DBMS_LOCK manipulates the same enqueue mechanism that Oracle uses for just
about everything. Same as every other type of lock shown in V$LOCK, just
type = "UL".
Thus, any problems in DBMS_LOCK would be shared by just about every facet of
session-level concurrency in the RDBMS...
on 1/21/04 5:4
I came across a very nice example a while ago
where there were 4 concurrent sessions feeding
data into a holding table, and one session consuming
from the table.
The rules said that the consumer could not run
while the producers were loading the table, but
multiple producers were allowed to run.
Well, I don't know about anyone else, but I make use of it to synchronize data upload
programs for our testers. Can't have two instances of the upload program processing
the same tester, they'd duplicate data. Anyhow, we normally run 4 instances of this
program & the dbms_lock package works ab
Just remember these words about global contexts ... 'doesn't work correctly in RAC'
...
A global context is "global" only within instance ... not across.
Raj
Rajendra dot Jamadagni at nospamespn dot com
All Views e
> Jonathan Lewis <[EMAIL PROTECTED]> wrote:
>
> Sounds like you just need each user to call allocate_unique
> on startup to get a group-specific handle, then do a
> request in exclusive mode before doing the job and
> a release on completion. Users will then naturally queue
> and resume with min
Hmm, that's actually a very good idea.
It might actually do the job here. Thanks.
Nuno Souto
[EMAIL PROTECTED]
> Jamadagni, Rajendra <[EMAIL PROTECTED]> wrote:
>
> if it is single instance you could also use global application
> contexts ... (alas they don't work in RAC across node) ...
>
--
Pl
Note in-line
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The educated person is not the person
who can answer the questions, but the
person who can question the answers -- T. Schick Jr
Next public appearance2:
March 2004 Hotsos Symposium - Keynote
March 2004 Charlotte NC -
if it is single instance you could also use global application contexts ... (alas they
don't work in RAC across node) ...
Raj
Rajendra dot Jamadagni at nospamespn dot com
All Views expressed in this email are strictl
- Original Message -
> nuno-- what level are you trying to scale it to?
Not much. A few hundred users, maybe 20 or so may
need the lock. However, this app may explode in
# users, so I want to make sure I'm not creating
a "monster".
> how long will you hold the locks?
only long enough
- Original Message -
> 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
sounds plenty good to me. Thanks a lot.
> Bear in mind that each request or release will hit the
> enqueue latch a couple of times, s
- Original Message -
> > Or how many lock/release per second. Or some other
> > idea of how efficient it is?
> Depends on the work done between acquiring the lock and releasing it.
Not really. I'm asking how many lock/releases can be done
before the thing starts putting a serious load
book, but I like it)... there is a
nifty wrapper for DBMS_LOCK. I based my code off of that.
>
> From: "Carel-Jan Engel" <[EMAIL PROTECTED]>
> Date: 2004/01/21 Wed AM 08:24:25 EST
> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
> Subje
i think expert one on one has some comments on it. Its in a section referring to
building your own insert locks. So if a table is locked, the user gets notified.
I read the book last year.
>
> From: "Nuno Souto" <[EMAIL PROTECTED]>
> Date: 2004/01/21 Wed AM 07:49:25 EST
> To: Multiple recipien
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 req
> As in: does it present an inherent or hidden performance
> problem when a lot of sessions try to lock/release the same
> lock?
Will serialize perfectly!
> Or how many lock/release per second. Or some other
> idea of how efficient it is?
Depends on the work done between acquiring the lock and re
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