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From "Christopher Tubbs (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ACCUMULO-3983) Create tablet locator test suite
Date Tue, 01 Sep 2015 19:56:46 GMT

     [ https://issues.apache.org/jira/browse/ACCUMULO-3983?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Christopher Tubbs updated ACCUMULO-3983:
----------------------------------------
    Fix Version/s: 1.8.0

> Create tablet locator test suite
> --------------------------------
>
>                 Key: ACCUMULO-3983
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3983
>             Project: Accumulo
>          Issue Type: Improvement
>            Reporter: Keith Turner
>             Fix For: 1.8.0
>
>
> Looking at ACCUMULO-3982 made me take a look at the tablet locator source code.  When
I was looking at the code, I thought it would be nice if there were more parallelism in doing
metadata lookups (there is a write lock for updating the cache).  However this can be tricky
because if 100 threads need the same info thats not in the cache we do not want to lookup
that information 100 times in metadata.  This made me think we probably need a test for the
locator that measures certain things under different circumstances.
> For example we probably want to measure the following things :
>   * Total cache memory usage
>   * Number of lookups made to the metadata table
>   * Response time of cache
> Would want to run at least the following scenarios when measuring the above.
>   * N threads lookup N different tablet locations against empty cache and populate cache
>   * N threads lookup 1 tablet location against empty cache and populated cache
>   * N threads invalidate N key extents and request location
>   * N threads invalidate 1 key extents and request location
> More scenarios would be needed. 
> Ideally an implementation of tablet locator would minimize the time it takes a thread
to get a response and it would minimize the number of metadata table request.  Hopefully having
this test suite could drive better implementations.  Need to be careful that the test scenarios
are realistic.  
> Would probably want to make the test suite capable of running on multiple machines in-order
to properly simulate sharing the metadata table.



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