I expect the answer to my question is simply "make sure model access
is synchronized", but just in case, I'm wondering whether this is
expected behavior. Here's some code that modifies a model from a
bunch of different threads. This doesn't cause an error every time,
but occasionally throws, as shown in the stacktrace following the
code.
The class here is called OhDearTest, because I getting a
`jena.shared.BrokenException oh dear, already have a slot for ...`
earlier, which I'm still trying to reproduce. This code doesn't seem
to trigger it. I've included a bit of that stacktrace at the very end.
## Code
import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;
import org.apache.jena.rdf.model.Property;
import org.apache.jena.rdf.model.Resource;
public class OhDearTest {
public static void main(String[] args) throws InterruptedException {
int n = 1000;
Model model = ModelFactory.createDefaultModel();
Property p = model.createProperty("urn:ex:p");
Thread[] thread = new Thread[n];
for (int i = 0; i < n; i++) {
thread[i] = new Thread(() -> {
Resource r = model.createResource();
r.addLiteral(p, "value");
});
thread[i].start();
}
for (int i = 0; i < n; i++) {
thread[i].join();
}
}
}
## Stacktrace
Exception in thread "Thread-300" Exception in thread "Thread-299"
Exception in thread "Thread-304" Exception in thread "Thread-282"
Exception in thread "Thread-324" Exception in thread "Thread-331"
Exception in thread "Thread-328"
java.lang.ArrayIndexOutOfBoundsException: 905
at org.apache.jena.mem.HashCommon.findSlot(HashCommon.java:164)
at org.apache.jena.mem.HashedTripleBunch.contains(HashedTripleBunch.java:40)
at org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:52)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:63)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addLiteral(ResourceImpl.java:285)
at OhDearTest.lambda$0(OhDearTest.java:15)
at java.lang.Thread.run(Thread.java:745)
java.lang.ArrayIndexOutOfBoundsException: 789
at org.apache.jena.mem.HashCommon.findSlot(HashCommon.java:164)
at org.apache.jena.mem.HashedTripleBunch.contains(HashedTripleBunch.java:40)
at org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:52)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:63)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addLiteral(ResourceImpl.java:285)
at OhDearTest.lambda$0(OhDearTest.java:15)
at java.lang.Thread.run(Thread.java:745)
java.lang.ArrayIndexOutOfBoundsException: 827
at org.apache.jena.mem.HashCommon.findSlot(HashCommon.java:164)
at org.apache.jena.mem.HashedTripleBunch.contains(HashedTripleBunch.java:40)
at org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:52)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:63)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addLiteral(ResourceImpl.java:285)
at OhDearTest.lambda$0(OhDearTest.java:15)
at java.lang.Thread.run(Thread.java:745)
java.lang.ArrayIndexOutOfBoundsException: 1061
at org.apache.jena.mem.HashCommon.findSlot(HashCommon.java:164)
at org.apache.jena.mem.HashedBunchMap.put(HashedBunchMap.java:66)
at org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:51)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:60)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addLiteral(ResourceImpl.java:285)
at OhDearTest.lambda$0(OhDearTest.java:15)
at java.lang.Thread.run(Thread.java:745)
java.lang.ArrayIndexOutOfBoundsException: 918
at org.apache.jena.mem.HashCommon.findSlot(HashCommon.java:164)
at org.apache.jena.mem.HashedBunchMap.get(HashedBunchMap.java:59)
at org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:50)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:60)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addLiteral(ResourceImpl.java:285)
at OhDearTest.lambda$0(OhDearTest.java:15)
at java.lang.Thread.run(Thread.java:745)
java.lang.ArrayIndexOutOfBoundsException: 1109
at org.apache.jena.mem.HashCommon.findSlot(HashCommon.java:164)
at org.apache.jena.mem.HashedBunchMap.get(HashedBunchMap.java:59)
at org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:50)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:60)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addLiteral(ResourceImpl.java:285)
at OhDearTest.lambda$0(OhDearTest.java:15)
at java.lang.Thread.run(Thread.java:745)
java.lang.ArrayIndexOutOfBoundsException: 1144
at org.apache.jena.mem.HashedBunchMap.put$(HashedBunchMap.java:87)
at org.apache.jena.mem.HashedBunchMap.put(HashedBunchMap.java:70)
at org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:51)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:60)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addLiteral(ResourceImpl.java:285)
at OhDearTest.lambda$0(OhDearTest.java:15)
at java.lang.Thread.run(Thread.java:745)
## The Oh Dear Exception
The code above doesn't seem to produce this, but it's what I initially ran into.
Caused by: org.apache.jena.shared.BrokenException: oh dear, already
have a slot for 24e48338:15b5d4bfe76:-7ff3, viz 13
at org.apache.jena.mem.HashedBunchMap.grow(HashedBunchMap.java:109)
at org.apache.jena.mem.HashedBunchMap.put$(HashedBunchMap.java:90)
at org.apache.jena.mem.HashedBunchMap.put(HashedBunchMap.java:70)
at
org.apache.jena.mem.NodeToTriplesMapMem.add(NodeToTriplesMapMem.java:51)
at
org.apache.jena.mem.GraphTripleStoreBase.add(GraphTripleStoreBase.java:60)
at org.apache.jena.mem.GraphMem.performAdd(GraphMem.java:37)
at org.apache.jena.graph.impl.GraphBase.add(GraphBase.java:181)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:1191)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:184)
at org.apache.jena.rdf.model.impl.ModelCom.add(ModelCom.java:172)
at
org.apache.jena.rdf.model.impl.ResourceImpl.addProperty(ResourceImpl.java:263)
--
Joshua Taylor, http://www.cs.rpi.edu/~tayloj/
