[HDFS-12744] More logs when short-circuit read is failed and disabled

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.9.0, 3.0.0
• Component/s: datanode
• Labels: supportability
• Hadoop Flags: Reviewed
• Assignee: Weiwei Yang
• Reporter: Weiwei Yang
• Created: 30/Oct/17 05:55
• Updated: 02/Nov/17 01:43
• Resolved: 01/Nov/17 09:10

Description

Short-circuit read (SCR) failed with following error

2017-10-21 16:42:28,024 WARN  [B.defaultRpcServer.handler=7,queue=7,port=16020] 
impl.BlockReaderFactory: BlockReaderFactory(xxx): unknown response code ERROR
while attempting to set up short-circuit access. Block xxx is not valid

then short-circuit read is disabled for 10 minutes without any warning message given in the log. This causes us spent some more time to figure out why we had a long time window that SCR was not working. Propose to add a warning log (other places already did) to indicate SCR is disabled and some more logging in DN to display what happened.

Issue Links

• is related to: HDFS-12528 Add an option to not disable short-circuit reads on failures