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https://issues.apache.org/jira/browse/LUCENE-3373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17540702#comment-17540702
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Vigya Sharma commented on LUCENE-3373:
--------------------------------------
I'm curious why we need to {{break}}
[here|https://github.com/apache/lucene/blob/main/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java#L539-L541]
if we realize we don't want to stall. Why can't we just let the thread
continue with scheduling all the other merges. I also realized that we could
exit from that while loop without scheduling all pending merges, if the thread
ran into any exceptions. That is another way that could cause an endless wait.
> 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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