[HADOOP-1440] JobClient should not sort input-splits

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.12.3
• Fix Version/s: 0.14.0

Environment

All

• Assignee: Senthil Subramanian
• Reporter: Milind Barve
• Created: 29/May/07 23:00
• Updated: 11/Feb/10 18:03
• Resolved: 20/Jun/07 21:14

Description

Currently, the JobClient sorts the InputSplits returned by InputFormat in descending order, so that the map tasks corresponding to larger input-splits are scheduled first for execution than smaller ones. However, this causes problems in applications that produce data-sets partitioned similarly to the input partition with -reducer NONE.

With -reducer NONE, map task i produces part-i. Howver, in the typical applications that use -reducer NONE it should produce a partition that has the same index as the input parrtition.

(Of course, this requires that each partition should be fed in its entirety to a map, rather than splitting it into blocks, but that is a separate issue.)

Thus, sorting input splits should be either controllable via a configuration variable, or the FileInputFormat should sort the splits and JobClient should honor the order of splits.

Issue Links

• relates to: HADOOP-1320 Rewrite 'random-writer' to use '-reducer NONE'