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Tag Archives: JVM

Compact Off-Heap Structures/Tuples In Java

In my last post I detailed the implications of the access patterns your code takes to main memory. Since then I’ve had a lot of questions about what can be done in Java to enable more predictable memory layout. There are patterns that can be applied using array backed structures which I will discuss in another post. This post will ...

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JavaOne 2012: Diagnosing Your Application on the JVM

It was worth attending Staffan Larsen‘s (Oracle Java Serviceability Architect) presentation ‘Diagnosing Your Application on the JVM‘ (Hilton Plaza A/B) just for learning of the new jcmd command-line tool provided with Oracle’s JVM 7. The rest of the presentation was ‘bonus’ for me, which was nice for the last session I attended on Wednesday of JavaOne 2012. The Oracle HotSpot ...

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JavaOne 2012: Looking into the JVM Crystal Ball

I returned to Plaza A/B in the Hilton to attend the fourth session on Monday, but first went up to the top floor of the Hilton to pick up lunch. I’m reminded every year on the first day of JavaOne how surprisingly frustrating the first day’s lunch acquiring process is for everyone involved. I know I found the experience a ...

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VisualVM: Monitoring Remote JVM Over SSH (JMX Or Not)

java-interview-questions-answers

VisualVM is a great tool for monitoring JVM (5.0+) regarding memory usage, threads, GC, MBeans etc. Let’s see how to use it over SSH to monitor (or even profile, using its sampler) a remote JVM either with JMX or without it. This post is based on Sun JVM 1.6 running on Ubuntu 10 and VisualVM 1.3.3. 1. Communication: JStatD vs. ...

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Java Memory Profiling Simplified

As a typical Java developer I never monitored the memory usage of my application apart from following typical best practices like closing the connections, streams etc.. Recently we were struck with few issues in our JBoss servers that I had to dig in to the memory management.One of the best thing in java is that the developers are not required ...

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BTrace: hidden gem in Java developer toolbox

This post is about BTrace which I am considering as a hidden gem for Java developer. BTrace is a safe, dynamic tracing tool for the Java platform. BTrace can be used to dynamically trace a running Java program (similar to DTrace for OpenSolaris applications and OS). Shortly, the tool allows to inject tracing points without restarting or reconfiguring your Java ...

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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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