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https://issues.apache.org/jira/browse/OAK-9785?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Julian Sedding reassigned OAK-9785:
-----------------------------------
Assignee: Julian Sedding
> Tar SegmentStore can be corrupted during compaction
> ---------------------------------------------------
>
> Key: OAK-9785
> URL: https://issues.apache.org/jira/browse/OAK-9785
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: segment-tar
> Affects Versions: 1.42.0
> Reporter: Julian Sedding
> Assignee: Julian Sedding
> Priority: Major
> Attachments: error.log.2022-06-09
>
>
> There is a scenario where a segment store can become corrupted, leading to
> {{SegmentNotFoundExceptions}} with very "young" {{SegmentIds}}, i.e. in the
> 1-2 digit millisecond range. E.g. {{SegmentId age=2ms}}.
> The scenario I observed looks as follows:
> - a blob is "lost" from the external blob store (presumably due to incorrect
> cloning of the instance, most likely only happens with unfortunate timing)
> - a tail revision GC run is performed (not sure if it matters that this was
> a tail compaction)
> -- the missing blob is encountered during compaction
> -- an exception other than an {{IOException}} (IIRC it was a
> {{{}IllegalArgumentException{}}}) is thrown due to the missing blob
> -- revision GC fails WITHOUT properly being aborted, and thus the partially
> written revision of the compaction run is not removed
> - more data is written on the instance
> - a full revision GC run is performed
> -- a referenced segment is removed due to the incorrect/confused revision
> data
> - the {{SegmentNotFoundException}} is first observed either during the
> remainder of the compaction run or when the respective node is requested the
> next time, usually during a traversal
> The root cause is in
> [{{AbstractCompactionStrategy}}|https://github.com/apache/jackrabbit-oak/blob/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/file/AbstractCompactionStrategy.java#L233],
> where only {{IOExceptions}} are caught.
> In order to improve the robustness of the code, I think we need to catch all
> {{Throwables}}. Otherwise we cannot guarantee that compaction is correctly
> aborted.
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