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From Elliot Barlas <elliotbar...@gmail.com>
Subject Re: Why do persistent messages exhaust memory and lock out consumers?
Date Thu, 11 Jun 2009 16:27:10 GMT

AMQ version 5.2.0


rajdavies wrote:
> 
> which version are you using ?
> On 11 Jun 2009, at 01:48, Elliot Barlas wrote:
> 
>>
>> Scenario:
>> -Minimal AMQ message broker with persistence enabled and default usage
>> values of 64 MB memory limit, 10 GB temp store limit, and 100 GB  
>> persistent
>> store limit
>> -AMQ producer client sending 100 KB persistent messages to queue X  
>> in a loop
>> with a short sleep (roughly 10 msgs/second)
>>
>> Observations:
>> -MemoryPercentUsage reaches 70% after a few minutes and remains there
>> -StorePercentUsage remains at 0 (since persistent store limit is so  
>> high)
>> -Disk usage under persistent data directory increases as expected
>>
>>
>> Why is the memory percent usage increasing so rapidly?  Shouldn't  
>> messages
>> go directly to the persistent store?  If memory is used, shouldn't  
>> it be
>> flushed once it reaches a certain threshold?
>>
>>
>> Scenario continued:
>> -A second AMQ producer client sending 100 KB persistent messages to  
>> queue Y
>> in a loop
>> -AMQ consumer client consuming messages from queue Y in a loop
>>
>> Observations continued:
>> -MemoryPercentUsage remains at 70%
>> -StorePercentUsage remains at 0
>> -Disk usage under persistent data directory continues to increase
>> -NO messages dequeued from queue Y!
>>
>>
>> Shockingly, messages are NOT consumed from queue Y in the scenario  
>> described
>> above.  Once the 70% memory usage threshold is reached, messages  
>> cannot be
>> consumed from queue Y.  After further testing, I have seen the  
>> messages can
>> be consumed from queue X, which decreased the memory percent used, and
>> restores the system (messages can then be consumed from other queues).
>>
>> Why is this happening?  Has anyone else seen this?
>>
>> The same test with non-persistent messages is not problematic.  The  
>> memory
>> percent usage increases, but once it reaches 70% the messages are  
>> flushed to
>> the temp store and the percent usage is reduce to 0%
>>
>> Thanks,
>> Elliot
>> -- 
>> View this message in context:
>> http://www.nabble.com/Why-do-persistent-messages-exhaust-memory-and-lock-out-consumers--tp23973571p23973571.html
>> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>>
> 
> 
> 

-- 
View this message in context: http://www.nabble.com/Why-do-persistent-messages-exhaust-memory-and-lock-out-consumers--tp23973571p23984660.html
Sent from the ActiveMQ - User mailing list archive at Nabble.com.


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