Running DMN evaluation in parallel causes a ConcurrentModificationException --------------------------------------------------------------------------- Key: DROOLS-1715 URL: https://issues.jboss.org/browse/DROOLS-1715 Project: Drools Issue Type: Bug Components: dmn engine Affects Versions: 7.2.0.Final Reporter: David Le Moing Assignee: Matteo Mortari When launching some Parameterized tests in parallel, I noticed that I was not getting any answer (it works with only 1 thread). When I started digging, I found that the cause was a ConcurrentModificationException thrown when iterating over events in the processEvents method of DMNDTExpressionEvaluator. {code} at java.util.ConcurrentModificationException.<init>(ConcurrentModificationException.java:78) at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) at java.util.ArrayList$Itr.next(ArrayList.java:851) at org.kie.dmn.core.ast.DMNDTExpressionEvaluator.processEvents(DMNDTExpressionEvaluator.java:101) at org.kie.dmn.core.ast.DMNDTExpressionEvaluator.evaluate(DMNDTExpressionEvaluator.java:92) at org.kie.dmn.core.impl.DMNRuntimeImpl.evaluateDecision(DMNRuntimeImpl.java:337) at org.kie.dmn.core.impl.DMNRuntimeImpl.evaluateAll(DMNRuntimeImpl.java:92) {code}