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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