[jira] [Resolved] (SOLR-8849) ChaosMonkey should cuase chaos in a more reproducible manner

["Hoss Man (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SOLR-8849?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hoss Man resolved SOLR-8849.
----------------------------
       Resolution: Fixed
    Fix Version/s: 6.0
                   master

> ChaosMonkey should cuase chaos in a more reproducible manner
> ------------------------------------------------------------
>
>                 Key: SOLR-8849
>                 URL: https://issues.apache.org/jira/browse/SOLR-8849
>             Project: Solr
>          Issue Type: Test
>            Reporter: Hoss Man
>            Assignee: Hoss Man
>             Fix For: master, 6.0
>
>         Attachments: SOLR-8849.patch
>
>
> Looking into the ChaosMonkey code a bit, and it seems like this class -- particularly the way {{monkeyThread}} is defined -- uses randomness in a way that makes it extremely unlikely that it will ever create reproducible failures.
> Obviously in any test where there are multiple concurrent threads, timing issues might prevent test reproducibility -- but in this case, even the sequence of "chaos" actions the monkeyThread takes won't be reproducible if anyother concurrent test thread accesses {{LuceneTestCase.random()}} ...
> {code}
>       public void run() {
>         while (!stop) {
>           try {
>     
>             Random random = LuceneTestCase.random();
>             // ... lots of stuff using random, or calling methods that use LuceneTestCase.random() directly
> {code}
> It seems like it would be a lot better if ChaosMonkey's constructor created it's own private {{Random chaosRand}} using {{LuceneTestCase.random()}} as a seed, and then used {{chaosRand}} to make all random choices in it's methods.
> That way at least the sequence of chaotic operations made by ChaosMonkey would be consistent for a given test seed, even if the exact timing/interleaving of those operations relative to other operations by other threads couldn't be garunteed.



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