| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Staale Smedseng <Staale(dot)Smedseng(at)Sun(dot)COM> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Why are we waiting? |
| Date: | 2008-02-06 14:48:45 |
| Message-ID: | 1202309325.29242.27.camel@ebony.site |
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| Lists: | pgsql-hackers |
On Wed, 2008-02-06 at 15:30 +0100, Staale Smedseng wrote:
> On Mon, 2008-02-04 at 19:46, Simon Riggs wrote:
> > We've got various facilities now for looking at LWLock waits, but I'd
> > like to have more information about the *reasons* for lock waits.
> >
> > I know its possible to get backtraces in Dtrace at various tracepoints
> > but that can be fairly hard to interpret.
Thanks for this Staale.
> Lock Id Mode Count
> ProcArrayLock Shared 1821
> ProcArrayLock Exclusive 49762
>
> Lock Id Mode Combined Time (ns)
> ProcArrayLock Shared 31114676303
> ProcArrayLock Exclusive 888356047549
Which looks like a mean service time of 17ms for X lock waiters.
What is the frequency distribution of lock wait time on ProcArrayLock?
Does the distribution vary over time?
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com
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