The reason is: for creating/deleting a relationship both end-nodes are locked
and if you have one thread locking a, then trying b while another does b, then tries a, none can proceed and one of the transactions will be killed with a deadlock exception. Update to 3.0.4 recommended is to retry the query otherwise: * you can try to lock on a well known lock node to serialize that kind of access, you can either lock via removing a non-existing property, .e.g. REMOVE rootNode.__lock__ or with APOC's lock procedures * sort, group, batch your updates so that you always update one subgraph in one tx so that there are no conflicting updates in two different transactions. Michael > Am 02.09.2016 um 03:00 schrieb Ray Chengr <chengr...@gmail.com>: > > We're using Python 3.4.3, py2neo 2.0.8, Neo4j 3.0.3, on a 12 x 2.6GHz 96GB > RAM box. Our relationship & node insertion rate is about 100+ per second. > From time to time I saw this kind of error on neo4j.log. Is there anything we > can do such as from neo4j.com to avoid this kind of error? > > ERROR Failed to commit transaction. LockClient[5498051] can't wait on > resource RWLock[RELATIONSHIP(2009573), hash=942147114] since => > LockClient[5498051] <-[:HELD_BY]- RWLock[RELATIONSHIP(2009572), > hash=1901714492] <-[:WAITING_FOR]- LockClient[5498052] <-[:HELD_BY]- > RWLock[RELATIONSHIP(2009573), hash=942147114] > org.neo4j.kernel.DeadlockDetectedException: LockClient[5498051] can't wait on > resource RWLock[RELATIONSHIP(2009573), hash=942147114] since => > LockClient[5498051] <-[:HELD_BY]- RWLock[RELATIONSHIP(2009572), > hash=1901714492] <-[:WAITING_FOR]- LockClient[5498052] <-[:HELD_BY]- > RWLock[RELATIONSHIP(2009573), hash=942147114] > at > org.neo4j.kernel.impl.locking.community.RagManager.checkWaitOnRecursive(RagManager.java:198) > at > org.neo4j.kernel.impl.locking.community.RagManager.checkWaitOnRecursive(RagManager.java:225) > at > org.neo4j.kernel.impl.locking.community.RagManager.checkWaitOn(RagManager.java:165) > at > org.neo4j.kernel.impl.locking.community.RWLock.acquireWriteLock(RWLock.java:375) > at > org.neo4j.kernel.impl.locking.community.LockManagerImpl.getWriteLock(LockManagerImpl.java:55) > at > org.neo4j.kernel.impl.locking.community.CommunityLockClient.acquireExclusive(CommunityLockClient.java:142) > at > org.neo4j.kernel.impl.transaction.state.RelationshipCreator.connect(RelationshipCreator.java:202) > > Thanks, > Ray > > -- > You received this message because you are subscribed to the Google Groups > "Neo4j" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to neo4j+unsubscr...@googlegroups.com > <mailto:neo4j+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "Neo4j" group. To unsubscribe from this group and stop receiving emails from it, send an email to neo4j+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
