[jira] [Created] (AMQNET-521) LRUCache not working correctly, which can cause Memory Leak and Slowdown

["Markus Jung (JIRA)" <ji...@apache.org>]

Markus Jung created AMQNET-521:
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             Summary: LRUCache not working correctly, which can cause Memory Leak and Slowdown
                 Key: AMQNET-521
                 URL: https://issues.apache.org/jira/browse/AMQNET-521
             Project: ActiveMQ .Net
          Issue Type: Bug
          Components: ActiveMQ
    Affects Versions: 1.7.1
            Reporter: Markus Jung
            Assignee: Jim Gomes


Reason: Duplicates are not handled correctly. Which causes one of the internal lists (entries) to grow over time until handling the numberous items increases processing overhead and cause a slowdown.

Background: We are pulling a queue using n consumers with zero prefetch for maximum round robin. (Using Failover-Transport.)
Processing a message can take time from split a second to several hours. Prefetching a message would not be good. Nether-the-less this is a good way to do it, we discovered increasing memory usage and slowing down of our "workers".

After a worker processed a task a new call to consumer.Receive(timeout) causes to send a new MessagePull request, which is put into the messageCache using the same id.
(ProcessMessagePull in ConnectionStateTracker)
This causes the grow.
Reason: In LRUCache.this method, the call to entries.Remove uses value and not currentValue.




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