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From "Yannick (JIRA)" <j...@apache.org>
Subject [jira] Created: (AMQ-2159) One evicted message out of two is delivered to the consumer
Date Thu, 12 Mar 2009 14:39:39 GMT
One evicted message out of two is delivered to the consumer
-----------------------------------------------------------

                 Key: AMQ-2159
                 URL: https://issues.apache.org/activemq/browse/AMQ-2159
             Project: ActiveMQ
          Issue Type: Bug
          Components: Broker
    Affects Versions: 5.2.0
         Environment: Windows Xp, Java 5, ActiveMQ 5.2
            Reporter: Yannick


A problem in message eviction seems to cause a strange behavior of message delivery. After
a slow consumer consumed it's prefetched messages, it start receiving one message out of two
that were produced. When stepping into the sources I noticed that one message evicted out
of two is dispatched to the destination even if no message have been consumed during that
time. The problem seems to be in the class 'TopicSubscription'. This is what I found:

- When a message is discarded dequeueCounter is incremented. 
- Then next time a message arrives it is evicted then dispatchMatched is called. 
- Because dequeueCounter have been called without any message dispatched, isFull() return
false. 
- As a result it assumes there is an empty room in the prefetch and dispatch the message.


The following example show what I expect against what I get when I produce 100 messages with
a unique ID then consume 10 message and output the message ID. Prefetch size is 5.

Expected:
0, 1, 2, 3, 4, 95, 96, 97, 98, 99

What I really get
 0, 1, 2, 3, 4, 5, 7, 9, 11, 13

I made a test application and a unit test, I didn't found how to attach it to the issue.


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