Re: Proposal: New LWLockmode LW_OWNER

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: "Jignesh K(dot) Shah" <J(dot)K(dot)Shah(at)Sun(dot)COM>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Proposal: New LWLockmode LW_OWNER
Date: 2008-06-06 18:15:04
Message-ID: 27394.1212776104@sss.pgh.pa.us
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Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Tom Lane wrote:
>> "Jignesh K. Shah" <J(dot)K(dot)Shah(at)Sun(dot)COM> writes:
>>> New Lock Mode Proposed: LW_EX_OWNER (input on better name will be
>>> appreciated).

> We do something like this in the sinval code -- see SIGetDataEntry.

Yeah, that analogy occurred to me later --- EX_OWNER would be a close
match to what sinval is doing. However, adding a third mode to LWLocks
would certainly introduce extra cycles into what is already a hotspot,
and one use-case that is already working fine without it doesn't seem
like much of an argument. (ProcArray isn't a use-case because of the
commit interlock problem, and I didn't see any other proposed uses
that weren't mere hand-waving.)

regards, tom lane

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