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Posted to dev@jackrabbit.apache.org by "Jukka Zitting (JIRA)" <ji...@apache.org> on 2009/03/05 19:17:56 UTC
[jira] Reopened: (JCR-2000) Deadlock on concurrent commits
[ https://issues.apache.org/jira/browse/JCR-2000?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jukka Zitting reopened JCR-2000:
--------------------------------
One more thing, detected in a test run I left for the night. The VersionItemStateProvider.hasNodeReferences() call inside the scope of a workspace lock conflicts with the versioning lock held by another thread. The conflict can be seen in the following thread dump:
HOLDS WORKSPACE LOCK, WAITS FOR VERSIONING LOCK
"Thread-577" prio=10 tid=0x0859ac00 nid=0x6e86 in Object.wait() [0xa487a000..0xa487af20]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0xad082b20> (a EDU.oswego.cs.dl.util.concurrent.WriterPreferenceReadWriteLock$ReaderLock)
at java.lang.Object.wait(Object.java:485)
at EDU.oswego.cs.dl.util.concurrent.WriterPreferenceReadWriteLock$ReaderLock.acquire(Unknown Source)
- locked <0xad082b20> (a EDU.oswego.cs.dl.util.concurrent.WriterPreferenceReadWriteLock$ReaderLock)
at org.apache.jackrabbit.core.state.DefaultISMLocking$ReadLockImpl.<init>(DefaultISMLocking.java:86)
at org.apache.jackrabbit.core.state.DefaultISMLocking$ReadLockImpl.<init>(DefaultISMLocking.java:80)
at org.apache.jackrabbit.core.state.DefaultISMLocking.acquireReadLock(DefaultISMLocking.java:44)
at org.apache.jackrabbit.core.state.SharedItemStateManager.acquireReadLock(SharedItemStateManager.java:1403)
at org.apache.jackrabbit.core.state.SharedItemStateManager.hasNodeReferences(SharedItemStateManager.java:350)
at org.apache.jackrabbit.core.version.VersionItemStateProvider.hasNodeReferences(VersionItemStateProvider.java:142)
at org.apache.jackrabbit.core.state.SharedItemStateManager.hasNodeReferences(SharedItemStateManager.java:369)
at org.apache.jackrabbit.core.state.SharedItemStateManager$Update.addReference(SharedItemStateManager.java:898)
at org.apache.jackrabbit.core.state.SharedItemStateManager$Update.addReferences(SharedItemStateManager.java:883)
at org.apache.jackrabbit.core.state.SharedItemStateManager$Update.updateReferences(SharedItemStateManager.java:866)
at org.apache.jackrabbit.core.state.SharedItemStateManager$Update.begin(SharedItemStateManager.java:560)
at org.apache.jackrabbit.core.state.SharedItemStateManager.beginUpdate(SharedItemStateManager.java:1056)
at org.apache.jackrabbit.core.state.SharedItemStateManager.update(SharedItemStateManager.java:1086)
at org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:337)
at org.apache.jackrabbit.core.state.XAItemStateManager.update(XAItemStateManager.java:347)
at org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:312)
at org.apache.jackrabbit.core.state.SessionItemStateManager.update(SessionItemStateManager.java:313)
at org.apache.jackrabbit.core.ItemImpl.save(ItemImpl.java:1105)
- locked <0xb0cc9e00> (a org.apache.jackrabbit.core.XASessionImpl)
at org.apache.jackrabbit.core.SessionImpl.save(SessionImpl.java:846)
at org.apache.jackrabbit.core.NodeImpl.checkout(NodeImpl.java:3340)
at org.apache.jackrabbit.core.ConcurrentVersioningWithTransactionsTest$2.execute(ConcurrentVersioningWithTransactionsTest.java:119)
at org.apache.jackrabbit.core.AbstractConcurrencyTest$Executor.run(AbstractConcurrencyTest.java:164)
at java.lang.Thread.run(Thread.java:619)
HOLDS VERSIONING LOCK, WAITS FOR WORKSPACE LOCK
"Thread-571" prio=10 tid=0xa7991400 nid=0x6e80 in Object.wait() [0xa4ddb000..0xa4ddbe20]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0xad082c28> (a EDU.oswego.cs.dl.util.concurrent.WriterPreferenceReadWriteLock$WriterLock)
at java.lang.Object.wait(Object.java:485)
at EDU.oswego.cs.dl.util.concurrent.WriterPreferenceReadWriteLock$WriterLock.acquire(Unknown Source)
- locked <0xad082c28> (a EDU.oswego.cs.dl.util.concurrent.WriterPreferenceReadWriteLock$WriterLock)
at org.apache.jackrabbit.core.state.DefaultISMLocking$1.<init>(DefaultISMLocking.java:55)
at org.apache.jackrabbit.core.state.DefaultISMLocking.acquireWriteLock(DefaultISMLocking.java:52)
at org.apache.jackrabbit.core.state.SharedItemStateManager.acquireWriteLock(SharedItemStateManager.java:1419)
at org.apache.jackrabbit.core.state.SharedItemStateManager.access$200(SharedItemStateManager.java:116)
at org.apache.jackrabbit.core.state.SharedItemStateManager$Update.begin(SharedItemStateManager.java:547)
at org.apache.jackrabbit.core.state.SharedItemStateManager.beginUpdate(SharedItemStateManager.java:1056)
at org.apache.jackrabbit.core.state.XAItemStateManager.prepare(XAItemStateManager.java:156)
at org.apache.jackrabbit.core.TransactionContext.prepare(TransactionContext.java:154)
- locked <0xb0f06868> (a org.apache.jackrabbit.core.TransactionContext)
at org.apache.jackrabbit.core.XASessionImpl.prepare(XASessionImpl.java:324)
at org.apache.jackrabbit.core.UserTransactionImpl.commit(UserTransactionImpl.java:121)
at org.apache.jackrabbit.core.ConcurrentVersioningWithTransactionsTest$2.execute(ConcurrentVersioningWithTransactionsTest.java:117)
at org.apache.jackrabbit.core.AbstractConcurrencyTest$Executor.run(AbstractConcurrencyTest.java:164)
at java.lang.Thread.run(Thread.java:619)
The VersionItemStateManager already avoids this conflict in the way it overrides the setNodeReferences() method, but it should do the same also for the get/hasNodeReferences() methods that are invoked by SharedItemStateManager when persisting normal workspace content.
> Deadlock on concurrent commits
> ------------------------------
>
> Key: JCR-2000
> URL: https://issues.apache.org/jira/browse/JCR-2000
> Project: Jackrabbit Content Repository
> Issue Type: Bug
> Components: jackrabbit-core, transactions
> Affects Versions: 1.5.3
> Reporter: Jukka Zitting
> Assignee: Jukka Zitting
> Fix For: 1.5.4
>
> Attachments: JCR-2000.patch, JCR-2000.patch, search-on-sism.patch, thread-join.patch
>
>
> As reported in the followup to JCR-1979, there's a case where two transactions may be concurrently inside a commit. This is bad as it breaks the main assumption in http://jackrabbit.apache.org/concurrency-control.html about all transactions first acquiring the versioning write lock.
> Looking deeper into this I find that the versioning write lock is only acquired if the transaction being committed contains versioning operations. This is incorrect as all transactions in any case need to access the version store when checking for references.
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