| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Neil Conway <neilc(at)samurai(dot)com> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: lwlocks and starvation |
| Date: | 2004-11-24 12:34:26 |
| Message-ID: | 200411241234.iAOCYR104015@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
Neil Conway wrote:
> Bruce Momjian wrote:
> > My guess is the existing behavior was designed to allow waking of
> > multiple waiters _sometimes_ without starving of exclusive waiters.
>
> Well, I think the current algorithm *does* allow starvation, at least in
> some situations. Consider a workload in which a new shared reader
> arrives every 50 ms, and holds the lock for, say, 500 ms. If an
> exclusive waiter arrives, they will starve with the current algorithm.
I thought the new readers will sit after the writer in the FIFO queue so
the writer will not starve.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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