[Rd] R 4.0.2 64-bit Windows hangs

[Jeroen Ooms]

On Sat, Aug 22, 2020 at 9:10 PM Tomas Kalibera <tomas.kalibera using gmail.com> wrote:
>
> On 8/22/20 8:26 PM, Tomas Kalibera wrote:
> > On 8/22/20 7:58 PM, Jeroen Ooms wrote:
> >> On Sat, Aug 22, 2020 at 8:39 AM Tomas Kalibera
> >> <tomas.kalibera using gmail.com> wrote:
> >>> On 8/21/20 11:45 PM, m19tdn+9alxwj7d2bmk--- via R-devel wrote:
> >>>> Ah yes, this is related. I reported v2010 below, but it looks like
> >>>> I was updated to this Insider Build overnight without my knowledge,
> >>>> and conflated it with the new installation R v4 this morning.
> >>>>
> >>>> I will continue to look into the issue with the methods Tomas
> >>>> mentioned.
> >>> It is interesting that a rare 5 years old problem would re-appear on
> >>> current Insider builds. Which build of Windows are you running exactly?
> >>> I've seen another report about a crash on 20190.1000. It'd be nice to
> >>> know if it is present also in newer builds, i.e. in 20197.
> >> I installed the latest 20197 build in a vm, and I can indeed reproduce
> >> this problem.
> >>
> >> What seems to be happening is that R triggers an infinite recursion in
> >> Windows unwinding mechanism, and eventually dies with a stack
> >> overflow. Attached a backtrace of the initial 100 frames of the main
> >> thread (the pattern in the top ~30 frames continues forever).
> >>
> >> The microsoft blog doesn't mention anything related to exception
> >> handling has changed in recent versions:
> >> https://docs.microsoft.com/en-us/windows-insider/at-home/active-dev-branch
> >>
> >
> > Thanks, unfortunately that does not ring any bells (except below), I
> > can't guess from this what is the underlying cause of the problem.
> > There may be something wrong in how we use setjmp/longjmp or how
> > setjmp/longjmp works on Windows.
> >
> > It reminds me of a problem I've been debugging few days ago, when
> > longjump implementation segfaults on Windows 10 (recent but not
> > Insider build) probably soon after unwinding the stack, but only with
> > GCC 10 / MinGW 7 and only in one of the no-segfault tests, and only
> > with -03 (not -O2, not with with -O3 -fno-split-loops). The problem
> > was sensitive to these optimization options interestingly on the call
> > site of long jump (do_abs), even when it was not an immediate caller
> > of the longjump. I've not tracked this down yet, it will require
> > looking at the assembly level, and I was suspecting a compiler error
> > causing the compiler to generate code that messes with the stack or
> > registers in a way that impacts the upcoming jump. But now as we have
> > this other problem with setjmp/logjmp, the compiler may not be the top
> > suspect anymore.
> >
> > I may not be able to work on this in the next few days or a week, so
> > if anyone gets there first, please let me know what you find out.
>
> Btw could you please try out if the UCRT build of R crashes as well in
> the Insider Windows build ?

Yes, it hangs in exactly the same way, except that the backtrace shows

 ucrtbase!.intrinsic_setjmpex () from C:\WINDOWS\System32\ucrtbase.dll

Instead of msvcrt!_setjmpex (as expected of course).