Re: lwlocks and starvation - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: lwlocks and starvation
Date
Msg-id 200412020251.iB22pPn03517@candle.pha.pa.us
Whole thread Raw
In response to Re: lwlocks and starvation  (Neil Conway <neilc@samurai.com>)
Responses Re: lwlocks and starvation
List pgsql-hackers
Neil, where are we on this?  Should we add comments?  Add a TODO?  A patch?

---------------------------------------------------------------------------

Neil Conway wrote:
> 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
> 
> 

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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