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https://issues.apache.org/jira/browse/LUCENE-3373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17540795#comment-17540795
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Thomas Hoffmann commented on LUCENE-3373:
-----------------------------------------
The stalling depends on maxMergeCount, as far as I can see.
Maybe it should be worth logging a warning (instead of verbose). Thus it would
be more visible if it happens again.
An unbounded wait should be avoided for sure. Some logic about a maximum wait
time could help (as a workaround to avoid an infinite wait). This event should
be logged to catch the real reason and find the root cause.
> waitForMerges deadlocks if background merge fails
> -------------------------------------------------
>
> Key: LUCENE-3373
> URL: https://issues.apache.org/jira/browse/LUCENE-3373
> Project: Lucene - Core
> Issue Type: Bug
> Components: core/index
> Affects Versions: 3.0.3
> Reporter: Tim Smith
> Priority: Major
>
> waitForMerges can deadlock if a merge fails for ConcurrentMergeScheduler
> this is because the merge thread will die, but pending merges are still
> available
> normally, the merge thread will pick up the next merge once it finishes the
> previous merge, but in the event of a merge exception, the pending work is
> not resumed, but waitForMerges won't complete until all pending work is
> complete
> i worked around this by overriding doMerge() like so:
> {code}
> protected final void doMerge(MergePolicy.OneMerge merge) throws IOException
> {
> try {
> super.doMerge(merge);
> } catch (Throwable exc) {
> // Just logging the exception and not rethrowing
> // insert logging code here
> }
> }
> {code}
> Here's the rough steps i used to reproduce this issue:
> override doMerge like so
> {code}
> protected final void doMerge(MergePolicy.OneMerge merge) throws IOException
> {
> try {Thread.sleep(500L);} catch (InterruptedException e) { }
> super.doMerge(merge);
> throw new IOException("fail");
> }
> {code}
> then, if you do the following:
> loop 50 times:
> addDocument // any doc
> commit
> waitForMerges // This will deadlock sometimes
> SOLR-2017 may be related to this (stack trace for deadlock looked related)
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