This "How-To" guide gives you simple recipes for using Jinsight for the most common analysis tasks.  You do not have to read every section of this guide for it to be useful.  Begin with one of these major topics and proceed to find the task you need help with:

Where is my program spending its time?  Techniques to help you understand your program's time performance.

Understanding memory usage and data structures  Techniques to help you analyze memory problems, find the causes of memory leaks, and understand how your objects are created and interrelated.
 

Where is my program spending its time?

In this section we give you techniques for analyzing your program's performance.
 

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Before you go any further, read this section on tracing:

Tracing for performance analysis  This section shows you how to trace your program to analyze time performance problems.  It shows you how to choose a tracing technique based on information you already have about why your program is running slowly.  It also gives you techniques for handling large traces.

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Once you have created a trace, use the Jinsight visualizer to explore your program's behavior.  Below we give you various ways to use Jinsight for different stages of the performance analysis process.  Of course, as you make discoveries and come up with new questions, you will most likely iterate among these techniques.  You may then want to come back and take additional traces.
 
Explore your program and verify assumptions  This is a good place to start if you already have an understanding of how your program should run. This section shows you how to take a quick look at your program's behavior to verify that your assumptions are correct.  Often a performance problem occurs because your program is doing something you didn't expect.

Find hot spots  This is a good place to start if you are not sure where your program is spending its time. This section shows you how to zero in on the methods and classes causing the most activity.  It will also help you see these in the context in which they occur: you can see the phases of your program when time-consuming sequences occur.  This section also shows you how to quickly get an overview of memory activity from a time perspective, to see if your program is spending a lot of time creating and destroying objects.

Analyze calling patterns and repetitive sequences  You have identified a few methods which are generating much of the time-consuming activity.  Now you want to understand the calling patterns in more detail so you can diagnose the cause of the performance problem.  You may want to know what is causing a method invocation to take so much time, or you may want to see the bigger picture to understand why a method is being invoked so often.  This section also shows you how to work with repetitive calling sequences.

Analyze object creation and garbage collection  Your program is creating more objects than you had expected and you suspect that time is wasted unnecessarily creating or garbage collecting these objects.  This section shows you how to find and understand these cases.

Understanding memory usage and data structures

In this section are techniques to help you understand your program's objects, their use of memory, and the references among objects. Since each task requires different information to be collected in the trace, we describe the tracing options specific to a task in each of the recipes below.

Get an overview of memory usage  This section shows you how to see which classes are accounting for the most memory.  It can help you spot potential memory leaks, and also see if your program uses an excessive number of objects.

Explore data structures  This section shows you how to browse over the objects of your program to see the patterns in the references among objects.

Find the cause of a memory leak  A memory leak in Java is caused when an object that is no longer needed cannot be reclaimed because another object is still referring to it.  This section will help you verify that you have a memory leak, and help you understand your objects' references to find the cause of the leak.