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From "Aleksey Ignatenko" <aleksey.ignate...@gmail.com>
Subject Re: [classlib][launcher] Signal handler disabling
Date Mon, 12 Feb 2007 08:25:07 GMT
I experimented with minidumps on drlvm exception handler some time ago and
could make it working. The problem is that minidump functionality (dbghelp
library) as it described in documentation is fully supported by structured
exception handler, but I had problems with vectored exception handler (which
is in drlvm) ptinting stack of main thread (where exception happent). As you
know there is structured exception handler in launcher, therefore I succeded
to realize minidumps support there.

My opinion, is that default mode should have exception handler in classlib
turned on with dump files support. Default mode is a mode of users, in case
of crash anyone should be able to send dump file to developers for analysis.
And developers should use special flags to handle crashes with debugger.


On 2/12/07, Mark Hindess <mark.hindess@googlemail.com> wrote:
>
>
> On 12 February 2007 at 10:27, "Aleksey Ignatenko" <
> aleksey.ignatenko@gmail.com> wrote:
> >
> > Gregory, please look at
> > *HARMONY-3124*<https://issues.apache.org/jira/browse/HARMONY-3124
> >(Generation
> > of minidumps files on crash). This is about generating minidump
> > files on the basis of crash handler in launcher. Minidump is similar to
> dump
> > file on linux. There is much more possibilities to analize the problem
> with
> > it.
>
> This could be handled in the VM signal handler code though?  So while
> think these minidump could be very useful, I'm not sure this is a reason
> to have a classlib signal handler.
>
> -Mark.
>
> > On 2/9/07, Gregory Shimansky <gshimansky@gmail.com> wrote:
> > >
> > > Mark Hindess wrote:
> > > > I think we should go for the record of resurrecting a thread the
> most
> > > > times ;-)
> > > >
> > > > The current solution still compiles the hysig code.  However, I've
> > > > got a patch (windows and Linux but only tested on Linux) that adds a
> > > > flag to give the option to avoid the compilation of the hysig
> library
> > > > completely.  The default is to compile it but I'd actually like to
> > > > reverse that after some wider testing.
> > > >
> > > > Does this seem reasonable?
> > > >
> > > > I want to use this option because it means I can avoid porting the
> > > > signalling code to new architectures and platforms until we decide
> if we
> > > > are going to keep it.  At the moment, I think we probably should get
> rid
> > > > of it and let the VM handle signals.
> > > >
> > > > Gregory, why did you want it to be optional?  Do you use this
> option?
> > >
> > > The reason is quite simple. When VM crashes it is much easier to debug
> > > it right at the spot of the crash. On Windows it is done with Just In
> > > Time debugging facility, on Linux core dump is useful. DRLVM with can
> > > and does detect the condition when crash happens inside of VM and when
> > > it is ran with -XDassert_dialog=true (default) does not try to do
> > > anything intelligent like printing stack. This allows debugging at the
> > > spot of the crash.
> > >
> > > When launcher installs its own handler it catches the crash. Even
> though
> > > it can print registers and maybe some stack symbols, it is not as good
> > > as using full fledged debugger to analyze the problem.
> > >
> > > > On 10 January 2007 at 21:07, Gregory Shimansky <gshimansky@gmail.com
> >
> > > wrote:
> > > >> Tim Ellison wrote:
> > > >>> I'm going for the record of resurrecting the oldest thread ;-)
> > > >>>
> > > >>> Having this additional signal handler in the launcher is causing
> me
> > > pain
> > > >>> too, so unless there are objections now I'm going to go ahead
and
> > > >>> disable it by default, and have an option to enable it for those
> that
> > > want.
> > > >> +1
> > > >>
> > > >> Let's have it optional.
> > > >>
> > > >>> Ivan Volosyuk wrote:
> > > >>>> It seems that in cmain.c in function genericSignalHandler()
just
> > > >>>> removing abort() statement will cause default system handler
to
> > > >>>> execute pointing the exact place of fault right after printing
> all
> > > >>>> this useless crash info. I have no idea how to obtain property
> value
> > > >>>> in this place to make the abort() conditional. Anyway, I think
it
> > > >>>> would be much beneficial for developers to have crash by default.
> > > >>>> --
> > > >>>> Ivan
> > > >>>>
> > > >>>> On 9/22/06, Geir Magnusson Jr. <geir@pobox.com> wrote:
> > > >>>>> This can't be that hard.  Maybe a simple command-line
flag
> > > >>>>>
> > > >>>>>    -launcher:something
> > > >>>>>
> > > >>>>> Give it a wack and see what happens...
> > > >>>>>
> > > >>>>> geir
> > > >>>>>
> > > >>>>>
> > > >>>>> On Sep 22, 2006, at 1:29 PM, Ivan Volosyuk wrote:
> > > >>>>>
> > > >>>>>> Exactly. I would like to have a way to disable the
crash
> handler
> > > >>>>>> invoked in the call.
> > > >>>>>> It is quite painful to locate crashing place when
the crash
> handler
> > > >>>>>> enabled. Even setting breakpoint in the handler doesn't
help -
> > > stack
> > > >>>>>> at this place has number of system frames without
debug
> information
> > > >>>>>> which hide the actual problematic point.
> > > >>>>>> --
> > > >>>>>> Ivan
> > > >>>>>>
> > > >>>>>> On 9/22/06, Geir Magnusson Jr. <geir@pobox.com>
wrote:
> > > >>>>>>> Do you mean sig_protect in cmain.c?
> > > >>>>>>>
> > > >>>>>>> geir
> > > >>>>>>>
> > > >>>>>>> On Sep 22, 2006, at 12:22 PM, Ivan Volosyuk wrote:
> > > >>>>>>>
> > > >>>>>>>> Hi,
> > > >>>>>>>>
> > > >>>>>>>> While working on windows on DRLVM I introduced
some crash
> > > >>>>>>> situation. I
> > > >>>>>>>> found out that there are two active crash
handlers. One in
> > > >>>>>>> DRLVM, the
> > > >>>>>>>> other in launcher/classlib.
> > > >>>>>>>>
> > > >>>>>>>> I can disable DRLVM's one: -Dvm.assert_dialog=1
> > > >>>>>>>> But the launcher's crash handler still prevent
me to use
> > > >>>>>>> debugger to
> > > >>>>>>>> locate exact place of access violation in
VM code. Is it
> > > >>>>>>> possible to
> > > >>>>>>>> disable it somehow?
> > > >>>>
> ---------------------------------------------------------------------
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> > > >>>>
> > > >>>>
> > > >>
> > > >> --
> > > >> Gregory
> > > >>
> > > >
> > >
> > >
> > > --
> > > Gregory
> > >
> > >
> >
> > ------=_Part_30943_21988286.1171254458336--
> >
>
> --
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