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From Timothy Bish <tabish...@gmail.com>
Subject Re: Configuring limits for advisory topics
Date Thu, 09 May 2013 19:12:53 GMT
On 05/09/2013 02:59 PM, Paul Gale wrote:
>> If you subscribe, the advisory broker will replay advisories for
> destinations, consumers, etc that exist, but the messages aren't retained.
>
> Perhaps I'm getting hung up on the distinction between 'replay' and
> 'retain.'  If the broker 'will replay advisories for destinations,
> consumers that exist' what is it 'replaying' if not 'retained' advisory
> messages? It cannot replay something it does not possess. Confused.
The replay is based on state, each destination, consumer, producer etch 
that the broker knows about at the time the client connects a new 
advisory message is generated.  If no consumer is subscribed to the 
target advisory topic the messages is dropped. The word Topic is your 
key here, a topic doesn't retain anything when no consumers are present.


>
>
> Thanks,
> Paul
>
> On Thu, May 9, 2013 at 2:28 PM, Christian Posta
> <christian.posta@gmail.com>wrote:
>
>> Nope. messages aren't retained. If you subscribe, the advisory broker will
>> replay advisories for destinations, consumers, etc that exist, but the
>> messages aren't retained. If there are no consumers, the messages are
>> discarded.
>>
>>
>> On Thu, May 9, 2013 at 11:24 AM, Paul Gale <paul.n.gale@gmail.com> wrote:
>>
>>> There are no subscriptions to the advisory topics at present. Even with
>> no
>>> subscriptions it was my understanding that these messages would
>> accumulate
>>> in memory (or disk) unless consumed. It was this accumulation that I was
>>> hoping to control. I was under the impression that advisory topics were
>>> treated differently than regular topics, where messages are discarded
>>> unless someone has subscribed. Is that not true?
>>>
>>> I have turned on advisory support 'just in case' someone wants to examine
>>> said messages. If these advisory messages are being discarded then I
>> guess
>>> I have nothing to worry about. What is the actual case?
>>>
>>> Is there any point in specifying a memoryLimit either?
>>>
>>> Thanks,
>>> Paul
>>>
>>>
>>> On Thu, May 9, 2013 at 12:23 PM, Christian Posta
>>> <christian.posta@gmail.com>wrote:
>>>
>>>> May want to check the size of topic subscriptions... the enqueue
>> counter
>>>> for a topic will always increase as messages are passed to the topic...
>>> the
>>>> subs are what hold on to the messages and the pending message limit
>>> applies
>>>> to them.
>>>>
>>>>
>>>> On Thu, May 9, 2013 at 7:17 AM, Paul Gale <paul.n.gale@gmail.com>
>> wrote:
>>>>> Hi,
>>>>>
>>>>> I am trying to configure the use of my advisory topics. Ideally I
>> want
>>> to
>>>>> have them retain advisory messages by time, e.g., 3 days worth, where
>>> if
>>>>> not consumed within that time frame they are purged. This is to
>> prevent
>>>>> build up of advisory messages. However, I cannot see a way to specify
>>> the
>>>>> limit to be time based.
>>>>>
>>>>> As an experiment I tried the following config (with the limit
>>>> deliberately
>>>>> set very low):
>>>>>
>>>>>            <policyEntry topic="ActiveMQ.Advisory.>"
>>>>>                         memoryLimit="2mb"
>>>>>                         gcInactiveDestinations="false">
>>>>>              <pendingMessageLimitStrategy>
>>>>>                <constantPendingMessageLimitStrategy limit="10"/>
>>>>>              </pendingMessageLimitStrategy>
>>>>>            </policyEntry>
>>>>>
>>>>>
>>>>> It's not working. From looking at the web console it's clear that
>> some
>>>>> advisory topics go past the configured limit of 10 as the enqueued
>>> count
>>>>> keeps climbing.
>>>>>
>>>>> Is the memory limit taking precedence over the pending message limit
>>>>> strategy or is the enqueued count misleading and not reliable?
>>>>>
>>>>> If this is not the right way to approach this problem please advise
>> on
>>>> what
>>>>> would be the optimal configuration.
>>>>>
>>>>> FTW: the systemUsage is configured as follows:
>>>>>
>>>>>      <systemUsage>
>>>>>        <systemUsage>
>>>>>          <memoryUsage>
>>>>>            <memoryUsage limit="50m"/>
>>>>>          </memoryUsage>
>>>>>          <storeUsage>
>>>>>            <storeUsage limit="50m"/>
>>>>>          </storeUsage>
>>>>>          <tempUsage>
>>>>>            <tempUsage limit="50m"/>
>>>>>          </tempUsage>
>>>>>        </systemUsage>
>>>>>      </systemUsage>
>>>>>
>>>>> Thanks,
>>>>> Paul
>>>>>
>>>>
>>>>
>>>> --
>>>> *Christian Posta*
>>>> http://www.christianposta.com/blog
>>>> twitter: @christianposta
>>>>
>>
>>
>> --
>> *Christian Posta*
>> http://www.christianposta.com/blog
>> twitter: @christianposta
>>


-- 
Tim Bish
Sr Software Engineer | RedHat Inc.
tim.bish@redhat.com | www.fusesource.com | www.redhat.com
skype: tabish121 | twitter: @tabish121
blog: http://timbish.blogspot.com/


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