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| Message selectors and priorities |
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| sfari |
 Posted: Fri Dec 21, 2007 1:42 am Post subject: Message selectors and priorities |
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Centurion
Joined: 15 Apr 2003
Posts: 144
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Hi all,
We have a performance problem on an existing application. I am currently trying to find out what could be the reason.
This is the rough application design:
We have three different types of messages (type=A, type=B, type=C) on a queue. Three different Message Driven Beans are consuming them using message selectors. The application designer decided that messages of type=A have the biggest priority=5, B has 4, and C has 3.
The message driven beans are all running in the same application server. On the queue I can see that there is only one connection open for browse and 3 for each MDB for input.
It seems that if messages with priority=5 (type=A) are constantly arriving it does slow down the consumption of the lower priority messages.
Does somebody know how the selecting mechanism with this only one connection for all three different selectors is exactly working? Is my assumption possible or does it sound absurd? How does priority influence selectors?
Thanks for any help! |
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| jefflowrey |
| Posted: Fri Dec 21, 2007 3:29 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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A classic example of why you don't want to share queues...
You're likely using one single ListenerPort for the queue, assigned to all three MDBs. This ListenerPort can only get one message at a time, and start one MDB instance. If it spends it spends all it's time starting messages of Type A, then it can't start the MDBs for Type B or C.
Also, using selectors on anything other than MsgID or correlationID is going to be slow!
Much better to either use three queues, or one MDB that doesn't use a selector and calls three session beans based on message type (a dispatcher pattern).
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I am *not* the model of the modern major general. |
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| bower5932 |
| Posted: Fri Dec 21, 2007 4:53 am Post subject: |
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Jedi Knight
Joined: 27 Aug 2001
Posts: 3023
Location: Dallas, TX, USA
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