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From: hokey@plus5.UUCP (Hokey)
Newsgroups: net.database
Subject: Re: locks
Message-ID: <854@plus5.UUCP>
Date: Sun, 15-Sep-85 22:50:22 EDT
Article-I.D.: plus5.854
Posted: Sun Sep 15 22:50:22 1985
Date-Received: Tue, 17-Sep-85 04:46:26 EDT
References: <10185@ucbvax.ARPA> <5909@utzoo.UUCP> <10233@ucbvax.ARPA> <341@harvard.ARPA> <2170@ukma.UUCP> <788@masscomp.UUCP>
Reply-To: hokey@plus5.UUCP (Hokey)
Organization: Plus Five Computer Services, St. Louis, MO
Lines: 19

The semaphores provided in SysV don't implement a queue, though.  A test
program was posted a while ago which shows that the semaphores implement
a *stack*!  Just think of the possibilities... The first in line is the
last in line!

Somebody (I forget who) at AT&T pointed out that all that was needed to
fix this was to change the code which puts processes awaiting semaphores
to sleep.  I do not know if this has been fixed, yet.

Since we have only recently begun seeing net.database in a consistent
fashion, I don't know if the issues surrounding file vs. record locks
has been fully beaten up.  There are definitely needs for both, depending
on the application.  I am told that implementing record locks in a
distributed environment is Nasty (Hi Clem!).

I am almost sorry I missed all the discussion on promotable locks.
-- 
Hokey           ..ihnp4!plus5!hokey
		  314-725-9492


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