Re: Wait free LW_SHARED acquisition - v0.2

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Peter Geoghegan <pg(at)heroku(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Wait free LW_SHARED acquisition - v0.2
Date: 2014-10-08 17:13:33
Message-ID: CA+TgmoY9+bE6Zpz9goRNHnOXsXEw51jv-eptK+AdoLL4rrmhHQ@mail.gmail.com
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On Wed, Oct 8, 2014 at 8:47 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> I don't see that as being relevant. The difference is an instruction or
> two - in the slow path we'll enter the kernel and sleep. This doesn't
> matter in comparison.
> And the code is *so* much more readable.

I find the slist/dlist stuff actually quite difficult to get right
compared to a hand-rolled linked list. But the really big problem is
that the debugger can't do anything useful with it. You have to work
out the structure-member offset in order to walk the list and manually
cast to char *, adjust the pointer, and cast back. That sucks.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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