I went through the config values as per the defaults XML file (still
going through it again now based on what is actually in the code, i.e.
those not in defaults). Here is what I found:
hbase.master.balancer.period - Only used in hbase-default.xml?
hbase.regions.percheckin, hbase.regions.slop - Some tests still have
it but not used anywhere else
zookeeper.pause, zookeeper.retries - Never used? Only in hbase-defaults.xml
And then there are differences between hardcoded and XML based defaults:
hbase.client.pause - XML: 1000, hardcoded: 2000 (HBaseClient) and 30 *
hbase.client.retries.number - XML: 10, hardcoded 5 (HBaseAdmin) and 2 (HMaster)
hbase.hstore.blockingStoreFiles - XML: 7, hardcoded: -1
hbase.hstore.compactionThreshold - XML: 3, hardcoded: 2
hbase.regionserver.global.memstore.lowerLimit - XML: 0.35, hardcoded: 0.25
hbase.regionserver.handler.count - XML: 25, hardcoded: 10
hbase.regionserver.msginterval - XML: 3000, hardcoded: 1000
hbase.rest.port - XML: 8080, hardcoded: 9090
hfile.block.cache.size - XML: 0.2, hardcoded: 0.0
Finally, some keys are already in HConstants, some are in local
classes and others used as literals. There is an issue open to fix
this though. Just saying.