[HBASE-20665] "Already cached block XXX" message should be DEBUG

• Type: Task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.2.0, 2.0.0
• Fix Version/s: 3.0.0-alpha-1, 2.1.0, 1.3.3, 2.0.1, 1.2.7
• Component/s: BlockCache
• Labels: beginner
• Hadoop Flags: Reviewed
• Assignee: Eric Maynard
• Reporter: Sean Busbey
• Created: 31/May/18 17:57
• Updated: 08/Jun/18 13:39
• Resolved: 07/Jun/18 15:45

Description

Testing a local cluster that relies on the LruBlockCache for a scan-heavy workload and I'm getting a bunch of log entries at WARN

2018-05-30 12:28:47,192 WARN org.apache.hadoop.hbase.io.hfile.LruBlockCache: Cached an already cached block: df01f5bf6a244f6bb1a626b927377fff_54780812 cb:df01f5bf6a244f6bb1a626b927377fff_54780812. This is harmless and can happen in rare cases (see HBASE-8547)

As the log message notes (and the code confirms) this is a harmless result of contention for getting a block into the CHM. the message should be at DEBUG.