Re: Dynamic LWLock tracing via pg_stat_lwlock (proof of concept)

* Craig Ringer (craig(at)2ndquadrant(dot)com) wrote:
> > The patch https://commitfest.postgresql.org/action/patch_view?id=885
> > (discussion starts here I hope -
> > http://www.postgresql.org/message-id/4FE8CA2C.3030809@uptime.jp)
> > demonstrates performance problems; LWLOCK_STAT, LOCK_DEBUG and
> > DTrace-like approach are slow, unsafe for production use and a bit
> > clumsy for using by DBA.
>
> It's not at all clear to me that a DTrace-like (or perf-based, rather)
> approach is unsafe, slow, or unsuitable for production use.

I've certainly had it take production systems down (perf, specifically),
so I'd definitely consider it "unsafe". I wouldn't say it's unusable,
but it's certainly not what we should have as the end-goal for PG.

Thanks,

Stephen