[MAPREDUCE-4274] MapOutputBuffer should use native byte order for kvmeta

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.0-alpha
• Fix Version/s: 2.0.2-alpha
• Component/s: performance, task
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 20/May/12 21:43
• Updated: 16/Mar/15 18:44
• Resolved: 21/May/12 19:07

Description

I don't have a benchmark to support this, but this should give a small CPU improvement on the map output buffer: currently, we create kvmeta as ByteBuffer.wrap(kvbuffer).asIntBuffer(). According to the javadocs, the resulting int buffer will inherit its byte order from the ByteBuffer it comes from, and the byte buffer defaults to BIG_ENDIAN. Thus, all of our int access to/from the buffer will require byte-swapping.