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From pdec...@yahoo.com
Subject Re: [Mira] Commented: (LUCENE-1555) Deadlock while optimize
Date Wed, 11 Mar 2009 13:37:52 GMT

-----Original Message-----
From: "Michael McCandless (JIRA)" <jira@apache.org>

Date: Wed, 11 Mar 2009 05:56:50 
To: <java-dev@lucene.apache.org>
Subject: [jira] Commented: (LUCENE-1555) Deadlock while optimize



    [ https://issues.apache.org/jira/browse/LUCENE-1555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12680864#action_12680864
] 

Michael McCandless commented on LUCENE-1555:
--------------------------------------------

bq. First of all, I could solve the problem by using IndexWriter.close(true) instead of IndexWriter.close().

Did you mean false instead of true?  (waitForMerges=true is what
close() does by default).

This (false) is dangerous to do, always, since it could result in merge
starvation whereby long-running merges never have a chance to
complete (I just updated 2.9 javadocs to state this).

{quote}
The indexer thread will index new data periodically. But if the indexer threat is started,
it will perform an optimize as well. So it could happen that

((ConcurrentMergeScheduler)indexWriter.getMergeScheduler()).sync();
indexWriter.close(true);

and

indexWriter = new IndexWriter(indexDirectory, analyser , false, MaxFieldLength.UNLIMITED);
indexWriter.optimize(MAX_MERGED_FILES);
((ConcurrentMergeScheduler)indexWriter.getMergeScheduler()).sync();
indexWriter.close(true);

will be executed one after another. With close() this could result in a lock.
{quote}

I don't really follow what you're saying here.  Are you saying calling
ConcurrentMergeScheduler.sync() leads to the deadlock, or, prevents
it?

By indexer thread, do you mean you are launching your own threads to
do indexing, or are you talking about ConcurrentMergeScheduler's
threads?

Are you doing any external synchronization on IndexWriter yourself?

Are you calling IndexWriter.close() from multiple threads?

Can you post every thread in your thread dump?  (Or, is it really the
case that you only have 2 threads?).

bq. I've only changed the maxFieldLength of the writer to 50000.

OK that's fine.


> Deadlock while optimize
> -----------------------
>
>                 Key: LUCENE-1555
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1555
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Index
>    Affects Versions: 2.4
>         Environment: ubuntu 8.04, java 1.6 update 07, Lucene 2.4.0
>            Reporter: Stefan Heidrich
>            Assignee: Michael McCandless
>
> Sometimes after starting the thread with the indexer, the thread will hang in the following
threads.
> Thread [Lucene Merge Thread #0] (Ausgesetzt)	
> 	IndexWriter.commitMerge(MergePolicy$OneMerge, SegmentMerger, int) Line: 3751	
> 	IndexWriter.mergeMiddle(MergePolicy$OneMerge) Line: 4240	
> 	IndexWriter.merge(MergePolicy$OneMerge) Line: 3877	
> 	ConcurrentMergeScheduler.doMerge(MergePolicy$OneMerge) Line: 205	
> 	ConcurrentMergeScheduler$MergeThread.run() Line: 260	
> Thread [Indexer] (Ausgesetzt)	
> 	Object.wait(long) Line: not available [native Methode]	
> 	IndexWriter.doWait() Line: 4491	
> 	IndexWriter.optimize(int, boolean) Line: 2268	
> 	IndexWriter.optimize(boolean) Line: 2203	
> 	IndexWriter.optimize() Line: 2183	
> 	Indexer.run() Line: 263	
> If you need more informations, please let me know.

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