[jira] [Commented] (KYLIN-1883) Consensus Problem when running the tool, MetadataCleanupJob

["Shaofeng SHI (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KYLIN-1883?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15451221#comment-15451221 ] 

Shaofeng SHI commented on KYLIN-1883:
-------------------------------------

what's the fixed version? could you please properly set such field when ever fix an issue? Otherwise user won't know which version has the fix, and it will be missed from the release notes. thanks.

> Consensus Problem when running the tool, MetadataCleanupJob
> -----------------------------------------------------------
>
>                 Key: KYLIN-1883
>                 URL: https://issues.apache.org/jira/browse/KYLIN-1883
>             Project: Kylin
>          Issue Type: Bug
>            Reporter: Zhong Yanghong
>            Assignee: Zhong Yanghong
>         Attachments: better_solution_for_consensus_issue_of_MetadataCleanupJob.patch
>
>
> When do the cleanup, current strategy is as follows:
> 1. firstly create an referenceSet
> 2. then add items not belonging to the referenceSet to the toDeleteSet
> 3. finally delete those items in the toDeleteSet
> Consensus issue will occur since we cannot make sure that all of the items in toDeleteSet are not referenced in case that referenceSet changes during the process.
> For example, before the cleanup, SEGMENT_A is deleted and leave a DICT_A created at the building step. Then the referenceSet will not include DICT_A. After creating the reference set, SEGMENT_B is starting to build. Since DICT_A still exists, it can still be referenced by SEGMENT_B. Then DICT_A will still be included in the toDeleteSet and will be deleted later. Finally SEGMENT_B only owns a reference with no data.



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