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Posted to dev@phoenix.apache.org by "Chinmay Kulkarni (Jira)" <ji...@apache.org> on 2020/10/28 00:16:00 UTC
[jira] [Updated] (PHOENIX-5945) TaskRegionObserver can kick off the
same task multiple times if SYSTEM.TASK has split
[ https://issues.apache.org/jira/browse/PHOENIX-5945?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Chinmay Kulkarni updated PHOENIX-5945:
--------------------------------------
Fix Version/s: (was: 4.16.0)
4.17.0
4.16.1
> TaskRegionObserver can kick off the same task multiple times if SYSTEM.TASK has split
> -------------------------------------------------------------------------------------
>
> Key: PHOENIX-5945
> URL: https://issues.apache.org/jira/browse/PHOENIX-5945
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.15.0
> Reporter: Chinmay Kulkarni
> Priority: Major
> Fix For: 5.1.0, 4.16.1, 4.17.0
>
>
> We don't specify a split policy for [SYSTEM.TASK|https://github.com/apache/phoenix/blob/5f9364db7e4925229704706e148e62f4cf4ec4c2/phoenix-core/src/main/java/org/apache/phoenix/query/QueryConstants.java#L381], so by default it will be allowed to split. Now if SYSTEM.TASK spans multiple regions, each region's [postOpen|https://github.com/apache/phoenix/blob/5f9364db7e4925229704706e148e62f4cf4ec4c2/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/TaskRegionObserver.java#L137] schedules the SelfHealingTask at the specified interval and so [each region will run a FTS on the table|https://github.com/apache/phoenix/blob/5f9364db7e4925229704706e148e62f4cf4ec4c2/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/TaskRegionObserver.java#L159] and try to kick-off all the incomplete and non-failed tasks.
> This can lead to the same tasks being kicked off multiple times as a corner race condition in spite of [this check|https://github.com/apache/phoenix/blob/5f9364db7e4925229704706e148e62f4cf4ec4c2/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/TaskRegionObserver.java#L187-L195] (which is another FTS) and also lead to unnecessary extra load on the server.
> We do not explicitly outline that tasks need to be idempotent, so we should handle this properly in the TaskRegionObserver so that each region is only responsible for tasks lying within its boundaries.
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