[Hadoop-common-dev] [jira] [Reopened] (HADOOP-6918) Make metrics naming consistent

Make metrics naming consistent
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Key: HADOOP-6918
URL: https://issues.apache.org/jira/browse/HADOOP-6918
Project: Hadoop Common
Issue Type: Improvement
Components: metrics
Affects Versions: 0.20.2
Reporter: Luke Lu
Assignee: Luke Lu
Fix For: 0.23.0


While working HADOOP-6728, I noticed that our metrics naming style is all over the place:
* Capitalized camel case: e.g., "FilesCreated" in namenode metrics and some rpc metrics
* uncapitalized camel case: e.g, "threadsBlocked" in jvm metrics and some rpc metrics
* lowercased underscored: e.g., "bytes_written" in datanode metrics and mapreduce metrics
Let's make them consistent. How about uncapitalized camel case? My main reason for the camel case: some backends have limits on the name length and underscore is wasteful.
Once we have a consistent naming style we can do:
@Metric("Number of INodes created") MutableCounterLong filesCreated;
instead of the more redundant:
@Metric({"FilesCreated", "Number of INodes created"}) MutableCounterLong filesCreated;