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Re: Sync Rep and shutdown Re: Sync Rep v19

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Yeb Havinga <yebhavinga(at)gmail(dot)com>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Sync Rep and shutdown Re: Sync Rep v19
Date: 2011-03-18 17:15:25
Message-ID: 1300468525.18619.15952.camel@ebony (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, 2011-03-17 at 09:33 -0400, Robert Haas wrote:

> Thanks for the review!

Lets have a look here...

You've added a test inside the lock to see if there is a standby, which
I took out for performance reasons. Maybe there's another way, I know
that code is fiddly.

You've also added back in the lock acquisition at wakeup with very
little justification, which was a major performance hit.

Together that's about a >20% hit in performance in Yeb's tests. I think
you should spend a little time thinking how to retune that.


I see handling added for ProcDiePending and QueryCancelPending directly
into syncrep.c without any comments in postgres.c to indicate that you
bypass ProcessInterrupts() in some cases. That looks pretty hokey to me.

SyncRepUpdateSyncStandbysDefined() is added into walwriter, which means
waiters won't be released if we do a sighup during a fast shutdown,
since the walwriter gets killed as soon as that starts. I'm thinking
bgwriter should handle that now.

-- 
 Simon Riggs           http://www.2ndQuadrant.com/books/
 PostgreSQL Development, 24x7 Support, Training and Services
 


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