In case it's useful I've found how to enable bit more debug logging on the jobmanager:
flink_jobmanager_log.txt <http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/file/t1147/flink_jobmanager_log.txt> -- Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/
