Re: semaphore usage "port based"?

From: Vivek Khera <vivek(at)khera(dot)org>
To: freebsd-stable <freebsd-stable(at)freebsd(dot)org>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: semaphore usage "port based"?
Date: 2006-04-03 18:22:23
Message-ID: A1072D0B-7416-493C-8CCC-C9126134A9B3@khera.org
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On Apr 3, 2006, at 12:37 PM, Tom Lane wrote:

> semaphore keys on each cycle of life, so you'd have to get fooled by
> chance coincidence of existing PIDs every time over many cycles to
> have a severe resource-leakage problem. (BTW, Marc, that's the reason
> for *not* randomizing the key selection as you suggested.)

Seems to me the way around this with minimal fuss is to add a flag to
postgres to have it start at different points in the ID sequence.
So pg#1 would start at first position, pg#2 second ID position, etc.
then just hard-code an "instance ID" into the startup script for each
pg. No randomization make it easier to debug, and unique IDs make it
avoid clashes under normal cases.

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