Re: Shave a few instructions from child-process startup sequence

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Cc: Gurjeet Singh <gurjeet(at)singh(dot)im>, PGSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Shave a few instructions from child-process startup sequence
Date: 2013-11-04 05:20:25
Message-ID: 20224.1383542425@sss.pgh.pa.us
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Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
> On Fri, Nov 1, 2013 at 9:50 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I think this is adding fragility for absolutely no meaningful savings.
>> The existing code does not depend on the assumption that the array
>> is filled consecutively and no entries are closed early.

> As I could see, it appears to me that code in ServerLoop and
> initMasks is already dependent on it, if any socket is closed out of
> order, it can break the logic in these API's. Do me and Gurjeet are
> missing some point here?

It's not hard to foresee that we might have to fix those assumptions
someday. If we were buying a lot by adding a similar assumption here,
it might be worth doing even in the face of having to revert it later.
But we're not buying much. A few instructions during postmaster shutdown
is entirely negligible.

regards, tom lane

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