SQLException during JDBC operation in direct Netezza import/export signals parent thread to fail fast by interrupting it (see here).
We're trying to process the interrupt in the parent (main) thread, but there's no guarantee that we're not in some blocking internal call that will process the interrupted flag and reset it before we're able to check.
It is also possible that the parent thread has passed the "checking part" when it gets interrupted. In case of NetezzaExternalTableExportMapper this can interrupt the upload of log files.
I'd recommend using some other means of communication between the threads than interrupts.