When I tried to add a transaction on dest there was an error with a
transaction already being active.
Does the concurrent modification error indicate that the model was somehow
changed outside of an iterator? That is where I am used to seeing it.
The iterator call is in a recursive call to extractInfo().
Both graphs are in the same dataset.
all txnX() methods are of the form:
public static void txnBegin(Graph g) {
if (g.getTransactionHandler().transactionsSupported()) {
g.getTransactionHandler().begin();
}
}
Stepping through the extract code there is this method:
public void extractInto( Node root )
{
active.add( root );
Iterator<Triple> it = extractFrom.find( root, Node.ANY,
Node.ANY );
while (it.hasNext())
{
Triple t = it.next();
Node subRoot = t.getObject();
toUpdate.add( t );
if (! (active.contains( subRoot ) || b.stopAt( t )))
extractInto( subRoot );
}
}
}
When the toUpdate.add(t) is called the
DatasetControlMRSW$IteratorCheckNotConcurrent.eCount
is incremented.
I see in the code comments for IteratorCheckNotConcurrent that it expects
writer to be on a different thread than reader. Is there a way around that
restriction? I ask because all other graphs that I have tested work fine
when reading and writing on the same thread.
Thoughts?
Claude
On Fri, Dec 29, 2017 at 10:28 PM, Andy Seaborne <[email protected]> wrote:
> The exception says there is incorrect MRSW use of iterators in the test.
>
> Iterator checking is very old code and I believe it works reliably - it is
> not guaranteed to always catch errors though. That was never the claim.
>
> Too many details missing to say much else but I don't see any txn on dest.
>
> Andy
>
>
> On 29/12/17 13:10, Claude Warren wrote:
>
>> fair enough.
>>
>> I created a ContractTest for GraphTxnTDB and discovered a lot of issues
>> with transactions in the contract tests. I cleaned most of them up but am
>> left with the following:
>>
>> /**
>> * This test exposed that the update-existing-graph functionality was
>> broken
>> * if the target graph already contained any statements with a
>> subject S
>> * appearing as subject in the source graph - no further Spo
>> statements
>> were
>> * added.
>> */
>> @ContractTest
>> public void testPartialUpdate() {
>> Graph source = graphWith(producer.newInstance(), "a R b; b S
>> e");
>> Graph dest = graphWith(producer.newInstance(), "b R d");
>> txnBegin(source);
>> try {
>> GraphExtract e = new GraphExtract(TripleBoundary.st
>> opNowhere);
>> e.extractInto(dest, node("a"), source);
>> txnCommit(source);
>> }
>> catch (RuntimeException e)
>> {
>> txnRollback(source);
>> fail( e.getMessage() );
>>
>> }
>> txnBegin(source);
>> assertIsomorphic(
>> graphWith( "a R b; b S e; b R d"),
>> dest);
>> txnRollback(source);
>>
>> }
>>
>>
>> Notes:
>> graphWith populates the graph with the triples defined in the string
>> using a transaction.
>> txnRollback performs an abort if transactions are supported.
>>
>> The problem is that an exception is thrown in the extractInfo() call.
>>
>> java.util.ConcurrentModificationException: Iterator: started at 6, now 7
>> at
>> org.apache.jena.tdb.sys.DatasetControlMRSW.policyError(Datas
>> etControlMRSW.java:147)
>> at
>> org.apache.jena.tdb.sys.DatasetControlMRSW.access$000(Datase
>> tControlMRSW.java:32)
>> at
>> org.apache.jena.tdb.sys.DatasetControlMRSW$IteratorCheckNotC
>> oncurrent.checkIterConcurrentModification(DatasetControlMRSW.java:103)
>> at
>> org.apache.jena.tdb.sys.DatasetControlMRSW$IteratorCheckNotC
>> oncurrent.hasNext(DatasetControlMRSW.java:110)
>> at org.apache.jena.atlas.iterator.Iter$2.hasNext(Iter.java:265)
>> at org.apache.jena.atlas.iterator.Iter$2.hasNext(Iter.java:265)
>> at org.apache.jena.atlas.iterator.Iter.hasNext(Iter.java:886)
>> at
>> org.apache.jena.util.iterator.WrappedIterator.hasNext(Wrappe
>> dIterator.java:90)
>> at
>> org.apache.jena.graph.GraphExtract$Extraction.extractInto(
>> GraphExtract.java:80)
>> at
>> org.apache.jena.graph.GraphExtract$Extraction.extractInto(
>> GraphExtract.java:85)
>> at org.apache.jena.graph.GraphExtract.extractInto(GraphExtract.
