Walk stack in signal handler

[Roman Kovalenko]

Hi,

Thank you for the reference. I was already a little familiar with
PreserveFramePointer but after reading the related mailing list thread I
have better understanding and it will definitely help me in my future
researches. The main problem for me for now is that I have poor knowledge
of where to look for locals of frame that is already found by
AsyncGetCallTrace and its helpers, because I cannot access locals (or
access just 'this' which is enough) with calls that are used for same
purpose within safepoint (e. g. JVMTI GetLocalInstance etc.). I have tried
some random workarounds as well, but without deeper knowledge they had no
success yet. Maybe there was a discussion about the stack state outside
safepoint? :) Something like that would help me a lot, since I have
difficulties to get right direction for source code reading.

Thanks.

On Wed, Feb 17, 2016 at 7:40 PM, Volker Simonis <volker.simonis at gmail.com>
wrote:

> Hi Roman,
>
> you should definitely use -XX:+PreserveFramePointer and you should
> also have a look at the discussion on bug "8068945: Use RBP register
> as proper frame pointer in JIT compiled code on x86" which discuss
> some of the difficulties related to native stack walking in hotspot:
>
> https://bugs.openjdk.java.net/browse/JDK-8068945
>
> Regards,
> Volker
>
>
> On Wed, Feb 17, 2016 at 6:28 PM, Roman Kovalenko <rmnkvlnk at gmail.com>
> wrote:
> > Hi,
> >
> > Looks like that I am able to get 'this' for native frame with
> > frame::get_native_receiver() but I cannot do anything with any other
> frame
> > type.
> > How can I find out what is permitted to be used outside safepoint? Also,
> > what can happen to frame outside safepoint, because of what is it hard to
> > walk it? May be I should look in some precise source code locations?
> >
> > Thanks.
> >
> > On Fri, Feb 12, 2016 at 11:48 AM, Andrew Haley <aph at redhat.com> wrote:
> >
> >> On 11/02/16 17:54, Roman Kovalenko wrote:
> >>
> >> > I would like to profile application by interrupting it with signals
> and
> >> > using AsyncGetCallTrace then. This works well, but also I want to
> collect
> >> > every 'this' for any object method frame that is walkable by AGCT. I
> >> looked
> >> > around (forte.cpp and related) but had no success.
> >> >
> >> > Is it even possible?
> >>
> >> It's difficult.  The compilers move values around and things are
> >> really only stable at safepoints.
> >>
> >>
> >
> >
> > --
> > -rmnk-
>



-- 
-rmnk-