Re: (Java) Synchronizing multiple app servers through Oracle

On Dec 21, 1:35 am, Robert Klemme <shortcut..._at_googlemail.com> wrote:
> On Dec 21, 5:19 am, "Palooka" <nob..._at_nowhere.com> wrote:
>
>
>
>
>
> > "joel garry" <joel-ga..._at_home.com> wrote in message
>
> >news:a21025c6-99a0-4049-a975-188c77bbef28_at_d27g2000prf.googlegroups.com...
>
> > > On Dec 19, 12:05 pm, chrism..._at_gmail.com wrote:
> > >>  > > Typically the lock will last less than one second.
>
> > >> > I'd say that's pretty long.  How often will you - pardon, your
> > >> > application - acquire the lock and what's the general load pattern of
> > >> > the application?
>
> > >> Yes, it's not that short of a period of time, but unfortunately,
> > >> that's how long it takes to grab unique records.  Right now we have 2
> > >> app servers each hitting the database once per second and acquiring a
> > >> lock.  However, the number of app servers could grow to 10 or more.  I
> > >> wrote a multi-threaded test to simulate multiple servers, and found
> > >> that Oracle appears to have a problem when more than 10 locks are
> > >> acquired at the same time.  It seems to just give up and wait for the
> > >> timeout once too many have been acquired.  Is there a setting in
> > >> Oracle to handle more simultaneous locks?
>
> > > It kind of depends what exactly is going on.  Metalink Note:15476.1 is
> > > a basic description of locks and how to see what is locked.  Note:
> > > 402983.1 is a performance FAQ that includes how to check if the db is
> > > really hung.  The Performance manual in the doc set describes how to
> > > check what is really being waited for.  Views such as dba_lock and v
> > > $session_wait can really help, and don't discount some of the graphic
> > > tools available.
>
> > > If you are not using the default locking methods, you need to
> > > understand what you are doing and how to use the instrumentation
> > > available to understand it.  Once you understand the actual problem,
> > > you can fix it, if you haven't designed your strategy to be
> > > unfixable.  Asking for a setting for more simultaneous locks - well,
> > > you might want to review the Concepts manual on locking, you may have
> > > some misconceptions.
>
> > > Before you do any of that... when "oracle appears to have a
> > > problem..." are your cpu's going nuts?  Do you see very high latch
> > > waits?  What version and platform, exactly (10g isn't enough, we need
> > > something like 10.2.0.4), are you using?  What locks are you aquiring?
>
> > Joel is rightly suspicious that the wheel is being reinvented.
>
> Nitpick: I think he talks less about reinventing the wheel but rather
> about understanding concepts and what happens and apply the correct
> medicine - not something that you guess will help. :-)
>
> Kind regards
>
> robert

"I don't even know what I'm _talking_ about!" - Abbott and Costello, _Who's on First_

jg

--
@home.com is bogus.
http://www.phoenix5.org/humor/WhoOnFirst.html