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https://issues.apache.org/jira/browse/HBASE-13965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14615265#comment-14615265
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Ted Yu commented on HBASE-13965:
--------------------------------
{code}
32 public void updateStochasticCost(String tableName, String
costFunctionName,
{code}
Should tableName parameter be of type TableName ?
For MetricsStochasticBalancerSourceImpl.java , it should be annotated with
@InterfaceAudience.Private
{code}
56 * The function that report stochastic load balancer costs to JMX
{code}
'that report' -> 'that reports'
{code}
58 public void updateStochasticCost(String tableName, String
costFunctionName,
59 String costFunctionDesc, Double value) {
{code}
costFunctionDesc isn't used in the method.
{code}
82 String attrName = tableName + ((tableName.length() <= 0) ? ""
: TABLE_FUNCTION_SEP) + key;
{code}
When would tableName.length() be <= 0 ? There is check at the beginning of
updateStochasticCost().
{code}
124 private Double[] lastSubcosts;
{code}
nit: Uppercase 'c' of 'costs'
{code}
470 this.lastSubcosts[i] = multiplier*cost;
471 total += multiplier * cost;
{code}
There is no need to perform the same multiplication twice.
> Stochastic Load Balancer JMX Metrics
> ------------------------------------
>
> Key: HBASE-13965
> URL: https://issues.apache.org/jira/browse/HBASE-13965
> Project: HBase
> Issue Type: Improvement
> Components: Balancer, metrics
> Reporter: Lei Chen
> Assignee: Lei Chen
> Attachments: HBASE-13965-v3.patch, HBASE-13965_v2.patch,
> HBase-13965-v1.patch, stochasticloadbalancerclasses_v2.png
>
>
> Today’s default HBase load balancer (the Stochastic load balancer) is cost
> function based. The cost function weights are tunable but no visibility into
> those cost function results is directly provided.
> A driving example is a cluster we have been tuning which has skewed rack size
> (one rack has half the nodes of the other few racks). We are tuning the
> cluster for uniform response time from all region servers with the ability to
> tolerate a rack failure. Balancing LocalityCost, RegionReplicaRack Cost and
> RegionCountSkew Cost is difficult without a way to attribute each cost
> function’s contribution to overall cost.
> What this jira proposes is to provide visibility via JMX into each cost
> function of the stochastic load balancer, as well as the overall cost of the
> balancing plan.
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