[
https://issues.apache.org/jira/browse/LUCENE-10583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17549375#comment-17549375
]
Thomas Hoffmann commented on LUCENE-10583:
------------------------------------------
Hello Vigya,
thanks for reporting back concerning this topic.
The method has a synchronized(MMapDirectory)
Within this block the IndexWriter is created, used and commited.
I read in the documentation at
[https://lucene.apache.org/core/7_4_0/core/org/apache/lucene/index/IndexWriter.html]
that the IndexWriter should not be used:
"you should *not* synchronize on the {{IndexWriter}} instance as this may cause
deadlock"
So as far as I got your reply, no Lucene-Object should be used for
synchronization (not just IndexWriter), right?
I already refactored the class and removed any synchronized-blocks with any
lucene object. This should solve the issue, right?
Maybe you can add the above mentioned warning also to the other classes which
might cause trouble. This might prevent that someone else
is also running into this trouble like me :)
Thank you very much!
Thomas
> Deadlock with MMapDirectory while waitForMerges
> -----------------------------------------------
>
> Key: LUCENE-10583
> URL: https://issues.apache.org/jira/browse/LUCENE-10583
> Project: Lucene - Core
> Issue Type: Bug
> Components: core/index
> Affects Versions: 8.11.1
> Environment: Java 17
> OS: Windows 2016
> Reporter: Thomas Hoffmann
> Priority: Critical
>
> Hello,
> a deadlock situation happened in our application. We are using MMapDirectory
> on Windows 2016 and got the following stacktrace:
> {code:java}
> "https-openssl-nio-443-exec-30" #166 daemon prio=5 os_prio=0 cpu=78703.13ms
> "https-openssl-nio-443-exec-30" #166 daemon prio=5 os_prio=0 cpu=78703.13ms
> elapsed=81248.18s tid=0x000000002860af10 nid=0x237c in Object.wait()
> [0x00000000413fc000]
> java.lang.Thread.State: TIMED_WAITING (on object monitor)
> at java.lang.Object.wait(java.base@17.0.2/Native Method)
> - waiting on <no object reference available>
> at org.apache.lucene.index.IndexWriter.doWait(IndexWriter.java:4983)
> - locked <0x00000006ef1fc020> (a org.apache.lucene.index.IndexWriter)
> at
> org.apache.lucene.index.IndexWriter.waitForMerges(IndexWriter.java:2697)
> - locked <0x00000006ef1fc020> (a org.apache.lucene.index.IndexWriter)
> at org.apache.lucene.index.IndexWriter.shutdown(IndexWriter.java:1236)
> at org.apache.lucene.index.IndexWriter.close(IndexWriter.java:1278)
> at
> com.speed4trade.ebs.module.search.SearchService.updateSearchIndex(SearchService.java:1723)
> - locked <0x00000006d5c00208> (a org.apache.lucene.store.MMapDirectory)
> at
> com.speed4trade.ebs.module.businessrelations.ticket.TicketChangedListener.postUpdate(TicketChangedListener.java:142)
> ...{code}
> All threads were waiting to lock <0x00000006d5c00208> which got never
> released.
> A lucene thread was also blocked, I dont know if this is relevant:
> {code:java}
> "Lucene Merge Thread #0" #18466 daemon prio=5 os_prio=0 cpu=15.63ms
> elapsed=3499.07s tid=0x00000000459453e0 nid=0x1f8 waiting for monitor entry
> [0x000000005da9e000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.lucene.store.FSDirectory.deletePendingFiles(FSDirectory.java:346)
> - waiting to lock <0x00000006d5c00208> (a
> org.apache.lucene.store.MMapDirectory)
> at
> org.apache.lucene.store.FSDirectory.maybeDeletePendingFiles(FSDirectory.java:363)
> at org.apache.lucene.store.FSDirectory.createOutput(FSDirectory.java:248)
> at
> org.apache.lucene.store.LockValidatingDirectoryWrapper.createOutput(LockValidatingDirectoryWrapper.java:44)
> at
> org.apache.lucene.index.ConcurrentMergeScheduler$1.createOutput(ConcurrentMergeScheduler.java:289)
> at
> org.apache.lucene.store.TrackingDirectoryWrapper.createOutput(TrackingDirectoryWrapper.java:43)
> at
> org.apache.lucene.codecs.compressing.CompressingStoredFieldsWriter.<init>(CompressingStoredFieldsWriter.java:121)
> at
> org.apache.lucene.codecs.compressing.CompressingStoredFieldsFormat.fieldsWriter(CompressingStoredFieldsFormat.java:130)
> at
> org.apache.lucene.codecs.lucene87.Lucene87StoredFieldsFormat.fieldsWriter(Lucene87StoredFieldsFormat.java:141)
> at
> org.apache.lucene.index.SegmentMerger.mergeFields(SegmentMerger.java:227)
> at org.apache.lucene.index.SegmentMerger.merge(SegmentMerger.java:105)
> at org.apache.lucene.index.IndexWriter.mergeMiddle(IndexWriter.java:4757)
> at org.apache.lucene.index.IndexWriter.merge(IndexWriter.java:4361)
> at
> org.apache.lucene.index.IndexWriter$IndexWriterMergeSource.merge(IndexWriter.java:5920)
> at
> org.apache.lucene.index.ConcurrentMergeScheduler.doMerge(ConcurrentMergeScheduler.java:626)
> at
> org.apache.lucene.index.ConcurrentMergeScheduler$MergeThread.run(ConcurrentMergeScheduler.java:684){code}
> If looks like the merge operation never finished and released the lock.
> Is there any option to prevent this deadlock or how to investigate it further?
> A load-test didn't show this problem unfortunately.
--
This message was sent by Atlassian Jira
(v8.20.7#820007)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org
For additional commands, e-mail: issues-h...@lucene.apache.org
