Re: Signaling of waiting for a cleanup lock?

On 13 April 2014 16:44, Andres Freund <andres@2ndquadrant.com> wrote:
> On 2014-04-12 17:40:34 -0400, Robert Haas wrote:
>> On Fri, Apr 11, 2014 at 10:28 AM, Andres Freund <andres@2ndquadrant.com> wrote:
>> > VACUUM sometimes waits synchronously for a cleanup lock on a heap
>> > page. Sometimes for a long time. Without reporting it externally.
>> > Rather confusing ;).
>> >
>> > Since we only take cleanup locks around vacuum, how about we report at
>> > least in pgstat that we're waiting? At the moment, there's really no way
>> > to know if that's what's happening.
>>
>> That seems like a pretty good idea to me.
>
> What I am not sure about is how... It's trivial to set
> pg_stat_activity.waiting = true, but without a corresponding description
> what the backend is waiting for it's not exactly obvious what's
> happening. I think that's better than nothing, but maybe somebody has a
> glorious better idea.

pg_stat_activity.waiting = true

can be done in 9.4 easily enough. Any objections to doing this?

Easy to set the ps message also

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