[MAPREDUCE-5705] mapreduce.task.io.sort.mb hardcoded cap at 2047

• Type: Bug
• Status: Reopened
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.2.0

Environment

Multinode Dell XD720 cluster Centos6 running HDP2

• Assignee: Unassigned
• Reporter: Joseph Niemiec
• Created: 03/Jan/14 17:58
• Updated: 04/Apr/16 22:52

Description

mapreduce.task.io.sort.mb is hardcoded to not allow values larger then 2047. If you enter a value larger then this the map tasks will always crash at this line -

https://github.com/apache/hadoop-mapreduce/blob/HDFS-641/src/java/org/apache/hadoop/mapred/MapTask.java?source=cc#L746

The nodes at dev site have over 380 GB of Ram each, we are not able to make the best use of large mappers (15GB mappers) because of the hardcoded buffer max. Is there a reason this value has been hardcoded?

–
Also validated on my dev VM. Indeed setting io.sort.mb to 2047 works but 2048 fails.

Issue Links

• duplicates: MAPREDUCE-2308 Sort buffer size (io.sort.mb) is limited to < 2 GB