[MAPREDUCE-6009] Map-only job with new-api runs wrong OutputCommitter when cleanup scheduled in a reduce slot

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.2.1
• Fix Version/s: 1.3.0, 1.2.2
• Component/s: client, job submission
• Assignee: Gera Shegalov
• Reporter: Gera Shegalov
• Created: 28/Jul/14 06:58
• Updated: 23/Jul/15 07:42
• Resolved: 21/Oct/14 15:20

Description

In branch 1 job commit is executed in a JOB_CLEANUP task that may run in either map or reduce slot

in org.apache.hadoop.mapreduce.Job#setUseNewAPI there is a logic setting new-api flag only for reduce-ful jobs.

    if (numReduces != 0) {
      conf.setBooleanIfUnset("mapred.reducer.new-api",
                             conf.get(oldReduceClass) == null);
      ...

Therefore, when cleanup runs in a reduce slot, ReduceTask inits using the old API and runs incorrect default OutputCommitter, instead of consulting OutputFormat.