Description Andrei Ilitchev 2010-06-03 10:17:57 EDT

EntityManagerImpl.unwrap method may begin transaction to unwrap connection:
} else if (cls.equals(java.sql.Connection.class)) {
    UnitOfWorkImpl unitOfWork = (UnitOfWorkImpl) this.getUnitOfWork();
    if (!unitOfWork.isInTransaction()) {
        unitOfWork.beginEarlyTransaction();
        return (T) unitOfWork.getAccessor().getConnection();
    }
}

First of all, if uow's parent is ExclusiveIsolatedClientSession then the connection is alwaya available - no need to beginEarlyTransaction;

Secondly - and most important - in JTA environment with no transaction it will start a JTA transaction. It should be called only inside transaction.

I suggest something like:

} else if (cls.equals(java.sql.Connection.class)) {     
    UnitOfWorkImpl unitOfWork = (UnitOfWorkImpl) this.getUnitOfWork();
    if(unitOfWork.getParent().isExclusiveIsolatedClientSession() {
        return (T) unitOfWork.getAccessor().getConnection();
    }
    if (checkForTransaction(false) != null && !unitOfWork.isInTransaction()) {
        unitOfWork.beginEarlyTransaction();
    }
    if(unitOfWork.isInTransaction()) {
        return (T) unitOfWork.getAccessor().getConnection();
    } else {
        return null;
    }
}