[jira] [Created] (IMPALA-8179) Backend tests are flaky: time-based srand

["Jim Apple (JIRA)" <ji...@apache.org>]

Jim Apple created IMPALA-8179:
---------------------------------

             Summary: Backend tests are flaky: time-based srand
                 Key: IMPALA-8179
                 URL: https://issues.apache.org/jira/browse/IMPALA-8179
             Project: IMPALA
          Issue Type: Bug
          Components: Backend
    Affects Versions: Impala 3.2.0
            Reporter: Jim Apple
            Assignee: Joe McDonnell


https://gerrit.cloudera.org/#/c/12124/9/be/src/service/unified-betest-main.cc added

{noformat}
    uint32_t seed = time(NULL);
    cout << "seed = " << seed << endl;
    srand(seed);
{noformat}

There is no way to force the seed, and backend tests using {{rand()}} are then flaky by default. We should make them unflaky by default (using a specific random seed) and we should also provide a way to override this by setting it by time or to a specific seed for just one run, to help with debugging.

If we want the coverage that comes from running with a different seed each time, we could run a test multiple times.



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