[jira] [Created] (OAK-8513) Concurrent access via CopyOnRead directory can lead to reading directly off of remote

["Vikas Saurabh (JIRA)" <ji...@apache.org>]

Vikas Saurabh created OAK-8513:
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             Summary: Concurrent access via CopyOnRead directory can lead to reading directly off of remote
                 Key: OAK-8513
                 URL: https://issues.apache.org/jira/browse/OAK-8513
             Project: Jackrabbit Oak
          Issue Type: Improvement
          Components: lucene
            Reporter: Vikas Saurabh
            Assignee: Vikas Saurabh


Even with prefetch enabled having 2 CopyOnRead directories pointing to same index can lead to one of the instance reading index files directly off of remote index.

The reason this happens is because {{COR#copyFilesToLocal}} explicitly chooses to work with remote if index copier reports that a copy is in progress.

This wasn't a problem earlier when COR was only used via IndexTracker so concurrent COR instances weren't expected (COR's avoid local for conc copy was probably worried about non-prefetch case).

But with OAK-8097, {{DefaultDirectoryFactory}} also uses COR to bring the files. Which means that if there's a query against an index which is getting updated as well then either of COR instance could read directly from remote.
The condition should only be relevant during early app start up but since this can happen in default configuration, we should attempt to fix this.



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