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https://issues.apache.org/jira/browse/JCR-5142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17950113#comment-17950113
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Tom Duffey commented on JCR-5142:
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I'm looking ahead to the other piece of this which is the need to similarly
pause/resume the MultiIndex from changing anything on disk.
It seems this includes at least the following operations.
# Committing the volatile index to the persistent index. Looks like this can
be triggered by either an update action or the `flush()` method which is a
scheduled task and also the recovery process. In any case seems like a lock
would be needed around the `flush()` method and also the
`checkVolatileCommit()` method.
# The index merging process implemented in `IndexMerger`. This thing seems to
already have a lock so perhaps it could be exposed or pause/resume methods
added.
I hate to touch this code due to the complexities around multi-threading and
potential deadlocks. Not to mention this is my first time diving into the
depths of Jackrabbit. But it does seem necessary to ensure a consistent index
backup, no?
> Improve index hot backup
> ------------------------
>
> Key: JCR-5142
> URL: https://issues.apache.org/jira/browse/JCR-5142
> Project: Jackrabbit Content Repository
> Issue Type: Improvement
> Components: clustering, indexing
> Affects Versions: 2.23.1
> Reporter: Tom Duffey
> Priority: Minor
>
> As a user with high performance and resiliency needs Jackrabbit should
> provide a way to do a hot backup of the Lucene index to avoid having to take
> a node offline.
> As a step in that direction ClusterNode should provide a way to pause and
> resume synchronization. This way we can pause updates on a node, backup the
> index and then resume.
> Note this ticket only proposes handling the JCR cluster sync operation but
> the node itself could also be updating its index. Perhaps a second ticket
> could be made to also pause merging the volatile indexes back to the
> persistent indexes?
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