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https://issues.apache.org/jira/browse/JAMES-4064?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17877285#comment-17877285
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Benoit Tellier commented on JAMES-4064:
---------------------------------------
+1
We had similar issues on the Rabbit implementation where we wanted to create 1
queue per James server.
It turns out the management of the cleanup of that per-james server queue (and
cleanup after reboot!) was a surprisingly annoying task.
- built in auto-delete queues are prone to being destroyed too early upon
network failures
- we ended up relying on queue TTL wich was more resiliant
- a cleanup upon the shutdown process (@Predestroy) helped mitigating a bit
also the issue - at least clean shutdowns do not leak!
I do not know how this past experience converts to the Pulsar context and hope
the pulsar handling will be more straight forward.
> Mailqueue filters should not use durable subscriptions
> ------------------------------------------------------
>
> Key: JAMES-4064
> URL: https://issues.apache.org/jira/browse/JAMES-4064
> Project: James Server
> Issue Type: Sub-task
> Components: pulsar, Queue
> Reporter: Jean Helou
> Priority: Major
>
> Removal in a distributed system requires a way to distribute the filters to
> the various instances of the mailqueue. This was implemented by pushing
> filters in a dedicated pulsar topic.
>
> Since each instance needs to read the topic from the start to compile all the
> filters, it is necessary to have unique names for an exclusive subscription
> (see
> [https://pulsar.apache.org/docs/3.3.x/concepts-messaging/#subscriptions)]
> If the instances used a shared subscription they would not receive filters
> that have already been received by other members of the subscription.
>
> The current implementation uses Durable subscriptions and the uniqueness of
> the name is generated by adding an UUID. Unfortunately this means that a
> server restart will create a new subscription and the previous one will
> remain forever.
>
> I recently discovered that pulsar has a limit on the total number of durable
> subscriptions :D eventually preventing the creation of new ones.
>
> The filters should be migrated to non durable subscriptions (see
> [https://pulsar.apache.org/docs/3.3.x/concepts-messaging/#subscription-modes)]
>
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