Simon,
It's probably in 2.7.4 as well.
I've improved the code based on the stacktrace and on code analysis.
It'll be in tonight's build. It now tracks when the write transaction
is active or is no longer subject to change (the latter is when the
error is occuring)
If it is what I think it is, then a test case will need one transaction
committed and queued in the journal and then at least two transactions
(2 read or 1 read, 1 write) concurrently active all on the same area of
the graph. The stack trace has at least 2 write transactions committed
and queued; either 2 and it's a writer or 3 and it's a reader.
(Or there is concurrent access inside one active transaction in which
case all bets are off.)
It would be possible to remove the block tracking but I'd rather not.
Such internal details as operations tracking can be useful and it is
hard to retro fit later.
Andy
On 15/10/12 18:28, Simon Helsen wrote:
Hi everyone,
in some of our testing, we are still working with 2.7.1, so I am trying to
figure out if the issue observed might be fixed in 2.7.4 or not, or, if we
are making a mistake ourselves. I don't have a test case right now because
the problem only surfaced in a heavy-duty (200+ clients) 5-day reliability
test. So, I currently have no idea about the circumstances or even a hint
on how to reproduce, but perhaps someone will recognize this issue. I
suspect the problem is caused by our usage of
At some point in our code (this is in the SecuringFilter.getPropertyFor
you see below in the stack trace), we have this
results = this.datasetGraphTransaction.find(graphNode, Node.ANY, property,
Node.ANY);
where
this.datasetGraphTransaction = (DatasetGraphTransaction)
(queryContext.getDataset().asDatasetGraph());
is created at the beginning of the transaction. Everything you see below
sits in a read transaction.
I also looked at the code in BlockMgrJournal and I am not sure what the
purpose is of final private Set<Long> iteratorBlocks = new HashSet<Long>()
; in which the concurrent mod seems to happen. Is it only for logging
purposes?
thanks
Simon
Caused by: java.util.ConcurrentModificationException
at
java.util.HashMap$AbstractMapIterator.checkConcurrentMod(HashMap.java:122)
at java.util.HashMap$AbstractMapIterator.makeNext(HashMap.java:127)
at java.util.HashMap$KeyIterator.next(HashMap.java:200)
at java.util.HashMap.analyzeMap(HashMap.java:724)
at java.util.HashMap.rehash(HashMap.java:710)
at java.util.HashMap.rehash(HashMap.java:743)
at java.util.HashMap.putImpl(HashMap.java:629)
at java.util.HashMap.put(HashMap.java:607)
at java.util.HashSet.add(HashSet.java:95)
at
com.hp.hpl.jena.tdb.transaction.BlockMgrJournal.getReadIterator(BlockMgrJournal.java:149)
at
com.hp.hpl.jena.tdb.transaction.BlockMgrJournal.getReadIterator(BlockMgrJournal.java:146)
at
com.hp.hpl.jena.tdb.base.block.BlockMgrWrapper.getReadIterator(BlockMgrWrapper.java:58)
at
com.hp.hpl.jena.tdb.base.recordbuffer.RecordBufferPageMgr.getReadIterator(RecordBufferPageMgr.java:53)
at com.hp.hpl.jena.tdb.base.recordbuffer.RecordRangeIterator.<init>
(RecordRangeIterator.java:82)
at
com.hp.hpl.jena.tdb.base.recordbuffer.RecordRangeIterator.iterator(RecordRangeIterator.java:40)
at
com.hp.hpl.jena.tdb.index.bplustree.BPlusTree.iterator(BPlusTree.java:383)
at
com.hp.hpl.jena.tdb.index.bplustree.BPlusTree.iterator(BPlusTree.java:366)
at
com.hp.hpl.jena.tdb.index.TupleIndexRecord.findWorker(TupleIndexRecord.java:164)
at
com.hp.hpl.jena.tdb.index.TupleIndexRecord.findOrScan(TupleIndexRecord.java:84)
at
com.hp.hpl.jena.tdb.index.TupleIndexRecord.performFind(TupleIndexRecord.java:78)
