After a node is scaled down to a target node, the sf queue in the
target node is not deleted.
Normally this is fine because may be reused when the scaled down
node is back up.
However in cloud environment many drainer pods can be created and
then shutdown in order to drain the messages to a live node (pod).
Each drainer pod will have a different node-id. Over time the sf
queues in the target broker node grows and those sf queues are
no longer reused.
Although use can use management API/console to manually delete
them, it would be nice to have an option to automatically delete
those sf queue/address resources after scale down.
In this PR it added a boolean configuration parameter called
cleanup-sf-queue to scale down policy so that if the parameter
is "true" the broker will send a message to the
target broker signalling that the SF queue is no longer
needed and should be deleted.
If the parameter is not defined (default) or is "false"
the scale down won't remove the sf queue.
- Split protocols into individual chapters
- Reorganize summary to flow more logically
- Fill in missing parameters in configuration index
- Normalize spaces for ordered and unordered lists
- Re-wrap lots of text for readability
- Fix incorrect XML snippets
- Normalize table formatting
- Improve internal links with anchors
- Update content to reflect new address model
- Resized architecture images to avoid excessive white-space
- Update some JavaDoc
- Update some schema elements
- Disambiguate AIO & ASYNCIO where necessary
- Use URIs instead of Objects in code examples
Added a wait-for-activation option to shared-store master HA policies.
This option is enabled by default to ensure unchanged server startup behavior.
If this option is enabled, ActiveMQServer.start() with a shared-store master server will not return
before the server has been activated.
If this options is disabled, start() will return after a background activation thread has been started.
The caller can use waitForActivation() to wait until server is activated, or just check the current activation status.
The failback process needs to be deterministic rather than relying on various
incarnations of Thread.sleep() at crucial points. Important aspects of this
change include:
1) Make the initial replication synchronization process block at the very
last step and wait for a response from the replica to ensure the replica has
as the necessary data. This is a critical piece of knowledge during the
failback process because it allows the soon-to-become-backup server to know
for sure when it can shut itself down and allow the soon-to-become-live
server to take over. Also, introduce a new configuration element called
"initial-replication-sync-timeout" to conrol how long this blocking will occur.
2) Set the state of the server as 'LIVE' only after the server is fully
started. This is necessary because once the soon-to-be-backup server shuts
down it needs to know that the soon-to-be-live server has started fully before
it restarts itself as the new backup. If the soon-to-be-backup server restarts
before the soon-to-be-live is fully started then it won't actually become a
backup server but instead will become a live server which will break the
failback process.
3) Wait to receive the announcement of a backup server before failing-back.
Urs Roesch
Justin Bertram
Clebert Suconic
Howard Gao
Sebastian Lövdahl
art-licis
Ville Skyttä
Stanislav Knot
Bernd Gutjahr
Andy Taylor
Pat Fox
Martyn Taylor
Andy Taylor
Justin Bertram