Getting the Heap virtual addresses?

[Krystal Mok]

Hi Azeem,

(Sorry for the late reply. Just in case someone interested who's not
familiar with Serviceability Agent...)

The "universe" command in CLHSDB would fit your need perfectly.
For example,

$ java -cp $JAVA_HOME/lib/sa-jdi.jar sun.jvm.hotspot.CLHSDB
hsdb> attach 1234
Attaching to process 1234, please wait...
hsdb> universe
ParallelScavengeHeap [ PSYoungGen [ eden =
 [0x00000000fd560000,0x00000000fedc00a0,0x00000000ff4c0000] , from =
 [0x00000000ff750000,0x00000000ff9da020,0x00000000ff9e0000] , to =
 [0x00000000ff4c0000,0x00000000ff4c0000,0x00000000ff750000]  ] PSOldGen [
 [0x00000000f8000000,0x00000000f82eb078,0x00000000fa9b0000]  ] PSPermGen [
[0x00000000f2e00000,0x00000000f3970798,0x00000000f42c0000]  ]  ]
hsdb> quit
$

If you need to programmatically print this information, you could use
sun.jvm.hotspot.gc_interface.CollectedHeap.print().
For example,

import sun.jvm.hotspot.gc_interface.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.tools.*;

public class ShowUniverse extends Tool {
    public void run() {
        CollectedHeap heap = VM.getVM().getUniverse().heap();
        heap.print();
    }

    public static void main(String[] args) {
        ShowUniverse tool = new ShowUniverse();
        tool.start(args);
        tool.stop();
    }
}

And used as:

$ javac -classpath $JAVA_HOME/lib/sa-jdi.jar ShowUniverse.java
$ java -cp .:$JAVA_HOME/lib/sa-jdi.jar ShowUniverse 1234
Attaching to process ID 1234, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 22.0-b10
ParallelScavengeHeap [ PSYoungGen [ eden =
 [0x00000000fd560000,0x00000000fedc00a0,0x00000000ff4c0000] , from =
 [0x00000000ff750000,0x00000000ff9da020,0x00000000ff9e0000] , to =
 [0x00000000ff4c0000,0x00000000ff4c0000,0x00000000ff750000]  ] PSOldGen [
 [0x00000000f8000000,0x00000000f82eb078,0x00000000fa9b0000]  ] PSPermGen [
[0x00000000f2e00000,0x00000000f3970798,0x00000000f42c0000]  ]  ]

$

If you need to access the individual virtual addresses programmatically,
just look at the implementations of CollectedHeap.printOn(PrintStream tty)
in GenCollectedHeap/ParallelScavengeHeap/G1CollectedHeap for example.

Hope that helps,
Kris

On Mon, Oct 1, 2012 at 9:10 PM, Azeem Jiva <azeem.jiva at oracle.com> wrote:

>  Krystal,
>   That would work as well, I just need some way of getting the data while
> the JVM is running.
>
>
> On 09/30/2012 08:58 PM, Krystal Mok wrote:
>
> Hi Azeem,
>
>  It'd be easy to get with an SA agent instead of a JVMTI agent. Would
> that do for you?
>
>  - Kris
>
> On Sat, Sep 29, 2012 at 2:08 AM, Azeem Jiva <azeem.jiva at oracle.com> wrote:
>
>> Is there a way to get at the virtual addresses for the heap from a JVMTI
>> agent?  The data is clearly available as PrintGCDetails dumps the
>> information at the end of the run.
>>
>> --
>> Azeem Jiva
>> @javawithjiva
>>
>>
>
> --
> Azeem Jiva
> @javawithjiva
>
>
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