I have a query that I want to execute from multiple threads using statefulKnowledgeSession.getQueryResults. One of the threads wants to invoke lock.writeLock().lock() in the 105th line of UpgradableReentrantReadWriteLock. The problem is that the other threads already own the readLock and they cannot proceed until the first query thread finishes with its job. They will wait for each other.
I experienced the same problem with 5.4.0.Final as well.