Currently mapreduce.task.userlog.limit.kb controls both the length of task attempt logs and MA-AM attempt logs. Obviously, MR-AM log is not userlog.
We are interested in keeping MR-AM log either in its entirety or in much larger size than task logs for debugging.
MAPREDUCE-5672 introduced CRLA. We already use a dedicated setting for how many backups of rolled files we keep for MR-AM. However, for large jobs with tens of megabyte AM log, it means that you have a long series of files. A natural improvement is to have a configuration yarn.app.mapreduce.am.container.log.limit.kb . It allows to either disable rolling the log for altogether while keeping it for the task attempts, or to use much a larger limit to make rolling less frequent.