[
https://issues.apache.org/jira/browse/KAFKA-20710?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18089649#comment-18089649
]
Shekhar Prasad Rajak commented on KAFKA-20710:
----------------------------------------------
verified with unit test and drafting a PR.
> ShareCoordinatorService periodic jobs can duplicate after share feature
> disable/re-enable
> -----------------------------------------------------------------------------------------
>
> Key: KAFKA-20710
> URL: https://issues.apache.org/jira/browse/KAFKA-20710
> Project: Kafka
> Issue Type: Bug
> Components: core
> Affects Versions: 4.3.0
> Reporter: Shekhar Prasad Rajak
> Assignee: Shekhar Prasad Rajak
> Priority: Major
> Fix For: 4.3.2
>
>
> ShareCoordinatorService schedules self-recursing timer jobs.
> Disable/re-enable only flips shouldRunPeriodicJob; old queued or in-flight
> tasks can recurse after re-enable and create
> duplicate job chains.
>
> void setupRecordPruning() {
> timer.add(new TimerTask(...) {
> public void run() {
> ...
> CompletableFuture.allOf(...).whenComplete((res, exp) ->
> { ... setupRecordPruning(); // schedules
> next prune job }
> );
> }
> });
> }
>
> 1. setupRecordPruning() adds timer task A.
> 2. Timer fires task A.
> 3. Task A does prune work.
> 4. When prune work completes, task A calls setupRecordPruning() again.
> 5. That adds timer task B.
> 6. Task B later does the same.
> The bug risk is: if feature is disabled/re-enabled while task A is still
> queued or in-flight, re-enable schedules a new task chain, but old task A may
> also resume and schedule another chain. Then you can have duplicate periodic
> jobs running.
>
> So Expected behavior is one active prune chain and one active snapshot chain
> per service instance. Add a generation guard /epoch fencing; so stale timer
> tasks and stale async completions cannot reschedule.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
