with 5 tips that can help you determine optimal Java Heap size, as a starting point, for your current ...

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JRockit – JRCMD useful commands

I have been using JRockit since many years 2007. I find it slower than Hotspot, but it has been always better on diagnosis and analysis of problems. Since last summer, I have been working for an international telecommunication systems vendor. We design and implement various products for telecom operators, on top of HP OpenCall Convergent Communication Platform. I am fan ...

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Tracking excessive garbage collection in Hotspot JVM

Quite frequently due to memory leaks or other memory problems applications freeze leaving only the garbage collector (GC) process running unsuccessfully trying to free some space. This happens until watchdog (or frustrated administrator) restarts the application and the problem is never solved. The goal of this article is to show how to identify excessive GC and to get a heap ...

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Just in Time Compiler (JIT) in Hotspot

The Just In Time Compiler (JIT) concept and more generally adaptive optimization is well known concept in many languages besides Java (.Net, Lua, JRuby). In order to explain what is JIT Compiler I want to start with a definition of compiler concept. According to wikipedia compiler is ‘ a computer program that transforms the source language into another computer language ...

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How to analyze Thread Dump – IBM VM

This article is part 4 of our Thread Dump analysis series which will provide you with an overview of what is a JVM Thread Dump for the IBM VM and the different Threads and data points that you will find. As you will see and learn, the IBM VM Thread Dump format is different but provides even more out-of-the-box troubleshooting ...

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OutOfMemoryError: Java heap space – Analysis and resolution approach

 java.lang.OutOfMemoryError: Java heap problem is one of the most complex problems you can face when supporting or developing complex Java EE applications. This short article will provide you with a description of this JVM HotSpot OutOfMemoryError error message and how you should attack this problem until its resolution. For a quick help guide on how to determine which type of ...

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