Re: Windows crash / abort handling

On Wed, 6 Oct 2021, 03:30 Andres Freund, <andres(at)anarazel(dot)de> wrote:

> Hi,
>
>
> My first attempt was to try to use the existing crashdump stuff in
> pgwin32_install_crashdump_handler(). That's not really quite what I want,
> because it only handles postmaster rather than any binary, but I thought
> it'd
> be a good start. But outside of toy situations it didn't work for me.
>

Odd. It usually has for me, and definitely not limited to the postmaster.
But it will fall down for OOM, smashed stack, and other states where
in-process self-debugging is likely to fail.

>
> A bunch of debugging later I figured out that the reason neither the
> SetUnhandledExceptionFilter() nor JIT debugging works is that the
> SEM_NOGPFAULTERRORBOX in the
> SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX);
> we do in startup_hacks() prevents the paths dealing with crashes from being
> reached.
>

Right.

I patch this out when working on windows because it's a real pain.

I keep meaning to propose that we remove this functionality entirely. It's
obsolete. It was introduced back in the days where DrWatson.exe "windows
error reporting") used to launch an interactive prompt asking the user what
to do when a process crashed. This would block the crashed process from
exiting, making everything grind to a halt until the user interacted with
the
UI. Even for a service process.

Not fun on a headless or remote server.

These days Windows handles all this a lot more sensibly, and blocking crash
reporting is quite obsolete and unhelpful.

I'd like to just remove it.

If we can't do that I'd like to at least make it optional.

Alternatively we can generate "minidumps" [6], but that doesn't appear to
> be more
> helpful for CI purposes at least - all we'd do is to create a backtrace
> using
> the same tool. But it might be helpful for local development, to e.g.
> analyze
> crashes in more detail.
>

They're immensely helpful when a bt isn't enough, but BTs are certainly the
first step for CI use.