[HDFS-8813] Erasure Coding: Client no need to decode missing parity blocks

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: HDFS-7285
• Hadoop Flags: Reviewed
• Assignee: Walter Su
• Reporter: Walter Su
• Created: 23/Jul/15 12:25
• Updated: 30/Sep/15 19:37
• Resolved: 23/Jul/15 18:42

Description

Assume 6+3 schema.
Assume data block #2 is missing, then InputStream tries to read parity block #6.
Assume parity block #6 is missing too. And InputStream successfully reads parity block #7.
Then begin to decode.

Currently InputStream will decode #2 and #6. But client(user) only need #2. The parity block #6 will be disposed.

The improvement is we only decode #2.