[HDFS-14822] [SBN read] Revisit GlobalStateIdContext locking when getting server state id

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.10.0, 3.3.0, 3.1.4, 3.2.2
• Component/s: hdfs
• Labels: release-blocker
• Target Version/s: 2.10.0
• Assignee: Chen Liang
• Reporter: Chen Liang
• Created: 04/Sep/19 18:09
• Updated: 02/Oct/19 17:14
• Resolved: 19/Sep/19 00:25

Description

As mentioned under HDFS-14277. One potential performance issue of Observer read is that GlobalStateIdContext#getLastSeenStateId calls getCorrectLastAppliedOrWrittenTxId which ends up acquiring lock on txnid. We internally had some discussion and analysis, we believe this lock can be avoided, by calling the non-locking version method getLastAppliedOrWrittenTxId.

Issue Links

• is related to: HDFS-14277 [SBN read] Observer benchmark results