Re: Has anyone done any scalability work on dbms_lock?

On a light-weight test on 8.1.7.4 at 700MHz on W2000 -

About 15,000 request/release per second

    if you are using an ID

About 8,000 request/release per second

    if you are using a pre-allocated lock handle

About 800 request/release per second

    if you have to allocate_unique on every request.

Bear in mind that each request or release will hit the enqueue latch a couple of times, so you could get contention for the latch in the two high-speed options. (Forget the low-speed option, allocate_unique does a commit in mid-stream, which you might be able to hide with a recursive transaction - but the overheads are extreme).

Bottom line - for high-speed OLTP type of work, I don't think you will get away with more than a dozen request/release cycles per transaction.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, January 21, 2004 12:49 PM

> As in: does it present an inherent or hidden performance
> problem when a lot of sessions try to lock/release the same
> lock? Or how many lock/release per second. Or some other
> idea of how efficient it is?
>
> Need to use it in a design, but not sure of any potential
> performance hits or scalability issues. Any ideas?
>
> TIA.
> Cheers
> Nuno Souto
> nsouto_at_optusnet.com.au

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