Details
Description
HBase 0.96's refactored jmx beans do not contain the master's list of dead region servers and live regionservers with load info. HBase 0.94 did (though in a single monolithic blob).
This JMX interface should be considered as much of an API as the the normal wire or java api. Dropping values from this was done without deprecation and the removal of this information is a functional regression.
We should provide the information in the 0.96+ JMX. HBase 0.94 had a monolithic JMX blob ("hadoop:service=Master,name=Master") that contained a lot of information, including the regionserver list and the cached regionserver load for each region found on the master webpage. 0.96+ refactored jmx this into several jmx beans which could be selectively retrieved. These include:
- hadoop:service=HBase,name=Master,sub=AssignmentManager
- hadoop:service=HBase,name=Master,sub=Balancer
- hadoop:service=HBase,name=Master,sub=Server
- hadoop:service=HBase,name=Master,sub=FileSystem
Specifically the (Hadoop:service=HBase,name=Master,sub=Server) listing that used to contain regionservers and deadregionservers in jmx were replaced in with numRegionServers and numDeadRegionservers which only contain counts.
I propose just adding another mbean called "RegionServers" under the bean: "hadoop:service=HBase,name=Master,sub=RegionServers"