[HBASE-25642] Fix or stop warning about already cached block

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.0
• Fix Version/s: 2.5.0, 3.0.0-alpha-2, 2.4.6, 2.3.7
• Component/s: BlockCache, Operability, regionserver
• Hadoop Flags: Reviewed
• Assignee: Andrew Kyle Purtell
• Reporter: Nick Dimiduk
• Created: 05/Mar/21 22:37
• Updated: 01/Sep/21 19:01
• Resolved: 31/Aug/21 16:28

Description

Our logs have as a fairly common occurrence:

2021-03-05 22:24:31,034 WARN  [StoreFileOpener-foo-1] hfile.BlockCacheUtil: Caching an already cached block: blah.bub. This is harmless and can happen in rare cases (see HBASE-8547)

If this is really harmless, why do we log? If it's not actually harmless, let's take another pass at fixing this situation.

Issue Links

• is related to: HBASE-8547 Fix java.lang.RuntimeException: Cached an already cached block
• links to: GitHub Pull Request #3638