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From Rodney Waldhoff <rwaldh...@apache.org>
Subject Re: Pool project still active
Date Thu, 24 Jul 2003 23:57:34 GMT
IIRC, setting the max active property to a non-positive value will allow
the client to borrow an unlimited number of objects.  Setting the max
active property to a positive value will constrain the number of objects
that may be "borrowed but not yet returned" at the same time.

Hence if you set max active to some number smaller than the number of
clients trying to concurrently use objects borrowed from the pool, then
some of them are going to have to wait for the others to return objects
before they can proceed.

For example, suppose you set maxActive to 5, and have some clients running
the following loop:

for(;;) {
 Object obj = null;
 try {
   obj = pool.borrowObject();
   // do something with obj that takes a little while
 } finally {
   if(null != obj) { pool.returnObject(obj); }
 }
}


if the number of clients concurrently executing this loop is less than or
equal to 5, then the no one will block waiting on the pool.borrowObject
call.

If the number of clients concurrently executing this loop is greater than
5, then some of them must block on the pool.borrowObject call until one of
the five "active" objects is returned via the call to pool.returnObject.
This will most definitely have an impact on performance, by design.  When
configured in this way the pool is essentially acting as a bottleneck
(some might say throttle) on the number of clients concurrently using some
shared resource(s).

If this explanation is way off, perhaps you can provide more detail on
your test case.

- Rod <http://radio.weblogs.com/0122027/>

On Thu, 24 Jul 2003, Prashanth Adhikari wrote:

>
>
> Could you tell what this bug was? We are having an issue with the Torque
> connection pooling where if we set defaultMaxActive to anything other than
> -1 we see poor performance in our load tests. If you know what this bug was
> plese let me know.
> Thanks
> Prashanth
>
> >From: Chad La Joie <clajoie@vt.edu>
> >Reply-To: "Jakarta Commons Users List" <commons-user@jakarta.apache.org>
> >To: commons-user@jakarta.apache.org
> >Subject: Pool project still active
> >Date: Tue, 22 Jul 2003 09:07:17 -0400
> >
> >Is the Pool project still active?  I noticed a bug dealing with the max
> >active connection behavior that was patched about a year ago, but no
> >release was made incoporating that change.  Is there any activity in that
> >group, and if so could you please releae a 1.0.2 release that contains this
> >and other bug fixes, or comment on whether the nightly builds are
> >production quality.  Thanks.
> >--
> >Chad La Joie
> >Project Manager                (540) 231-6853
> >Middleware Services            http://www.middleware.vt.edu
> >
> >
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