This is the first installment of the promised post-hiera-conversion cleanups:
Olaf Flebbe has updated the mapred-site.xml template to mapred2 and I have cleaned up the variable names. They should all nicely reflect the setting they apply to and have lost their now redundant hadoop_ and hadoop_config_ prefixes.
All the values should have stayed the same. We noticed however that some of those values differ from the Hadoop defaults and are unsure if they still make sense for mapred 2. In our environment we've tuned them quite differently. So a review of those values might be advised, perhaps as a follow-up Jira.