JVM tuning
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HeapAudit – JVM Memory Profiler for the Real World | Foursquare Engineering Blog
Feb 02nd HeapAudit is not a monitoring tool, but rather an engineering tool that collects actionable data – information sufficient for directly making code change improvements. It is created for the real world, applicable to live running production servers. HeapAudit is a foursquare open source project designed for understanding JVM heap allocations. It is implemented as a Java agent built on top of ASM .
Java 7: How to write really fast Java code | Javalobby
We Recommend These Resources When I first wrote this blog my intention was to introduce you to a class ThreadLocalRandom which is new in Java 7 to generate random numbers. I have analyzed the performance of ThreadLocalRandom in a series of micro-benchmarks to find out how it performs in a single threaded environment. The results were relatively surprising: although the code is very similar, ThreadLocalRandom is twice as fast as Math.random()! The results drew my interest and I decided to investigate this a little further. I have documented my anlysis process.Excellent! That has always been a sore point. Why don't you post your patch to jdk-collaboration.dev.java.net so at least all JDK contributors can take advantage of it today? Thanks Matthias Posted by Matthias on October 20, 2006 at 04:30 AM PDT #
How to fix the dreaded "java.lang.OutOfMemoryError: PermGen space" exception (classloader leaks) (Frank Kieviet)
... I've seen a few posts in the Java and JMX forums from developers who were wondering how to find out why JConsole wouldn't connect to their application. So I have decided to write this short blog entry in order to outline a few diagnosing tips... Note: if you are using JConsole - you might also want to try the Java VisualVM . Java VisualVM comes with the JDK since JDK 6 update 7. It can be used to troubleshoot, monitor, and improve applications performance.
Troubleshooting connection problems in JConsole (JMX, SNMP, Java, etc...)
Endre's Tech Corner!: Linux Java Thread Priorities workaround
For some annoying reason, Sun has decided that to run with threads with working thread priorities on Linux, you have to be root. The logic behind this decision, is that to heighten thread priorities, you have to be root. But, says many of us, could you not just let us lower thread priorities, at least? No, says Sun.
Memory is stored within the cache system in units know as cache lines. Cache lines are a power of 2 of contiguous bytes which are typically 32-256 in size. The most common cache line size is 64 bytes. False sharing is a term which applies when threads unwittingly impact the performance of each other while modifying independent variables sharing the same cache line.
False Sharing
We Recommend These Resources If you want to efficiently store large collections of data in memory. This library can dramatically reduce Full GC times and reduce memory consumption as well. The HugeArrayBuilder builds generated classes for the InterfaceType on demand. The builder can be configured to change how the HugeArrayList is created.
Collections Library for millions of elements | Javalobby
Most (if not all) productive systems doing anything important will use more than 1 java thread. And when something goes crazy and your cpu usage is on 100%, it is hard to identify which thread(s) is/are causing this. Or so I thought. Until someone smarter than me showed me how it can be done. And here I will show you how to do it and you too can amaze your family and friends with your geek skillz.
Identifying which Java Thread is consuming most CPU | Nomad Labs Code
Maximiliano Firtman discusses HTML5, the features it introduces, how it can be used for cross-platform mobile development, compatibility issues, creating apps for a store, taking a look at the future. Robert Godfrey discusses the requirements set at AMQP’s foundation: Applicability, Reliability, Fidelity, Interoperability, Manageability, Ubiquity, explaining how AMQP was designed for the future. Michael Nygard outlines 8 rules for dealing with complex systems: Embrace Plurality, Contextualize Downstream, Beware Grandiosity, Decentralize, Isolate Failure Domains, Data Outlives Applications ... Sedef Gavaz discusses the importance of adapting UX techniques used to the target audience, organization and culture, sharing lessons learned while working in China. In projects that are implementing Scrum, the role of the Scrum Master is very crucial. This article focuses on what is Servant Leadership and the principal characteristics of a Servant Leader.
Java without the GC Pauses: Keeping Up with Moore’s Law and Living in a Virtualized World
We Recommend These Resources I found this article series very interesting All about 64-bit programming in one place which collects "a lot of links on the topic of 64-bit C/C++ software development." However some of these issues are relevant to Java and can make a difference.
Java: All about 64-bit programming | Javalobby
Trove
Provide "free" (as in "free speech" and "free beer"), fast, lightweight implementations of the java.util Collections API. These implementations are designed to be pluggable replacements for their JDK equivalents. Provide primitive collections with similar APIs to the above. This gap in the JDK is often addressed by using the "wrapper" classes (java.lang.Integer, java.lang.Float, etc.) with Object-based collections. For most applications, however, collections which store primitives directly will require less space and yield significant performance gains. Trove allows both server-side and client applications to work faster and use less memory.How to tame java GC pauses? Surviving 16GiB heap and greater. | Javalobby
We Recommend These Resources Memory is cheap and abundant on modern servers. Unfortunately there is a serious obstacle for using these memory resources to their full in Java programs. Garbage collector pauses are a serious treat for a JVM with a large heap size.Visualising Garbage Collection in the JVM | RedStack
Recently, I have been working with a number of customers on JVM tuning exercises. It seems that there is not widespread knowledge amongst developers and administrators about how garbage collection works, and how the JVM uses memory. So, I decided to write a very basic introduction and an example that will let you see it happening in real time!We Recommend These Resources Joshua Bloch had a great talk called Performance Anxiety (30min, via Parleys; slides also available ) at Devoxx 2010, the main message as I read it was Nowadays, performance is completely non-predictable. You have to measure it and employ proper statistics to get some meaningful results.
Joshua Bloch: Performance Anxiety – on Performance Unpredictability, Its Measurement and Benchmarking | Javalobby
This document provides information on typical command-line options and environment variables that can affect the performance characteristics of the Java HotSpot Virtual Machine. Unless otherwise noted, all information in this document pertains to both the Java HotSpot Client VM and the Java HotSpot Server VM. Categories of Java HotSpot VM Options Standard options recognized by the Java HotSpot VM are described on the Java Application Launcher reference pages for Windows , Solaris and Linux .