Matthias J. Sax created KAFKA-20879:
---------------------------------------
Summary: Consider to add a `SuspendReason` to
`StateRestoreListener#onRestoreSupsended
Key: KAFKA-20879
URL: https://issues.apache.org/jira/browse/KAFKA-20879
Project: Kafka
Issue Type: Improvement
Components: streams
Reporter: Matthias J. Sax
## Description
When an active task's restoration is interrupted,
`StateRestoreListener.onRestoreSuspended` is called, but it does not say why.
There are three reasons it can happen, and they are indistinguishable to the
application:
- the task was assigned to another instance,
- the task was demoted to a standby task on this instance,
- this instance is shutting down.
The sibling callback on the other listener does distinguish them.
`StandbyUpdateListener.onUpdateSuspended` receives a `SuspendReason`. An
application that follows both listeners to track where its tasks live therefore
gets a cause for a replica that stops updating, but none for an active task
that stops restoring.
### Scope: only a task that is still restoring
This is limited to an active task that had **not** finished restoring. If a
task is RUNNING and there is no restoration in progress, there is nothing for a
restore listener to report, and the resulting standby task is reported through
`StandbyUpdateListener.onUpdateStart` as usual. So overall it's a rare case,
but still worth to address.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
