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https://issues.apache.org/jira/browse/LUCENE-1703?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12721954#action_12721954
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Tim Smith commented on LUCENE-1703:
-----------------------------------
My primary use case for this is to stabilize an index prior to performing a
backup operation
If background merges are ongoing, then partial segment files will be written to
disk (potentially while an rsync or other operation is running)
this will result in partial segments being backed up
while this should still be a viable index, as the partial segments have not
been "committed", it results in an unclean backup (this can result in rsync
throwing warnings/errors (which operations people greatly dislike)
> Add a waitForMerges() method to IndexWriter
> -------------------------------------------
>
> Key: LUCENE-1703
> URL: https://issues.apache.org/jira/browse/LUCENE-1703
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Affects Versions: 2.4
> Reporter: Tim Smith
> Attachments: IndexWriter.java.diff
>
>
> It would be very useful to have a waitForMerges() method on the IndexWriter.
> Right now, the only way i can see to achieve this is to call
> IndexWriter.close()
> ideally, there would be a method on the IndexWriter to wait for merges
> without actually closing the index.
> This would make it so that background merges (or optimize) can be waited for
> without closing the IndexWriter, and then reopening a new IndexWriter
> the close() reopen IndexWriter method can be problematic if the close() fails
> as the write lock won't be released
> this could then result in the following sequence:
> * close() - fails
> * force unlock the write lock (per close() documentation)
> * new IndexWriter() (acquires write lock)
> * finalize() on old IndexWriter releases the write lock
> * Index is now not locked, and another IndexWriter pointing to the same
> directory could be opened
> If you don't force unlock the write lock, opening a new IndexWriter will fail
> until garbage collection calls finalize() the old IndexWriter
> If the waitForMerges() method is available, i would likely never need to
> close() the IndexWriter until right before the process being shutdown, so
> this issue would not occur (worst case scenario, the waitForMerges() fails)
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