"joel garry" <joel-garry_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.
Palooka
Received on Thu Dec 20 2007 - 22:19:26 CST
