Re: "stuck spinlock"

On 2013-12-13 15:49:45 -0600, Merlin Moncure wrote:
> On Fri, Dec 13, 2013 at 12:32 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > On Fri, Dec 13, 2013 at 11:26 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> And while we're on the subject ... isn't bgworker_die() utterly and
> >> completely broken? That unconditional elog(FATAL) means that no process
> >> using that handler can do anything remotely interesting, like say touch
> >> shared memory.
> >
> > Yeah, but for the record (since I see I got cc'd here), that's not my
> > fault. I moved it into bgworker.c, but it's been like that since
> > Alvaro's original commit of the bgworker facility
> > (da07a1e856511dca59cbb1357616e26baa64428e).
>
>
> Is this an edge case or something that will hit a lot of users?
> Arbitrary server panics seems pretty serious...

Is your question about the bgworker part you're quoting or about the
stuck spinlock stuff? I don't think the bgworker bug is too bad in
practice but the one in handle_sig_alarm() stuff certainly is.

I think while it looks possible to hit problems without statement/lock
timeout, it's relatively unlikely that those are hit in practice.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services