Re: POC: GUC option for skipping shared buffers in core dumps

On 2020-Feb-10, Andres Freund wrote:

> Hi,
>
> On 2020-02-10 17:31:47 -0300, Alvaro Herrera wrote:
> > Yeah. Maybe we should file bug reports against downstream packages to
> > include a corefilter tweak.
>
> Hm, I'm not sure that's a reasonable way to scale things. Nor am I
> really sure that's the right granularity.

Hah. This argument boils down to saying our packagers suck :-)

> > I don't know how easy is it to teach systemd to do this on its service
> > files.
>
> Well, you could just make it part of the command that starts the
> server. Not aware of anything else.

I tried to do that, but couldn't figure out a clean way, because you
have to do it after the fact (not in the process itself). Maybe it's
possible to have pg_ctl do it once postmaster is running.

> > FWIW I've heard that some people like to have shmem in core files to
> > improve debuggability, but it's *very* infrequent.
>
> Oh, I pretty regularly want that. If you're debugging anthying that
> includes locks, page accesses, etc, it's pretty hard to succeed without?

yyyyeah kinda, I guess -- I don't remember cases when I've wanted to do
that in production systems.

> > But maybe we should have a way to disable the corefiltering.
>
> There should, imo. That's why I was wondering about making this a GUC
> (presumably suset).

Not really sure about suset ... AFAIR that means superuser can SET it;
but what you really care about is more like ALTER SYSTEM, which is
SIGHUP unless I misremember.

--
Álvaro Herrera https://www.2ndQuadrant.com/
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