Re: How to handle deadlocks ?
Date: 1996/06/10
Message-ID: <4piaf3$55r_at_murrow.corp.sgi.com>#1/1
In article <4pi4u1$5i_at_chleuasme.francenet.fr>, cberthet_at_MicroNet.fr writes:
> In article <DsszAL.7MC_at_world.std.com>, bgw_at_world.std.com (Bruce G Wilson) says:
> >
> >
> >I've been on a couple of contracting jobs where the client uses
> >Sybase (4.9 and System 10). At each place, there were occasions
> >where they had problems with deadlock: two processes trying to
> >allocate two resources in opposite order. It struck me that part
> >of the reason why this is such a problem is that locks are taken
> >(and escalated) implicitly in Sybase, so that it's difficult from
> >a superficial read of the code to tell when a lock is being taken
> >and where the conflict might be occurring. I guess I'm kind of
> >surprised to find that locks can't be taken explicitly; with this,
> >it would be made clear in the code where the locks are being taken
> >and might make it easier to determine where the problem is.
> >
> >I'm wondering, what kinds of techniques are used in "standard"
> >practice with Sybase to detect/prevent deadlocks ? Do IS
> >organizations establish rules for accessing the database, like,
> >"always do an update to table A before doing an update to table B" ?
> >It strikes me that that's really the only way to control this
> >sort of problem.
> >
> >I can't imagine that other databases (Oracle, Informix) don't also
> >have this kind of problem. How are deadlocks handled in these ?
> >
>
> Ordering access to the objects in your database is the best way
> to REDUCE dealock, keep transactions as short as possible too.
> To understand why you have a deadlock you can activate two traceflags,
> they will generate a stack in your errorlog with all the details
> (store proc, pages..) about your deadlock.
> Your applications must presume a deadlock can occurs anywhere, thus
> code deadlock processing.
See Sybase FAQ for those traceflags - see .sig.
Pablo Sanchez | Ph # (415) 933.3812 Fax # (415) 933.2821 pablo_at_sgi.com | Pg # (800) 930.5635 -or- pablo_p_at_corp.sgi.com ===============================================================================I am accountable for my actions. http://reality.sgi.com/pablo [ /Sybase_FAQ ] Received on Mon Jun 10 1996 - 00:00:00 CEST