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https://issues.apache.org/jira/browse/HBASE-20914?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack updated HBASE-20914:
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Attachment: Screen Shot 2018-07-19 at 1.20.23 PM.png
> Trim Master memory usage
> ------------------------
>
> Key: HBASE-20914
> URL: https://issues.apache.org/jira/browse/HBASE-20914
> Project: HBase
> Issue Type: Sub-task
> Components: master
> Reporter: stack
> Assignee: stack
> Priority: Major
> Fix For: 2.0.2
>
> Attachments: Screen Shot 2018-07-19 at 1.20.23 PM.png, Screen Shot
> 2018-07-19 at 1.20.23 PM.png, Screen Shot 2018-07-19 at 1.38.56 PM.png,
> Screen Shot 2018-07-19 at 1.38.56 PM.png, Screen Shot 2018-07-19 at 2.22.42
> PM.png, Screen Shot 2018-07-19 at 2.43.42 PM.png
>
>
> While working on the parent issue, looking at a heap from a Master tha was
> running ~650 servers and > 300k regions, I tripped over some silly items in
> the heap:
> 1. Balancer has a regions x server matrix which takes up 18% of the Master
> heap according to jxray and 40% according to eclipse. Looks like the matrix
> should be regions x racks which would be much smaller (Issue came in with
> HBASE-18164 Fast locality computation in balancer -Added new
> LocalityCostFunction and LocalityCandidateGenerator ..). See !Screen Shot
> 2018-07-19 at 2.22.42 PM.png! and !Screen Shot 2018-07-19 at 2.43.42
> PM.png!
> 2. Duplicate Strings make up ~5% of the Master heap. Of these, ServerName
> seems to be the font. Interesting is report that there 54k instances of
> ServerName in this heap though there are only 650 Servers. See !Screen Shot
> 2018-07-19 at 1.38.56 PM.png!
> 3. ArrayDequeue initializes its internal elements array with 16 elements. We
> use this in a few places. In Procedures, of which there are many in this
> heap, we near never make use of this array. See !Screen Shot 2018-07-19 at
> 1.20.23 PM.png!
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