Re: Latch for the WAL writer - further reducing idle wake-ups.

Peter Geoghegan <peter(at)2ndquadrant(dot)com> writes:
> On 8 May 2012 22:35, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Now that I've actually read the patch, rather than just responding to
>> your description of it, I find myself entirely unhappy with the proposed
>> changes in the walwriter's sleep logic. You have introduced race
>> conditions (it is NOT okay to reset the latch somewhere below the top of
>> the loop)

> Yes, there is some checking of flags before the potential ResetLatch()
> call, which may be acted on. The code there is almost identical to
> that of the extant bgwriter code.

Um, yes, I noticed that shortly after sending my previous message.
I'm pretty unhappy about the current state of the bgwriter loop, too.
I rather wonder whether that coding explains the "postmaster failed to
shut down" errors that we've been seeing lately in the buildfarm.
Not noticing a shutdown signal promptly would go a long way towards
explaining that.

regards, tom lane