[HDFS-13936] multipart upload to HDFS to support 0 byte upload

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.0
• Fix Version/s: 3.2.0
• Component/s: fs, hdfs
• Target Version/s: 3.3.0
• Assignee: Ewan Higgs
• Reporter: Steve Loughran
• Created: 24/Sep/18 12:35
• Updated: 09/Oct/18 15:14
• Resolved: 09/Oct/18 15:14

Description

MPUs to HDFS fail as you can't concat an empty block. 

Whatever uploads to HDFS needs to recognise that specific case "0-byte file" and rather than try and concat things, just create a 0-byte file there.

Without this, you can't use MPU as a replacement for distcp or alternative commit protocols.