Debugging the Java Heap

[tmiranda]

One of my plugins is eating all of the Java Heap and I'm having difficulty tracking down the bug. Is there a way to see what Objects are in the Java Heap?

[stuckless]

What you are looking for is a Java Profiler. I've never run one with sagetv before, but you may be able to start here...

http://java.sun.com/developer/techni...ing/HPROF.html

And then see, if perhaps, your IDE has any profiling tools. I used to use JRat a long time ago as well... but I haven't actually used any recent ones (I think eclipse that TPTP?? Testing and Performance something). Netbeans has something as well.

Typically, if you are running out heap space... you might have an endless loop condition. I use the FindBugs plugin a lot to help me "clean" up my code. It finds all sorts of little programming gotchas... it's pretty easy to use, and you can run it from eclipse, against a project (which is what I do)... you might want to run it first, to see what it finds. i recommend running it anyways.

[broconne]

I second Stuckless's recommendation of using FindBugs - it is a great static analysis tool.

I can recommend JProbe as well, JDB is a great start - but since you are not invoking the JVM - I am not sure how you are going to attach any tool to the running VM. There are tools for analyzing heapdumps - If you are on windows, I am not sure how you can force sage to create a heapdump either. On linux, you might be able to send a kill command and create a heapdump - depending on the JVM.

You can attach with JConsole - but I don't think that will give you any details about memory usage.

Do you have any idea what might be causing it? Could share that part of the code and I am sure others could look for some unintended object retention.

[tmiranda]

Sean, broconne,

Thanks for the suggestions. I'm using Netbeans as an IDE so I'll see what tools I can find there.

I have no idea what code is causing the out of memory error, but I think it's an endless loop somewhere because there is a slight delay before things blow up.

It might also be caused by my caching of data in memory. I remove all references to the data when I'm done so the GC can reclaim the memory but maybe it's taking a long time to cleanup?

Tom

[jphipps]

Originally Posted by tmiranda

Sean, broconne,

Thanks for the suggestions. I'm using Netbeans as an IDE so I'll see what tools I can find there.

I have no idea what code is causing the out of memory error, but I think it's an endless loop somewhere because there is a slight delay before things blow up.

It might also be caused by my caching of data in memory. I remove all references to the data when I'm done so the GC can reclaim the memory but maybe it's taking a long time to cleanup?

Tom

You can use jvisualvm, which is part of the normal 1.6 java distribution. You just have to run the sage server as a foreground process and not as a service. Once you start sage and then start jvisualvm, you will see sage running and can connect to it using JMX and you can see the live object/memory utilization and do thread/memory dumps to see where memory is being used...

Thanks,
Jeff