Re: lwlocks and starvation - Mailing list pgsql-hackers

From Neil Conway
Subject Re: lwlocks and starvation
Date
Msg-id 1101963343.22124.190.camel@localhost.localdomain
Whole thread Raw
In response to Re: lwlocks and starvation  (Bruce Momjian <pgman@candle.pha.pa.us>)
Responses Re: lwlocks and starvation  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-hackers
On Wed, 2004-12-01 at 21:51 -0500, Bruce Momjian wrote:
> Neil, where are we on this?  Should we add comments?  Add a TODO?  A patch?

I'm not sure what the right resolution is. As I said, I don't think it's
wise to apply a patch that could have a significant impact on
performance without (a) testing its performance effect and/or (b) having
any evidence that the problem it addresses actually effects anyone in
the real world. I'll try to run some benchmarks when I get a chance.

I wrote up most of a patch to implement the "wake up all shared wakers
on LWLockRelease()" behavior to see how that would change performance,
but the patch has a subtle bug in it that I can't seem to find (I've
attached it -- comments welcome).

Certainly if we decide to leave things as they are I think we ought to
document why the behavior is intentional, but I don't think we have
enough data to make that decision yet.

-Neil


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