[HDFS-13594] the lock of ShortCircuitCache is hold while close the ShortCircuitReplica

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.0.2
• Component/s: hdfs-client
• Assignee: Lisheng Sun
• Reporter: Gang Xie
• Created: 18/May/18 10:43
• Updated: 22/Nov/19 01:23

Description

When we are profiling SC read, we find that ShortCircuitCache's lock is a hot spot. After look into the code, we find that when close BlockReaderLocal, it tries to  trimEvictionMaps, and several ShortCircuitReplicas are closed while the lock being hold.  This slows down the close of the BlockReaderLocal, and the worse is that it blocks the other allocating of the new ShortCircuitReplicas. 

An idea to avoid this is to close the replica in an async way. I will do a prototype and get the performance.