Details
Critical Description
Currently, the metrics for hbase-client are tailored for reporting via a client-side JMX server.
The MetricsConnection handles the metrics management and reporting via the metrics platform from codahale.
This approach worked well for hbase-1.3.1 when the metrics platform was still relatively young, but it could be improved by using the new hbase-metrics-api.
Now that we have an actual hbase-metrics-api that master, regionserver, zookeeper, and other daemons use, it would be good to also allow the client to leverage the metrics-api.
Then, the client could also report its metrics via Hadoop's metrics2 if desired or through another platform that utilizes the hbase-metrics-api.
If left alone, client metrics will continue to be only barely visible through a client-side JMX server.
The migration to the new metrics-api could be done by simply changing the Metrics data types from codahale types to hbase-metrics types without changing the metrics signatures of MetricsConnection unless completely necessary.
The codahale MetricsRegistry would also have to be exchanged for a hbase-metrics MetricsRegistry.
I found this to be a necessary change after attempting to implement my own Reporter to use within the MetricsConnection class.
I was attempting to create a HadoopMetrics2Reporter that extends the codahale ScheduledReporter and reports the MetricsConnection metrics to Hadoop's metrics2 system.
The already existing infrastructure in the hbase-metrics and hbase-metrics-api projects could be easily leveraged for a cleaner solution.
If completed successfully, users could instead access their client-side metrics through the hbase-metrics-api.
