[MAPREDUCE-1059] distcp can generate uneven map task assignments

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Component/s: distcp
• Hadoop Flags: Reviewed
• Assignee: Aaron Kimball
• Reporter: Aaron Kimball
• Created: 05/Oct/09 23:46
• Updated: 05/Jan/10 15:58
• Resolved: 23/Dec/09 10:17

Description

distcp writes out a SequenceFile containing the source files to transfer, and their sizes. Map tasks are created over spans of this file, representing files which each mapper should transfer. In practice, some transfer loads yield many empty map tasks and a few tasks perform the bulk of the work.