When firing an CDI event from another transaction synchronisation, the {{ TransactionalObserverNotifier }} fails to defer the notification, because registering the {{ TransactionSynchronizedRunnable }} fails with an "ARJUNA016082: Synchronizations are not allowed".
In my case this for example happens when I fire the event from a JPA Lifecycle listener, which is triggered by the flush call on the {{ EntityManager }} through Hibernates {{ JtaTransactionCoordinatorImpl }} bound in the {{ JCAOrderedLastSynchronizationList }} .
The current behaviour has one very odd side effect: namely, the exception is swallowed in the {{ TransactionalObserverNotifier }} , which then notifies a filtered set of observers, assuming that a rollback exception must have occurred. As a result, the ` {{ AFTER_FAILURE ` }} observers are invoked and not the ` {{ AFTER_SUCCESS ` }} observers, even though the transaction commits successfully (because the {{ IllegalStateException }} was caused by not being able to register the synchronisation, and not due to the fact that the transaction failed altogether).
I think the error handling should be fixed, because it seems odd that {{ AFTER_FAILURE }} observers get invoked for a successful transaction.
Furthermore it would be nice to actually support events with transactional observers to be fired from another synchronisation. I am not entirely sure whether it is feasible to support, but I am having a couple of ideas:
* an implementation where we just register a synchronisation by default and handle the synchronisation from there, rather than registering the synchronisation on the transaction just in time
* Hook on the {{ JCAOrderedLastSynchronizationList }} instead of the Transaction, just as Hibernate seems to do
* Register an interposed _interposed_ synchronisation with the {{TransactionSynchronizationRegistry}} rather than a regular synchronisation.
Some more background (a stack trace) can be found in the Stackoverflow issue: https://stackoverflow.com/questions/47953827/defer-transactionalobservernotifier-fails-with-arjuna016082-synchronizations-ar
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