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https://issues.apache.org/jira/browse/HBASE-17462?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15830861#comment-15830861
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Tim Brown edited comment on HBASE-17462 at 1/20/17 12:05 AM:
-------------------------------------------------------------

The regionLoadList has a configurable size. By default it is 15 and controlled 
by "hbase.master.balancer.stochastic.numRegionLoadsToRemember".

For performance, I can attach some screenshots of charts that look at the 
average number of requests per region server. If you want more in depth 
analysis let me know.


was (Author: timbrown):
The regionLoadList has a configurable size. By default it is 15 and controlled 
by `hbase.master.balancer.stochastic.numRegionLoadsToRemember`.

For performance, I can attach some screenshots of charts that look at the 
average number of requests per region server. If you want more in depth 
analysis let me know.

> Investigate using sliding window for read/write request costs in 
> StochasticLoadBalancer
> ---------------------------------------------------------------------------------------
>
>                 Key: HBASE-17462
>                 URL: https://issues.apache.org/jira/browse/HBASE-17462
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Ted Yu
>            Assignee: Tim Brown
>              Labels: patch
>         Attachments: HBASE-17462.patch
>
>
> 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.



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