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https://issues.apache.org/jira/browse/JCR-3440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13476145#comment-13476145
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Bart van der Schans commented on JCR-3440:
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Hi Luca,
>From what I see in the code the read operations also start a batched operation
>which I don't think is needed. This was introduced (by accident) as a fix for
>reading large journals in JCR-2832 by Jukka. This lead to problems that the
>batchmode was started twice: once in the doLock() method, called in
>internalLockandSync (for write operations) and by the doSync(long
>startRevision) in the DatabaseJournal. The doSync(long startRevision) is also
>called for the read only operations by the internalSync() method. Hence since
>then all read operations start transactions as well.
The double transaction start was fixed in JCR-2882, but the actual fix should
have been to not start a batch mode in the doSync(long startRevision) at all.
Could you try the attached patch and check if you can still reproduce the
deadlock?
Bart
> Deadlock on LOCAL_REVISION table in clustering environment
> ----------------------------------------------------------
>
> Key: JCR-3440
> URL: https://issues.apache.org/jira/browse/JCR-3440
> Project: Jackrabbit Content Repository
> Issue Type: Bug
> Components: clustering
> Affects Versions: 2.4.3
> Environment: Env.1: 4x Linux server CentOS 5 MSSQL 2008 database
> (production system)
> Env.2: 2x Linux Ubuntu 10.04 server tested with PostgreSQL 9.1, H2, MSSQL
> 2008 and mySQL 5.5 (lab system)
> Reporter: Luca Tagliani
> Priority: Critical
> Attachments: fixAlwaysBatchMode.patch, JCR-3440.patch,
> threadDump-JCR-3440.txt
>
>
> When inserting a lot of nodes concurrently (100/200 threads) the system hangs
> generating a deadlock on the LOCAL_REVISION table.
> There is a thread that starts a transaction but the transaction remains open,
> while another thread tries to acquire the lock on the table.
> This actually happen even if there is only a server up but configured in
> cluster mode.
> I found that in AbstractJournal, we try to write the LOCAL_REVISION even if
> we don't sync any record because they're generated by the same journal of the
> thread running.
> Removing this unnecessary (to me :-) ) write to the LOCAL_REVISION table,
> remove the deadlock.
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