On Tue, 2006-05-02 at 07:04 -0400, Joseph B. Ottinger wrote:
> On Tue, 2 May 2006, Binod wrote:
>
> > Joseph B. Ottinger wrote:
> >
> >> Refreshing the context: I'm writing an app that uses MDBs and JPA (and a
> >> timer) to create lots and lots of data on a regular basis (it crawls a set
> >> of pages and logs changes.)
> >>
> >> I set up the DB connection pool to have 64 connections maximum; however, I
> >> find that I'm getting a max pool size used message an awful lot.
> >
> > And how many users you have?
>
> Hrm, well... hard to say how many messages are being pumped through the
> system at any given time. It can certainly skyrocket, so I can imagine
> it's pretty high.
>
> > 64 max-pool-size means that only a maximum of 64 threads can use pool
> > simultaneously.
> >
> > Also, if one thread need more than one connection at the same time, then the
> > sizing will be different.
> > This can happen if there is a
> > startTx-useConnection->suspendTx->startNewTx->useConnection->endNewTx->endTx
> > kind of a scenario in an application.
>
> Well, there are cases where a single MDB uses two DAOs, each of which has
> its own EntityManager. Apart from that, I haven't set any transaction
> attributes at all.
>
> > In the first look, it look like you are having a sizing problem.
>
> That's what I thought, too, except running under a situation where you
> shouldn't have a ton of connections being created *also* fired off the
> same connection count. Further, once I get the out-of-connections message,
> the appserver never recovers -- a bigger problem, in my opinion.
I am not sure how it happens. AFAIK, when conn. pool could not provide a
connection, max-wait-time expired exception is thrown to the application
and as a result, rollback will happen.
Further conn. requests will work fine.
Is it possible for you to provide the source of your application, so
that we can get more details ?
-Jagadish
> > - Binod.
> >
> >>
> >> Now, I'll gladly admit that I'm hammering the DB on update - a single web
> >> page that changes can generate 300+ new entities (or updates to existing
> >> entities) or more, actually. I haven't actually tested boundaries yet,
> >> because the app's barely in smoke-testing stage.
> >>
> >> However, I'm not using *any* connections manually - everything's going
> >> through JPA, so connection allocations should be fairly short-lived. Am I
> >> seeing something incorrect in action?
> >>
> >> -----------------------------------------------------------------------
> >> Joseph B. Ottinger http://enigmastation.com
> >> Editor, http://www.TheServerSide.com joeo@enigmastation.com
> >>
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> -----------------------------------------------------------------------
> Joseph B. Ottinger http://enigmastation.com
> Editor, http://www.TheServerSide.com joeo@enigmastation.com
>
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