>> java:52)
>> at
>> org.apache.jena.graph.GraphContractTest.testPartialUpdate(Gr
>> aphContractTest.java:1564)
>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>> at
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAcce
>> ssorImpl.java:62)
>> at
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMe
>> thodAccessorImpl.java:43)
>> at java.lang.reflect.Method.invoke(Method.java:498)
>> at
>> org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(
>> FrameworkMethod.java:45)
>> at
>> org.junit.internal.runners.model.ReflectiveCallable.run(Refl
>> ectiveCallable.java:15)
>> at
>> org.junit.runners.model.FrameworkMethod.invokeExplosively(Fr
>> ameworkMethod.java:42)
>> at
>> org.junit.internal.runners.statements.InvokeMethod.evaluate(
>> InvokeMethod.java:20)
>> at
>> org.junit.internal.runners.statements.RunAfters.evaluate(Run
>> Afters.java:30)
>> at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
>> at
>> org.xenei.junit.contract.ContractTestRunner.runChild(Contrac
>> tTestRunner.java:138)
>> at
>> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit
>> 4ClassRunner.java:47)
>> at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
>> at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
>> at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
>> at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
>> at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
>> at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
>> at
>> org.xenei.junit.contract.ContractSuite.runChild(ContractSuite.java:369)
>> at org.xenei.junit.contract.ContractSuite.runChild(ContractSuit
>> e.java:1)
>> at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
>> at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
>> at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
>> at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
>> at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
>> at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
>> at
>> org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.
>> run(JUnit4TestReference.java:86)
>> at
>> org.eclipse.jdt.internal.junit.runner.TestExecution.run(
>> TestExecution.java:38)
>> at
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTe
>> sts(RemoteTestRunner.java:459)
>> at
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTe
>> sts(RemoteTestRunner.java:678)
>> at
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(
>> RemoteTestRunner.java:382)
>> at
>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(
>> RemoteTestRunner.java:192)
>>
>> Is this a bug, or a known limitation of GraphTxnTDB?
>>
>> Claude
>>
>> On Fri, Dec 29, 2017 at 11:14 AM, Andy Seaborne <[email protected]> wrote:
>>
>> Try it :-)
>>>
>>> Then try running it twice in a JVM.
>>>
>>> And then try TDB2 vs TDB1 vs TIM.
>>>
>>> Andy
>>>
>>>
>>> On 28/12/17 23:49, Claude Warren wrote:
>>>
>>> Would the following code snippit work
>>>>
>>>> Graph g = // a TDB graph instance
>>>> if (g.getTransactionHandler().transactionsSupported()) {
>>>> Graph initial = graphWith( GraphFactory.createGraphMem(),
>>>> "initial hasValue 42; also hasURI hello");
>>>> Graph extra = graphWith(GraphFactory.createGraphMem(),
>>>> "extra hasValue 17; also hasURI world");
>>>> GraphUtil.addInto(g, initial);
>>>> g.getTransactionHandler().begin();
>>>> GraphUtil.addInto(g, extra);
>>>> g.getTransactionHandler().abort();
>>>> assertIsomorphic(initial, g);
>>>>
>>>>
>>>> Notes:
>>>> graphWith populates the graph with the triples defined in the
>>>> string.
>>>> GraphUtil.addInto() performs no transaction handling and copies
>>>> the
>>>> contents of the second param into the first param.
>>>>
>>>> I suspect that this will/should fail when the begin() is called as the
>>>> transaction as we are switching from not using transactions to using
>>>> them.
>>>>
>>>> Claude
>>>>
>>>>
>>>>
>>
>>
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