at
com.hp.hpl.jena.tdb.index.TupleIndexBase.find(TupleIndexBase.java:91)
at com.hp.hpl.jena.tdb.index.TupleTable.find(TupleTable.java:172)
at
com.hp.hpl.jena.tdb.nodetable.NodeTupleTableConcrete.find(NodeTupleTableConcrete.java:169)
at
com.hp.hpl.jena.tdb.nodetable.NodeTupleTableConcrete.find(NodeTupleTableConcrete.java:157)
at
com.hp.hpl.jena.tdb.nodetable.NodeTupleTableConcrete.findAsNodeIds(NodeTupleTableConcrete.java:146)
at com.hp.hpl.jena.tdb.store.QuadTable.find(QuadTable.java:87)
at
com.hp.hpl.jena.tdb.store.DatasetGraphTDB.findInSpecificNamedGraph(DatasetGraphTDB.java:108)
at
com.hp.hpl.jena.sparql.core.DatasetGraphBaseFind.findNG(DatasetGraphBaseFind.java:59)
at
com.hp.hpl.jena.sparql.core.DatasetGraphBaseFind.find(DatasetGraphBaseFind.java:48)
at
com.hp.hpl.jena.tdb.migrate.DatasetGraphTrackActive.find(DatasetGraphTrackActive.java:165)
at
com.ibm.team.jfs.rdf.internal.jena.SecuringFilter.getPropertyFor(SecuringFilter.java:156)
at
com.ibm.team.jfs.rdf.internal.jena.SecuringFilter.getContextFor(SecuringFilter.java:149)
at
com.ibm.team.jfs.rdf.internal.jena.SecuringFilter.checkContextFor(SecuringFilter.java:136)
at
com.ibm.team.jfs.rdf.internal.jena.SecuringFilter.accept(SecuringFilter.java:94)
at
com.ibm.team.jfs.rdf.internal.jena.SecuringFilter.accept(SecuringFilter.java:1)
at org.openjena.atlas.iterator.Iter$3.hasNext(Iter.java:187)
at org.openjena.atlas.iterator.Iter$6.hasNext(Iter.java:386)
at org.openjena.atlas.iterator.Iter$3.hasNext(Iter.java:181)
at org.openjena.atlas.iterator.Iter$4.hasNext(Iter.java:295)
at org.openjena.atlas.iterator.Iter$3.hasNext(Iter.java:181)
at org.openjena.atlas.iterator.Iter.hasNext(Iter.java:808)
at
org.openjena.atlas.iterator.RepeatApplyIterator.hasNext(RepeatApplyIterator.java:58)
at org.openjena.atlas.iterator.Iter$4.hasNext(Iter.java:295)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIterPlainWrapper.hasNextBinding(QueryIterPlainWrapper.java:54)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorBase.hasNext(QueryIteratorBase.java:108)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIterRepeatApply.makeNextStage(QueryIterRepeatApply.java:106)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIterRepeatApply.hasNextBinding(QueryIterRepeatApply.java:65)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorBase.hasNext(QueryIteratorBase.java:108)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIterConvert.hasNextBinding(QueryIterConvert.java:65)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorBase.hasNext(QueryIteratorBase.java:108)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorWrapper.hasNextBinding(QueryIteratorWrapper.java:40)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorBase.hasNext(QueryIteratorBase.java:108)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorWrapper.hasNextBinding(QueryIteratorWrapper.java:40)
at
com.hp.hpl.jena.sparql.engine.iterator.QueryIteratorBase.hasNext(QueryIteratorBase.java:108)
at
com.hp.hpl.jena.sparql.engine.ResultSetStream.hasNext(ResultSetStream.java:72)
at com.ibm.team.jfs.rdf.internal.jena.InternalResultSet.<init>
(InternalResultSet.java:26)
at
com.ibm.team.jfs.rdf.internal.jena.tdb.JenaTxTdbProvider.performSelect(JenaTxTdbProvider.java:1396)
at
com.ibm.team.jfs.rdf.internal.jena.tdb.JenaTxTdbProvider$15.run(JenaTxTdbProvider.java:1541)
at
com.ibm.team.jfs.rdf.internal.jena.tdb.JenaTxTdbProvider$15.run(JenaTxTdbProvider.java:1)
at
com.ibm.team.jfs.rdf.internal.jena.tdb.JenaTxTdbProvider.storeOperation(JenaTxTdbProvider.java:1968)
