Re: exposing wait events for non-backends (was: Tracking wait event for latches)

On Thu, Mar 23, 2017 at 1:24 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> I mean, your argument boils down to "somebody might want to
> deliberately hide things from pg_stat_activity". But that's not
> really a mode we support in general, and supporting it only for
> certain cases doesn't seem like something that this patch should be
> about. We could add an option to BackgroundWorkerInitializeConnection
> and BackgroundWorkerInitializeConnectionByOid to suppress it, if it's
> something that somebody wants, but actually I'd be more inclined to
> think that everybody (who has a shared memory connection) should go
> into the machinery and then security-filtering should be left to some
> higher-level facility that can make policy decisions rather than being
> hard-coded in the individual modules.
>
> But I'm slightly confused as to how this even arises. Background
> workers already show up in pg_stat_activity output, or at least I sure
> think they do. So why does this patch need to make any change to that
> case at all?

When working on a couple of bgworkers some time ago, I recalled that
they only showed up in pg_stat_activity only if calling
pgstat_report_activity() in them. Just looking again, visibly I was
mistaken, they do indeed show up when if WaitLatch() or
pgstat_report_activity() are not used. Please let me discard that
remark.
--
Michael