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From Aman Nanner/MxI Technologies <aman.nan...@mxi.com>
Subject Re: Sharing resources in an MDB
Date Thu, 26 Apr 2007 18:00:13 GMT
So the solution you proposed seems to work with one caveat.  It does limit
the MDB to only one instance, and in that sense it works.  However, if
another JMS message is received on the queue while the MDB is still
processing the last message, a synchronization error occurs:

Caused by:
edu.emory.mathcs.backport.java.util.concurrent.RejectedExecutionException
      at
edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(
ThreadPoolExecutor.java:1519)
      at
edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.reject(
ThreadPoolExecutor.java:407)
      at
edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.execute(
ThreadPoolExecutor.java:880)
      at org.apache.geronimo.pool.ThreadPool.execute(ThreadPool.java:201)
      at org.apache.geronimo.pool.ThreadPool.execute(ThreadPool.java:173)
      at
org.apache.geronimo.pool.ThreadPool$$FastClassByCGLIB$$a77708d8.invoke(<generated>)
      at net.sf.cglib.reflect.FastMethod.invoke(FastMethod.java:53)
      at org.apache.geronimo.gbean.runtime.FastMethodInvoker.invoke(
FastMethodInvoker.java:38)
      at org.apache.geronimo.gbean.runtime.GBeanOperation.invoke(
GBeanOperation.java:122)
      at org.apache.geronimo.gbean.runtime.GBeanInstance.invoke(
GBeanInstance.java:820)
      at org.apache.geronimo.gbean.runtime.RawInvoker.invoke(
RawInvoker.java:57)
      at org.apache.geronimo.kernel.basic.RawOperationInvoker.invoke(
RawOperationInvoker.java:35)
      at org.apache.geronimo.kernel.basic.ProxyMethodInterceptor.intercept(
ProxyMethodInterceptor.java:96)
      at
org.apache.geronimo.pool.GeronimoExecutor$$EnhancerByCGLIB$$b29ee60a.execute(<generated>)
      at
org.apache.geronimo.connector.work.pool.ScheduleWorkExecutor.doExecute(
ScheduleWorkExecutor.java:36)
      at
org.apache.geronimo.connector.work.GeronimoWorkManager.executeWork(
GeronimoWorkManager.java:196)
      at
org.apache.geronimo.connector.work.GeronimoWorkManager.scheduleWork(
GeronimoWorkManager.java:182)
      at
org.apache.geronimo.connector.work.GeronimoWorkManager$$FastClassByCGLIB$$907eef28.invoke(<generated>)



David Jencks <david_jencks@yahoo.com> wrote on 04-25-2007 11:35:59 AM:

>
> On Apr 25, 2007, at 8:14 AM, ananner wrote:
>
> >
> > I also have a requirement to limit a certain MDB to a maximum of one
> > instance, but I am a bit confused as to your response.  Are you
> > saying that
> > I should put a pool size limit on the <outbound-resourceadapter> which
> > defines the Connection Factory that my MDB subscribes to?
>
> The ResourceAdapter instance gets a BootstrapContext instance when
> its started, and the BootstrapContext basically includes a thread
> pool.  So if you give it a thread pool with only one thread....
>
> In geronimo you specify which thread pool to use with this part:
>
>              <workmanager>
>                  <gbean-link>DefaultWorkManager</gbean-link>
>              </workmanager>
>
>
> So you could include a thread pool:
>
>      <gbean name="SingleThreadPool"
> class="org.apache.geronimo.pool.ThreadPool">
>          <attribute name="keepAliveTime">5000</attribute>
>          <attribute name="poolSize">1</attribute>
>          <attribute name="poolName"> SingleThreadPool </attribute>
>      </gbean>
>
> and use it:
>
>              <workmanager>
>                  <gbean-link>SingleWorkManager</gbean-link>
>              </workmanager>
>
> This is a horrible solution because you have to set up a resource
> adapter instance for each mdb that needs its size limited in this
> way.  Hopefully there's a way to restrict the mdb pool size that I
> don't know about.
>
> BTW, I recall hearing James Strachan talk about message groups.  If
> your requirements are that you get sets of messages that, within the
> set, must be processed in order rather than all messages must be
> processed in order you might be able to introduce some concurrency by
> using message groups.
>
>
> Hope this helps
> david jencks
>
> >
> > Thanks,
> > Aman
> >
> >
> > djencks wrote:
> >>
> >>
> >> It might possibly work for activemq if you don't use any
> >> transactions, but if you use transactions I would expect it to
> >> completely break and give pretty random behavior.  I don't think
> >> there's any reason to expect it to work even without transactions.
> >>
> >> I have trouble keeping all the places you can configure sizes
> >> straight, but one way to limit the number of active mdbs is to give
> >> the inbound resource adapter its own thread pool and limit that
> >> size.  I think there's a more direct way but don't recall what it is.
> >>
> >> If the number of outbound connections is at least the number of mdbs
> >> I would expect you wouldn't run into problems.
> >>
> >> Maybe someone with more actual experience can give some more informed
> >> advice.
> >>
> >> thanks
> >> david jencks
> >>
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >
> > --
> > View this message in context: http://www.nabble.com/Sharing-
> > resources-in-an-MDB-tf3412013s134.html#a10182882
> > Sent from the Apache Geronimo - Users mailing list archive at
> > Nabble.com.
> >
>

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