Re: is ISession thread safe?

[Jim Gomes <e....@gmail.com>]

It looks like you have entered JIRA AMQNET-136 (
https://issues.apache.org/activemq/browse/AMQNET-136) for this problem.
Thanks!

- Jim

On Wed, Jan 21, 2009 at 11:30 AM, sbs1982 <sa...@sac.com> wrote:

>
> ++++++++++++++++++++++++++++++++++++++++++++++
>
> MSDN talking about lock(this)
>
> http://msdn.microsoft.com/en-us/library/c5kehkcz(VS.80).aspx<http://msdn.microsoft.com/en-us/library/c5kehkcz%28VS.80%29.aspx>
> lock (this) is a problem if the instance can be accessed publicly.
>
> I see lock(this) used heavily in MessageConsumer class....
> the consumer will be accessible to the main app as well.
>
> DEADLOCK SCENARIO:
>
> the deadlock occurs on close method of IMessageConsumer.
>
> Here is the scenario...
> Lets say we have the class below. The producer is calling the
> MessgeConsumers callback method.
> In this case its onMessage() method. Now lets assume there are 30K messages
> to be received in the call back. When we are on the 10th message and the
> user closes the trace Window the CloseWindow() method is called and the
> application stalls at the message consumers close method.
> Hope I am clear enough.
>
> Class TraceWindow
> {
> private IMessageConsumer consumerTrace = null;
> TraceWindow(Apache.NMS.IMessageConsumer iMessageConsumer)
> {
>            this.consumerTrace = iMessageConsumer;
>            if (consumerTrace != null)
>            {
>                this.consumerTrace.Listener += new
> MessageListener(OnMessage);
>            }
> }
>
>  public void OnMessage(Apache.NMS.IMessage bMsg)
> {
>        //inserts in WPF ObservableCollection
>            handleMessageDelegate Updater = new
> handleMessageDelegate(handleMessage);
>
>
> this.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Input,
>                     Updater, obj);
> }
>
> public void handleMessage(Object item)
>        {
>            lock (collectionTrace)
>            {
>                {
>                    collectionTrace.Add(item);
>
> LogManager.GetLogger("AlgoSystemCommunicatorLogger").Info(item);
>                }
>            }
>        }
>
>
> public void CloseWindow()
> {
>   consumerTrace.Close();   //////////////////////SYSTEM STALLS ON THIS CALL
> }
>
> }//end of class
>
>
>
> +++++++++++++++++++++++++++++++++++++++++++++++
>
>
> Timothy Bish wrote:
> >
> > On Wed, 2009-01-21 at 10:26 -0800, sbs1982 wrote:
> >> If one thread in my app is trying to create a temporary topic and I
> >> already
> >> have a few consumers(listening on other temp topics & processesing
> >> incoming
> >> messages on their respective call back methods i.e listeners) open. Now
> >> trying to call the close method of one of these consumers causes my app
> >> to
> >> go into deadlock.
> >
> > Can you create a test case that might reproduce the problem?  If you run
> > in the debugger can you pinpoint where the deadlock is occurring?
> >
> >> is there some know issue of close method of consumers locking?
> >>
> >> I looked at the code in the MessageConsumer..the first statement is
> >> lock(this).
> >> Some articles are out there saying that locking on this is unsafe?
> >
> > Can you provide references, I'd like to read up on this (no pun
> > intended).
> >
> > You may want to create a Jira issue to cover this problem.
> >
> > Regards
> > Tim.
> >
> >
> > --
> > Tim Bish
> > http://fusesource.com
> > http://timbish.blogspot.com/
> >
> >
> >
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/is-ISession-thread-safe--tp21589189p21590482.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>
>