[jira] [Commented] (LUCENE-5407) Deadlock? while indexing in cascaded threads

["Simon Willnauer (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-5407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13878397#comment-13878397 ] 

Simon Willnauer commented on LUCENE-5407:
-----------------------------------------

There is no way this would work here. Your first thread enters the index writer and gets a threadstate and then once it pulls the fields reader you enter the indexwriter again to add a "sub-document". This sub-document IW#addDocument call tries to get a thread-state as well but since there are only 8 ThreadStates by default you run into a deadlock since for the "parent-doc" thread to make progress the "sub-documents" thread must return from IW#addDocument but it can't since it waits for another thread to release one of the ThreadStates. So yes that is a deadlock situation but I really don't see any way this could work. I guess further this approach is not what I recommend you do anyways. If you want to index those documents in a stream then I guess a "producer -> queue -> consumer" approach might be best suited.  

> Deadlock? while indexing in cascaded threads
> --------------------------------------------
>
>                 Key: LUCENE-5407
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5407
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: core/index
>    Affects Versions: 4.6
>         Environment: Windows 7 64 bits, JRE 1.7.0_25 64 bits
>            Reporter: Luis Filipe Nassif
>         Attachments: Test.java, thread_dump.txt
>
>
> Apparently I found a deadlock problem with IndexWriter in a cascaded thread design to add documents (I am working on an application integrating Tika, which has the capability to add embedded documents to the index as independent documents as they are found). The attached code illustrates the problem. Sometimes it stops processing, at least one of the threads remains in WAITING state. It must be executed no more than 5 times in my environment to trigger the problem.



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