In process debugger for Smalltak, JVMTI?

[Charles Oliver Nutter]

On Tue, May 17, 2011 at 12:08 PM, Mark Roos <mroos at roos.com> wrote:
> It looks like JVMTI supports this but I have not been able to find a Java
> class which gives access to the
> apis that look interesting.
>
> Is this the right way to go?
>
> Does anyone know of some existing work that I could leverage?

There's a couple directions possible...

Thobias Ivarsson, of the Jython project, hacked for a short amount of
time on a native library that binds the JVMTI functions for frame
inspection/mutation to JNI entry points, so they could be called from
Java. I'm not sure where that code lives now.

I have also used JDI to do frame inspection from within the same JVM.
It works reasonably well, but as you might expect it's not the fastest
thing in the world. Here's a sample, where I implemented ObjectSpace
(heap-walking looking for specific object types) entirely in Java
using JDI:

https://github.com/headius/jdi_objectspace

Because JDI only gets mirror references to objects int the remote JVM,
I was actually *forced* to use the frame modification capabilities. I
can confirm that it works.

I have also had an interest for some time in using one of the various
FFI layers (JNA, JFFI) to bind the JVMTI/JNI functions directly,
allowing you to call them consistently from Java code. So far I have
not made any progress on that.

- Charlie