[HBASE-26658] AsyncFSWAL.unackedAppends should clear after transfered to AsyncFSWAL.toWriteAppends

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 3.0.0-alpha-2, 2.4.9
• Component/s: wal
• Assignee: chenglei
• Reporter: chenglei
• Created: 11/Jan/22 11:47
• Updated: 18/Mar/22 15:24
• Resolved: 17/Jan/22 13:21

Description

When ASyncFSWAL syncing to HDFS failed, AsyncFSWAL.unackedAppends are transfered to AsyncFSWAL.toWriteAppends to avoid data loss, but AsyncFSWAL.unackedAppends itself is not cleared. I think there is no need to continue retain them in AsyncFSWAL.unackedAppends because we would open a new HDFS pipeline to resend the AsyncFSWAL.unackedAppends.
BTW : It would also simplify the logic for fixing HBASE-25905, current fix for HBASE-25905 is somewhat hard to understand. I think the problem to cause HBASE-25905 is that AsyncFSWAL.unackedAppends could not exactly reflect the unacked for current HDFS pipeline. If we clear AsyncFSWAL.unackedAppends after transferring them to AsyncFSWAL.toWriteAppends, HBASE-25905 could also avoid.

Issue Links

• relates to: HBASE-25905 Shutdown of WAL stuck at waitForSafePoint
• links to: GitHub Pull Request #4023