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https://issues.apache.org/activemq/browse/AMQ-2400?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dejan Bosanac reassigned AMQ-2400:
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Assignee: Dejan Bosanac
> Default settings lead to paging and high latency for non persistent pub/sub
> ---------------------------------------------------------------------------
>
> Key: AMQ-2400
> URL: https://issues.apache.org/activemq/browse/AMQ-2400
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.3.0
> Environment: N/A
> Reporter: Colin MacNaughton
> Assignee: Dejan Bosanac
>
> The current default config doesn't enable a memoryLimit or flow control for
> topics which consequently leads to high latency and lower throughput.
> I ended up tweaking the default config to limit destination sizes and enable
> flow control as follows:
> <destinationPolicy>
> <policyMap>
> <policyEntries>
> <policyEntry topic=">" producerFlowControl="true" memoryLimit="1mb">
>
> <pendingSubscriberPolicy>
> <vmCursor/>
> </pendingSubscriberPolicy>
> </policyEntry>
> <policyEntry queue=">" producerFlowControl="true" memoryLimit="1mb"/>
> </policyEntries>
> </policyMap>
> </destinationPolicy>
> The current default config was resulting in really high latencies in non
> persistent pub sub tests (> 2 minutes!). With the new settings throughput
> doubled and average latency dropped to 3 seconds.
> However, it seems like there is some resistance to enabling flow control by
> default: http://issues.apache.org/activemq/browse/AMQ-2318, as naïve users
> might erroneously interpret this as a hang.
> A possible compromise appropriate for the 5.3.0 release time frame would be
> to log a warning the first time flow control is triggered for a destination,
> to assist naive users in troubleshooting producer pauses.
> More long term, it might be worth introucing a more sophisticated mechanism
> for when we page to disk like only do so when there are no consumers
> connected. A policy similar to this is already being pursued in the amq 6.0
> prototype.
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