On 15/01/2026 11:52, Roman Kennke wrote:
:
thanks for offering your perspective. I have changed both POCs (and
the corresponding example code) to implement as JVMTI extensions - I
didn't even know that such a mechanism exists.
They currently still use a capability to set up what they need (and
that's in the public API unfortunately), I am wondering if there is
something similar for JVMTI extensions? Worst case, I would perhaps
add another extension function to initialize things.
Also, is there any way for consumers of the API to get some
documentation? The second POC uses callbacks, and I suppose it might
be useful for a prospective user of the API to know the arguments etc
of those. As it currently is, the callback functions are basically
black boxes, reported by the extension mechanism as void* - the user
of the API would have to know what functions exactly to pass as
callbacks. (Worst case, I guess it could be described in a blog-post
or so.)
I think it would be okay to have the equivalent of @implNote in the
JVMTI spec. As part of the JEP 451 implementation we added an
"Implementation Note" to the "Agent Start-Up (Live phase)" section to
document a -XX option. Maybe the "Stack frame" or some other section
could have an implNote to document the functions?
I don't think the extension mechanism anticipated new capabilities but
it could be done, as you mention, with another extension function.
(Serguei might have some ideas here but I suspect it could be
problematic to use some of the bits for VM-specific capabilities).
-Alan
