Re: hung backends stuck in spinlock heavy endless loop

On 2015-01-13 15:49:33 -0800, Peter Geoghegan wrote:
> On Tue, Jan 13, 2015 at 3:21 PM, Andres Freund <andres@2ndquadrant.com> wrote:
> > My guess is rather that it's contention on the freelist lock via
> > StrategyGetBuffer's. I've seen profiles like this due to exactly that
> > before - and it fits to parallel loading quite well.
> 
> I'm not saying you're wrong, but the breakdown of _bt_moveright()
> relative to _bt_relandgetbuf() calls seems a bit fishy to me.

The hierarchical profile definitely doesn't look like my guess was
right.

> I don't remember seeing _bt_moveright()  or _bt_compare() figuring so
> prominently, where _bt_binsrch() is nowhere to be seen. I can't see a
> reference to _bt_binsrch() in either profile.

Well, we do a _bt_moveright pretty early on, so that actually might be
cache misses we're primarily seing.

Greetings,

Andres Freund

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