Performance Management of Java Applications

Today I would like discuss on Performance Management of Java applications and handling memory leaks in Java. Having spend some unnerving moments and time myself ,related to handling memory leaks (OutOfMemoryError) issues in one the enterprise application being already in production in a clustered environment recently,I was faced with having long meetings and discussions with the customer and the people in the higher hierarchy level at the company ,to fine tune their application which was the source of generating more revenue and profits to them and as a Senior Consultant , I was looked upon as source of providing guidance and technical tips to achieve that.And thats when I realized that not always the old paradigm that while using Java we need not worry about allocating and freeing memory of objects holds true...And here Iam not giving you an overview on the steps or the code I followed & wrote,better you learn yourself,but rather an overview on the tools you can use to manage and fine tune Java applications. To start with let us understand the term Garbage Collection in Java and in the process of submitting the proof of concept to the customer,the tools that can be used for handling such scenarios ,as part of my R&D I came across the tools mentioned below which will certainly help Java developers in fine tuning their applications and my personal favorite is YourKit Java Profiler.

Garbage Collection in Java
In Java ,you create objects, and JVM takes care of removing them when they are no longer needed by the application through a mechanism known as garbage collection.The job of the garbage collector is to find objects that are no longer needed by an application and to remove them when they can no longer be accessed or referenced. The garbage collector starts at the root nodes, classes that persist throughout the life of a Java application, and sweeps though all of the nodes that are referenced. As it traverses the nodes, it keeps track of which objects are actively being referenced. Any classes that are no longer being referenced are then eligible to be garbage collected. The memory resources used by these objects can be returned to the Java virtual machine (JVM) when the objects are deleted...And how best can you do that? Below is the brief synopsis of the tools you can use in Java for performance tuning.

Tools you can use for handling memory leaks and performance management

VisualGC- Visual Garbage Collection Monitoring tool
The visualgc tool attaches to an instrumented HotSpot JVM and collects and graphically displays garbage collection, class loader, and HotSpot compiler performance data.

JSTAT

The jstat tool displays performance statistics for an instrumented HotSpot Java virtual machine (JVM). The target JVM is identified by its virtual machine identifier, or vmid option described below.

Note:This utility is unsupported and may not be available in future versions of the J2SE SDK. It is not currently available on Windows 98 and Windows ME platforms.

JMap
jmap prints shared object memory maps or heap memory details of a given process or core file or a remote debug server.This utility is unsupported and may or may not be available in future versions of the J2SE SDK.

Hat

HAT is a program that analyzes a heap dump file for Java programs. This tool can help a developer to debug and analyze the objects in a running Java program. It is particularly useful when debugging unintentional object retention. Starting with Java SE 6, HAT has been replaced with jhat, which is included with the standard Sun distribution. HAT is not being maintained in a stand-alone configuration. The Heap Analysis Tool (HAT) helps to debug unnecessary object retention (sometimes called "memory leaks") by providing a convenient means to browse the object topology in a heap snapshot, which is generated by the Java VM. HAT reads a hprof file, then sets itself up as a web server--therefore allowing you to run queries against a heap dump contained within the hprof file.For further information, read this article

JProbe

JProbe is an enterprise-class Java profiler providing intelligent diagnostics on memory usage, performance and test coverage, allowing developers to quickly pinpoint and repair the root cause of application code performance and stability problems that obstruct component and integration integrity. With JProbe’s intuitive, unified UI, it’s easier to navigate and configure all JProbe analysis tools.JProbe also provides a powerful filtering mechanism for controlling the data display, including nine different metrics for sorting and coloring data for clutter-free, easier viewing.

Yourkit Java Profiler

The best part about Yourkit Java Profiler is , it does integrate seamlessly with different IDEs like Eclipse,Intellij etc and provides full support for Java 5 and Java 6.For the list of benefits and features,this great tool provides ,read this.

And thats all for now,say whatever you want to and any other tools that can be used for handling memory leaks in Java.

Rational Purify
IBM Rational Purify is a runtime analysis solution designed to help developers write more reliable code. Reliability is ensured via two crucial functions: memory corruption detection and memory leak detection.For further understanding about using Rational Purify , read this article

Suggested Video Tutorial

Maintaining Java Apps in Production Environment- by Alexandre Rafalovitch at InfoQ

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