| From: | Neil Conway <neilc(at)samurai(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: lwlocks and starvation |
| Date: | 2004-11-25 06:04:16 |
| Message-ID: | 1101362656.12045.74.camel@localhost.localdomain |
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| Thread: | |
| Lists: | pgsql-hackers |
On Wed, 2004-11-24 at 23:30 -0500, Tom Lane wrote:
> It is not a 100% solution because it does not
> cover the case where a waiting exclusive locker is released, then a new
> shared locker arrives at the lock before the exclusive locker is given
> any cycles to acquire the lock. However I don't see any cure for the
> latter problem that's not worse than the disease
Yeah, I don't think this is a problem -- eventually the exclusive waiter
will win the coin flip anyway.
> On the other hand we might consider that this isn't a big problem and
> just leave things as they are. We haven't seen any indication that
> starvation is a real problem in practice, and so it might be better to
> avoid extra trips through the kernel scheduler.
Yes, I'm a little concerned about applying a patch to address what is,
so far, an entirely academic concern -- especially if it might hurt
performance.
-Neil
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