[HDFS-15307] Update description of "dfs.client.socketcache.*" properties to not have mention of short-circuits

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.1.3
• Component/s: caching, dfsclient

Environment

Hadoop 3.1.3

• Assignee: Unassigned
• Reporter: Andrey Elenskiy
• Created: 28/Apr/20 23:14
• Updated: 28/Apr/20 23:14

Description

Both `dfs.client.socketcache.capacity` and `dfs.client.socketcache.expiryMsec` mention that cache is for short-circuit reads. That appears to be not the case as PeerCache is also used for caching TCP remote connections:

https://github.com/apache/hadoop/blob/3f223bebfa6b382a762edcc518fcbae310ce22e5/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/impl/BlockReaderRemote.java#L312

https://github.com/apache/hadoop/blob/3f223bebfa6b382a762edcc518fcbae310ce22e5/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/impl/BlockReaderFactory.java#L815