[HBASE-25998] Revisit synchronization in SyncFuture

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha-1, 1.7.0, 2.5.0
• Fix Version/s: 3.0.0-alpha-1, 2.5.0, 2.3.6, 2.4.5
• Component/s: Performance, regionserver, wal
• Assignee: Bharath Vissapragada
• Reporter: Bharath Vissapragada
• Created: 11/Jun/21 15:51
• Updated: 20/Jun/21 02:34
• Resolved: 19/Jun/21 00:52

Description

While working on HBASE-25984, I noticed some weird frames in the flame graphs around monitor entry exit consuming a lot of CPU cycles (see attached images). Noticed that the synchronization there is too coarse grained and sometimes unnecessary. I did a simple patch that switched to a reentrant lock based synchronization with condition variable rather than a busy wait and that showed 70-80% increased throughput in WAL PE. Seems too good to be true.. (more details in the comments).

Issue Links

• links to: GitHub Pull Request #3382
• links to: GitHub Pull Request #3399
• links to: GitHub Pull Request #3400
• links to: GitHub Pull Request #3401