Johan,
I tried your second suggestion but unfortunately, I am running into the same
dead-lock, only this time while calling LockManager.getWriteLock(). I pasted
how I am using this feature and below the new exception output. Is the usage
maybe incorrect? Note, that I rely on Spring transactions, which appears to
work just fine regarding the release.
public void aquireTransactionalWriteLock(Node node) {
LockReleaser lockReleaser =
embeddedNeoService.getConfig().getLockReleaser();
lockReleaser.addLockToTransaction(node, LockType.WRITE);
LockManager lockManager =
embeddedNeoService.getConfig().getLockManager();
lockManager.getWriteLock(node);
}
Thanks,
-Andreas
vvvvvv
org.neo4j.impl.transaction.DeadlockDetectedException:
Transaction[Status=STATUS_ACTIVE,ResourceList=Xid[GlobalId[NEOKERNL|1257353507304|1887584],
BranchId
[ 49 54 50 51 55 51 ]]
xaresource[org.neo4j.util.index.lucenexaconnection$lucenexaresou...@1b65dd9]
Status[ENLISTED],Xid[GlobalId[NEOKERNL|1257353507304|1
887584], BranchId[ 52 49 52 49 52 49 ]]
xaresource[org.neo4j.impl.nioneo.xa.neostorexaconnection$neostorexaresou...@1cb83ad]
Status[ENLISTED] can't wait o
n resource RWLock[Node[310788]] since =>
Transaction[Status=STATUS_ACTIVE,ResourceList=Xid[GlobalId[NEOKERNL|1257353507304|1887584],
BranchId[ 49 54 50 51
55 51 ]]
xaresource[org.neo4j.util.index.lucenexaconnection$lucenexaresou...@1b65dd9]
Status[ENLISTED],Xid[GlobalId[NEOKERNL|1257353507304|1887584], Bran
chId[ 52 49 52 49 52 49 ]]
xaresource[org.neo4j.impl.nioneo.xa.neostorexaconnection$neostorexaresou...@1cb83ad]
Status[ENLISTED] <- RWLock[Node[302033]] <
-
Transaction[Status=STATUS_ACTIVE,ResourceList=Xid[GlobalId[NEOKERNL|1257353507304|1887584],
BranchId[ 49 54 50 51 55 51 ]] XAResource[org.neo4j.util.ind
ex.lucenexaconnection$lucenexaresou...@1b65dd9]
Status[ENLISTED],Xid[GlobalId[NEOKERNL|1257353507304|1887584], BranchId[ 52 49
52 49 52 49 ]] XAResource[o
rg.neo4j.impl.nioneo.xa.neostorexaconnection$neostorexaresou...@1cb83ad]
Status[ENLISTED] <- RWLock[Node[310788]]
at
org.neo4j.impl.transaction.RagManager.checkWaitOnRecursive(RagManager.java:208)
at
org.neo4j.impl.transaction.RagManager.checkWaitOnRecursive(RagManager.java:236)
at
org.neo4j.impl.transaction.RagManager.checkWaitOn(RagManager.java:176)
at org.neo4j.impl.transaction.RWLock.acquireWriteLock(RWLock.java:298)
at
org.neo4j.impl.transaction.LockManager.getWriteLock(LockManager.java:122)
> -----Ursprüngliche Nachricht-----
> Von: "Johan Svensson" <[email protected]>
> Gesendet: 03.11.09 15:16:18
> An: Neo user discussions <[email protected]>
> Betreff: Re: [Neo] Infrequent DeadlockDetectedException
> Lock handling has not been exposed in the real API (yet) but you can
> still access the internal lock manager. Here is an example on how to
> do it:
>
> // get lock manager
> LockManager lockManager = ((EmbeddedNeo)
> neo).getConfig().getLockManager();
>
> // start transaction that sometimes deadlocks with other transactions
> Transaction tx = neo.beginTx();
>
> // first thing we do is grab a write lock on something,
> // for example a node (the other transactions then have to
> lock on same node)
> lockManager.getWriteLock( node );
>
> // perform work that previously deadlocked
>
> // release write lock
> lockManager.releaseWriteLock( node );
>
> // commit transaction
> tx.success();
> tx.finish();
>
> There exist a "lock releaser" adding the lock to the running
> transaction. The lock will then be released upon commit or rollback of
> the transaction:
>
> Transaction tx = neo.beginTx();
> lockManager.getWriteLock( node );
>
> // add write lock on node to transaction
> LockReleaser lockReleaser = ((EmbeddedNeo)
> neo).getConfig().getLockReleaser();
> lockManager.addLockToTransaction( node, LockType.WRITE );
>
> // perform work, lock will be released on commit/rollback
>
> Hope this helps.
>
> Regards,
> -Johan
>
> On Tue, Nov 3, 2009 at 12:49 AM, Andreas Guenther
> <[email protected]> wrote:
> > Johan,
> >
> > I like to consider the node lock idea. Can you provide a quick code
> > snippet on the recommended approach for this?
> >
> > Thank you in advance,
> > -Andreas
> >
> > Johan Svensson wrote:
> >> On Mon, Nov 2, 2009 at 9:06 PM, Andreas Guenther
> >> <[email protected]> wrote:
> >>
> >>> Hi,
> >>>
> >>> I am getting the below deadlock exception occasionally and so far only
> >>> on relationship operations. The code base is trunk. The system this is
> >>> running on is Linux and the Java app integrates Neo with Spring
> >>> transaction manager. Multiple threads are actively updating the Neo
> >>> storage in different ways. The only way for us to currently mitigate
> >>> this problem is to retry the entire transaction call around this, but
> >>> this only succeeds to 99%. I am using the LuceneIndexer to store a
> >>> simple Long ID value representing a node in case that helps based on the
> >>> exception message.
> >>>
> >>> I am currently thinking how to best extract this problem into a little
> >>> unit test but based on how often this happens, I haven't been able to
> >>> reproduce it in a self-contained test suite.
> >>>
> >>> Any suggestions on how to get this under control?
> >>>
> >>>
> >>
> >> Hi,
> >>
> >> Looks like a standard deadlock, two or more transactions try to modify
> >> the same data and end up in a deadlock. There are several ways to get
> >> around this. I would suggest either do some external synchronization
> >> at the beginning of the transaction (for example get a write lock on a
> >> node so transactions will execute after each other instead of race
> >> towards a potential deadlock) or modify the "node space" layout so
> >> there is a lower chance of transactions waiting on each other (similar
> >> to lock striping but you do it by having a different layout of the
> >> graph).
> >>
> >> Regards,
> >> -Johan
> _______________________________________________
> Neo mailing list
> [email protected]
> https://lists.neo4j.org/mailman/listinfo/user
>
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