[jira] [Commented] (ACCUMULO-2608) Create a randomwalk replay meta-node

["Keith Turner (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-2608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13971674#comment-13971674 ] 

Keith Turner commented on ACCUMULO-2608:
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Some things to consider :

 * Test nodes make random decisions.  For example the shard Insert nodes generates random documents.  So even if you visited notes in the Shard test in the same order, completely different things could happen because different data was generated.  This could possibly be addressed by using the same PRNG and seeding it the same. 
 * Concurrent walkers will generate multiple trails/paths.  Replaying those trail concurrently will very likely not result in the same sequence of events globally.  
 * The XML file the ticket mentions generating and XML file.  This may not fit in memory.

 In my experience when I rerun random walk I usually see the same bugs.  If I only see a bug once over weeks of running random walk on 20 nodes, it indicates that the bug may be improbable and therefore of a lower priority.  There are certainly a few bugs that I only ever saw once in random walk and could not figure them and never saw them again.  I saw these on a cluster w/ many walkers.

> Create a randomwalk replay meta-node
> ------------------------------------
>
>                 Key: ACCUMULO-2608
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2608
>             Project: Accumulo
>          Issue Type: New Feature
>          Components: test
>            Reporter: Mike Drob
>            Assignee: Bill Havanki
>            Priority: Critical
>             Fix For: 1.4.6, 1.5.2, 1.6.1
>
>
> It would be useful to have the ability to replay randomwalk sequences.
> If a randomwalk fails, it is often difficult to reproduce due to the random nature of things. If current test runs were modified to output a specially crafted module representing their sequence, then future runs could accept it as the module to run and improve reproduction capabilities.



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