Gregg Sporar's Blog

Memory Leak Geek

I was going to call this entry "I Have a Memory Leak Fetish," but that just sounded too weird.... :-)

I have never been able to completely explain my fascination with memory leaks. I assume it is related to my general interest in what I like to think of as "forensic software development." You know the drill: a big pile of code (which you may or may not have written) is broken and no one knows why. So your boss comes into your office and says, "The system is crashing. You have to fix this now." Whether you have ever seen the code before is not relevant.

I've been through this drama and on more than one occasion the fire drill was caused by a memory leak. Technically speaking a memory leak is just another type of bug, but somehow it feels different. As a general rule memory leaks are not usually logic errors - they're just inefficiencies. Sometimes you can hide them by increasing the size of the heap the JVM uses to run your application.

But if you are unable to hide a memory leak then you have to find it before you can fix it. In some situations this is easy to do and in others it is not. There are a variety of tools available to help. Some of those tools are free and others are not. Some of the tools let you observe the heap and others let you actually instrument your code in order to learn more about its behavior.

So which tool(s) do you use for finding memory leaks? I've formed some opinions on this topic and turned them into a BOF at JavaOne this year: Memory Leaks in Java™ Technology-Based Applications: Different Tools for Different Types of Leaks. It will be on Thursday night at 8:30, which is a tough time slot because the After Dark party will be going on. But from what I've heard, the After Dark party will be structured so that you can drop into it, hang out for a while, and then easily re-join later. So if you are a memory leak geek (or would like to become one), come to my BOF. I'll talk through a couple of examples from production applications in which I found memory leaks. And of course I'll demo some tools, including both the profiler from YourKit and the NetBeans Profiler.

There will also be some demos of the NetBeans Profiler on May 15 at NetBeans Day San Francisco. The first four hundred people through the door in San Francisco will get a free copy of the NetBeans IDE Field Guide, 2nd Edition and a free USB drive. Seats are limited, so register now. The event is free and you do not have to be registered for JavaOne in order to attend.

Comments

• Could we, who can not be on JavaOne, get your presentaion? I'm very interested in how to find bugs, memory leaks with NetBeans Profiler.

  Posted by: kovi on May 05, 2006 at 03:51 AM

• kovi: I'll be doing another blog entry right after JavaOne that recaps my presentation; it will contain all the links, etc. So stay tuned. Until then, there is a tutorial available for the NetBeans Profiler here.

  Posted by: gsporar on May 05, 2006 at 04:47 AM

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