Platform BZ for Jira https://issues.jboss.org/browse/DROOLS-551
There is an issue in Drools 6, both in PHREAK and RETEOO mode, which causes NPEs to be thrown when a session is serialized and deserialized.
The problem occurs when running a stateful KieSession in STREAM mode and using Events with @expires annotations. When you insert an event with an @expires annotation, and you explicitly retract that Event again from the engine (i.e. KieSession.delete), and after that serialize the session, you end up with an invalid serialized session.
When you later deserialize the session, and immediately serialize it again, a NPE is thrown at: org.drools.core.reteoo.ObjectTypeNode$ExpireJobContextTimerOutputMarshaller.serialize(ObjectTypeNode.java:669). When you deserialize the session and then advance the pseudo clock to a moment where the original event (which we've already retracted from the working memory) should have expired, a NPE is thrown at: org.drools.core.common.AbstractWorkingMemory$WorkingMemoryReteExpireAction.execute(AbstractWorkingMemory.java:1524)
So, it seems that when the Event is explicitly retracted with KieSesion.delete(event), the event is removed from the WM, but the Expiry Timer Job is not. That ExpiryJob gets serialized with a 'null' fact handle, which does not give issues on de-serialization, but on the next serialization of the session, or when an action is peformed that triggers the expire action (i.e. move the pseudo-clock).
A reproducer can be found here: http://www.github.com/DuncanDoyle/DroolsSerializationIssue . To reproduce:
git clone http://www.github.com/DuncanDoyle/DroolsSerializationIssue
mvn clean test -P phreak (runs the test with Drools in PHREAK mode)
mvn clean test -P reteoo (runs the test with Drools in RETEOO mode)
In both modes 2 of the 3 tests produce an NPE.
Fixed by https://github.com/droolsjbpm/drools/commit/ccd415f20
Cherry-picked to 6.0.x with https://github.com/droolsjbpm/drools/commit/7b1331c26
This is to be fixed in 6.0.3. It is the original issue to bug 1130937, which I will close as duplicate.
*** Bug 1130937 has been marked as a duplicate of this bug. ***
Verified with BRMS-6.0.3.ER1