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https://issues.apache.org/jira/browse/HBASE-21256?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16641640#comment-16641640
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Duo Zhang commented on HBASE-21256:
-----------------------------------

Overall LGTM. The only concerns is about the AtomicLong in Random64.

> Improve IntegrationTestBigLinkedList for testing huge data
> ----------------------------------------------------------
>
>                 Key: HBASE-21256
>                 URL: https://issues.apache.org/jira/browse/HBASE-21256
>             Project: HBase
>          Issue Type: Improvement
>          Components: integration tests
>    Affects Versions: 3.0.0
>            Reporter: Zephyr Guo
>            Assignee: Zephyr Guo
>            Priority: Major
>             Fix For: 3.0.0
>
>         Attachments: HBASE-21256-v1.patch, HBASE-21256-v2.patch, 
> HBASE-21256-v3.patch, HBASE-21256-v4.patch, ITBLL-1.png, ITBLL-2.png
>
>
> Recently, I use ITBLL to test some features in our company. I have 
> encountered the following problems:
>   
>  1. Generator is too slow at the generating stage, the root cause is 
> SecureRandom. There is a global lock in SecureRandom( See the following 
> picture). I use Random instead of SecureRandom, and it could speed up this 
> stage(500% up with 20 mapper).  SecureRandom was brought by HBASE-13382, but 
> speaking of generating random bytes, in my opnion,
>  it is the same with Random.
> !ITBLL-1.png!
> 2. VerifyReducer have a cpu cost of 14% on format method. This is cause by 
> create keyString variable. However, keyString may never be used if test 
> result is correct.(and that's in most cases). Just delay creating keyString 
> can yield huge performance boost in verifing stage.
> !ITBLL-2.png!
> 3.Arguments check is needed, because there's constraint between arguments. If 
> we broken this constraint, we can not get a correct circular list.  
>   
>  4.Let big family value size could be configured.
>  
> 5.Avoid starting RS at backup master



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