Re: "stuck spinlock" - Mailing list pgsql-hackers

From Andres Freund
Subject Re: "stuck spinlock"
Date
Msg-id 20131214122025.GB25520@awork2.anarazel.de
Whole thread Raw
In response to Re: "stuck spinlock"  (Merlin Moncure <mmoncure@gmail.com>)
Responses Re: "stuck spinlock"
List pgsql-hackers
On 2013-12-13 15:49:45 -0600, Merlin Moncure wrote:
> On Fri, Dec 13, 2013 at 12:32 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> > On Fri, Dec 13, 2013 at 11:26 AM, Tom Lane <tgl@sss.pgh.pa.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



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