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Which Java thread consumes my CPU?

What do you do when your Java application consumes 100% of the CPU? Turns out you can easily find the problematic thread(s) using built-in UNIX and JDK tools. No profilers or agents required. For the purpose of testing we’ll use this simple program: public class Main { public static void main(String[] args) { new Thread(new Idle(), 'Idle').start(); new Thread(new Busy(), ...

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Java Thread at RUNNABLE state is not really running

Recently, I was doing an analysis/tuning on a Java application server installation in order to identify the bottlenecks and fix them. The most common action in such procedure (tuning) is to retrieve many Thread dumps, when system is on load. Please have in mind that heavy load (for some cases) may have side effects that they may lead us to ...

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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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