[Rd] R 4.0.2 64-bit Windows hangs

[Tomas Kalibera]

On 8/22/20 9:33 PM, Jeroen Ooms wrote:
> 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).

Thanks. I found what is causing the problem I observed with GCC10/stock 
Windows 10, I expect this is the same one as in the Insider build.
I will investigate further,

Tomas