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https://issues.apache.org/jira/browse/AMQ-9107?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Christopher L. Shannon reopened AMQ-9107:
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This doesn't have nearly enough testing around durable subscriptions and this
causes a memory leak. ConsumerInfo is not great to use as the key because that
object will change every time a consumer goes offline/online for a durable
subscription. I just ran a test where I went online/offline several times in a
row for a durable and the new map kept growing because the consumer id changed
each time.
The performance improvement would be nice but I'm skeptical about using
ConsumerInfo as a key here unless a lot more testing is done to prove no memory
leaks and things actually work for all edge cases including broker restarts,
etc.
Also, by introducing a second map you now have created race conditions because
the maps may get out of sync with some weird bug.
> Closing many consumers causes CPU to spike to 100%
> --------------------------------------------------
>
> Key: AMQ-9107
> URL: https://issues.apache.org/jira/browse/AMQ-9107
> Project: ActiveMQ
> Issue Type: Bug
> Affects Versions: 5.17.1, 5.16.5
> Reporter: Lucas Tétreault
> Assignee: Jean-Baptiste Onofré
> Priority: Major
> Fix For: 5.18.0, 5.16.6, 5.17.3
>
> Attachments: example.zip, image-2022-10-07-00-12-39-657.png,
> image-2022-10-07-00-17-30-657.png
>
> Time Spent: 2.5h
> Remaining Estimate: 0h
>
> When there are many consumers (~188k) on a queue, closing them is incredibly
> expensive and causes the CPU to spike to 100% while the consumers are closed.
> Tested on an Amazon MQ mq.m5.large instance (2 vcpu, 8gb memory).
> I have attached a minimal recreation of the issue where the following
> happens:
> 1/ Open 100 connections.
> 2/ Create consumers as fast as we can on all of those connections until we
> hit at least 188k consumers.
> 3/ Sleep for 5 minutes so we can observe the CPU come back down after opening
> all those connections.
> 4/ Start closing consumers as fast as we can.
> 5/ After all consumers are closed, sleep for 5 minutes to observe the CPU
> come back down after closing all the connections.
>
> In this example it seems 5 minutes wasn't actually sufficient time for the
> CPU to come back down and the consumer and connection counts seem to hit 0 at
> the same time:
> !image-2022-10-07-00-12-39-657.png|width=757,height=353!
>
> In a previous test with more time sleeping after closing all the consumers we
> can see the CPU come back down before we close the connections.
> !image-2022-10-07-00-17-30-657.png|width=764,height=348!
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