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https://issues.apache.org/jira/browse/AMQ-4467?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15814885#comment-15814885
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Christopher L. Shannon commented on AMQ-4467:
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Good catch [~gtully]. A couple things...., First, if memory usage now properly
goes up to 100% usage across all destinations instead of stopping at the high
water mark (typically 70%) will that ever effect paging in for dispatch? I'm
pretty sure the pending cursors will still page in for dispatch and that the
memory usage is just used for producers and not consumers but want to see if
you could think of any scenarios where dispatch would stop.
Second, should Topics honor this value as well? I.e. on this line in Topic
https://github.com/apache/activemq/blob/activemq-5.14.3/activemq-broker/src/main/java/org/apache/activemq/broker/region/Topic.java#L376
memory usage is checked for full but should it honor the high water mark
instead?
> Memory usage percent can be exceeded much if PFC is disabled
> ------------------------------------------------------------
>
> Key: AMQ-4467
> URL: https://issues.apache.org/jira/browse/AMQ-4467
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.x
> Reporter: SuoNayi
> Assignee: Gary Tully
> Fix For: 5.15.0
>
> Attachments: AMQ-4467.patch
>
>
> If PFC is disabled, when the store cursor checks limits, it checks only the
> memory percentage of its own MemoryUsage and compares it to the high water
> mark. Otherwise if PFC is enabled, it checks whether the MemoryUsage is
> "full" but the "isFull" method also checks its parents.
> This issue arrises when you have memory limits set on queues higher than the
> overall system limit, as well as if you have multiple queues who's memory
> limits combined are higher than the overall system limit. These settings must
> be taken into account.
> The original form can be found at
> http://activemq.2283324.n4.nabble.com/What-can-be-reason-of-460-memory-usage-limit-td4665651.html
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