This bug originates out of a StackOverflow question pertaining to jena-text
However upon investigation the culprit appears to be DatasetGraphWithLock, reproducing my analysis from my SO answer here:
The issue is that the dataset with inference implicitly uses ARQ's standard in-memory Dataset implementation and this does not support transactions.
However text datasets which correspond to DatasetGraphText internally (and in your stack trace) requires the wrapped dataset to support transactions and where they do not wraps them with DatasetGraphWithLock. It is this that appears to be encountering the problem with the lock, the documentation states that this should support multiple readers but having followed the logic of the code I'm not sure that it actually allows this.
I put together the following test case which illustrates the issue:
So the problem appears to be that DatasetGraphWithLock claims multi-reader support but in reality does not allow this.