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

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

Hoss Man created SOLR-8849:
------------------------------

             Summary: 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


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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