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https://issues.apache.org/jira/browse/ARTEMIS-3075?focusedWorklogId=547068&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-547068
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ASF GitHub Bot logged work on ARTEMIS-3075:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 03/Feb/21 15:27
Start Date: 03/Feb/21 15:27
Worklog Time Spent: 10m
Work Description: jbertram commented on pull request #3428:
URL: https://github.com/apache/activemq-artemis/pull/3428#issuecomment-772593216
One of the benefits of scale-down as opposed to normal fail-over is that
non-persistent messages are preserved. In normal fail-over only persistent
messages are preserved.
It is, of course, normal for temporary queues to disappear when a client
disconnects, but it also might be nice for scale-down to preserve these
temporary queues so clients can reconnect and continue their work since the
client itself was not responsible for the disconnect. For normal clients using
temporary queues who get disconnect because some kind of spurious network issue
they are able to reconnect back to their temporary queue unless the connection
ttl has elapsed and the broker has cleaned up the queue. This is discussed in
[the
documentation](http://activemq.apache.org/components/artemis/documentation/latest/client-reconnection.html).
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Issue Time Tracking
-------------------
Worklog Id: (was: 547068)
Time Spent: 1h 10m (was: 1h)
> Scale down of activemq.notifications causes issues
> --------------------------------------------------
>
> Key: ARTEMIS-3075
> URL: https://issues.apache.org/jira/browse/ARTEMIS-3075
> Project: ActiveMQ Artemis
> Issue Type: Bug
> Affects Versions: 2.16.0
> Reporter: Jens De Temmerman
> Assignee: Domenico Francesco Bruscino
> Priority: Major
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> Situation: a 2 server cluster, live-live, configured statically. Servers are
> configured to scale-down to each other when shut down.
> When the servers are live, they create a queue on each other's
> "activemq.notifications" address. This is done in ClusterConnectionBridge, I
> assume this is needed to get clustering to work properly.
> The queues are named
> "notif.6dca3cd4-5a61-11eb-8600-005056a1a158.ActiveMQServerImpl_serverUUID=903148b3-4455-11eb-bfed-005056a1a158"
> with serverUUID on server B pointing to server A and vice versa. (the UUID
> after "notif." is random).
> However, when server A is shut down, in some cases messages remain on this
> queue. This may be a timing issue, but regardless, when scaling down starts
> the ScaleDownHandler finds messages:
>
> {code:java}
> 2021-01-19 15:32:42,780 DEBUG
> [org.apache.activemq.artemis.core.server.impl.ScaleDownHandler] Scaling down
> address activemq.notifications
> 2021-01-19 15:32:42,781 DEBUG
> [org.apache.activemq.artemis.core.server.impl.ScaleDownHandler] Scaling down
> messages on address activemq.notifications
> 2021-01-19 15:32:42,781 DEBUG
> [org.apache.activemq.artemis.core.server.impl.ScaleDownHandler] Scaling down
> messages on address activemq.notifications / performing loop on queue
> QueueImpl[name=notif.6dca3cd4-5a61-11eb-8600-005056a1a158.ActiveMQServerImpl_serverUUID=903148b3-4455-11eb-bfed-005056a1a158,
> postOffice=PostOfficeImpl
> [server=ActiveMQServerImpl::serverUUID=bbd13595-4473-11eb-aadd-005056a1b044],
> temp=true]@64be4624
> 2021-01-19 15:32:42,786 DEBUG
> [org.apache.activemq.artemis.core.server.impl.ScaleDownHandler] Reading
> message CoreMessage[messageID=796047343,durable=true,userID=null,priority=0,
> timestamp=Tue Jan 19 15:32:42 CET 2021,expiration=0, durable=true,
> address=activemq.notifications,size=1000,properties=TypedProperties[_AMQ_Distance=0,_AMQ_ConsumerCount=0,_AMQ_User=REDACTED,_AMQ_ROUTING_TYPE=0,_AMQ_SessionName=7b37ba58-5a5d-11eb-b854-005056bd7345,_AMQ_Address=REDACTED,_AMQ_RemoteAddress=/REDACTED:42310,_AMQ_NotifTimestamp=1611066762756,_AMQ_ClusterName=2f88994d-5d37-4976-afcd-b879fb80993abbd13595-4473-11eb-aadd-005056a1b044,_AMQ_RoutingName=2f88994d-5d37-4976-afcd-b879fb80993a,_AMQ_NotifType=CONSUMER_CLOSED,_AMQ_FilterString=NULL-value]]@187982968
> from queue
> QueueImpl[name=notif.6dca3cd4-5a61-11eb-8600-005056a1a158.ActiveMQServerImpl_serverUUID=903148b3-4455-11eb-bfed-005056a1a158,
> postOffice=PostOfficeImpl
> [server=ActiveMQServerImpl::serverUUID=bbd13595-4473-11eb-aadd-005056a1b044],
> temp=true]@64be4624
> {code}
> Of course, this queue doesn't exist on node B. But this causes this queue to
> be created on node B:
> {code}
> 2021-01-19 15:32:42,814 DEBUG
> [org.apache.activemq.artemis.core.server.impl.ScaleDownHandler] Failed to get
> queue ID, creating queue [addressName=activemq.notifications,
> queueName=notif.6dca3cd4-5a61-11eb-8600-005056a1a158.ActiveMQServerImpl_serverUUID=903148b3-4455-11eb-bfed-005056a1a158,
> routingType=MULTICAST, filter=_AMQ_Binding_Type<>2 AND _AMQ_NotifType IN
> ('SESSION_CREATED','BINDING_ADDED','BINDING_REMOVED','CONSUMER_CREATED','CONSUMER_CLOSED','PROPOSAL','PROPOSAL_RESPONSE','UNPROPOSAL')
> AND _AMQ_Distance<1 AND (((_AMQ_Address NOT LIKE 'activemq%') AND
> (_AMQ_Address NOT LIKE '$.artemis.internal.sf.%') AND (_AMQ_Address NOT LIKE
> 'activemq.management%'))) AND (_AMQ_NotifType = 'SESSION_CREATED' OR
> (_AMQ_Address NOT LIKE 'activemq.notifications%')), durable=false]
> {code}
> But on node B, there will never be any consumers on this queue. Since
> activemq.notifications is multicast, all messages sent to it are distributed
> to this queue as well, but never consumed nor purged (unless done manually).
> I'm not sure what the correct course of action is, but somehow this queue
> should not be considered for scale-down, as it creates a situation that
> requires manual intervention to fix.
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