Major Description
In the thread, http://search-hadoop.com/m/HBase/YGbbyUZKXWALkX1, Timothy was asking whether the read/write request costs in StochasticLoadBalancer should be calculated as rates.
This makes sense since read / write load on region server tends to fluctuate over time. Using sliding window would reflect more recent trend in read / write load.
Some factors to consider:
The data structure used by StochasticLoadBalancer should be concise. The
number of regions in a cluster can be expected to approach 1 million. We
cannot afford to store long history of read / write requests in master.
Efficiency of cost calculation should be high - there're many cost
functions the balancer goes through, it is expected for each cost function
to return quickly. Otherwise we would not come up with proper region
movement plan(s) in time.
