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https://issues.apache.org/jira/browse/HBASE-17462?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15830789#comment-15830789
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Ted Yu commented on HBASE-17462:
--------------------------------
{code}
+ for (RegionLoad rl : regionLoadList) {
+ double current = getCostFromRl(rl);
+ if (previous != null) {
+ cost += current - previous;
+ }
+ previous = current;
{code}
(Through debug logging) what is length of regionLoadList for the read / write
requests ?
The average length would give us some idea how many samples are taken for the
sliding window.
Can you share (improved) performance when you tested the change on your cluster
?
Thanks
> 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-17642.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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