MAPREDUCE-6958 added the content length to ShuffleHandler audit log, which is logged at DEBUG level. After enabling it, we found that the list of mappers for large jobs was filling up our audit logs. It would be good to move the list of mappers to TRACE level to reduce the logging impact without disabling the log message entirely.
For example a log message like this:
Would become this with log4j.logger.org.apache.hadoop.mapred.ShuffleHandler.audit=DEBUG:
And this with log4j.logger.org.apache.hadoop.mapred.ShuffleHandler.audit=TRACE:
One question is whether there are any downstream consumers of this audit log that might have a problem with this change?