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Posted to commits@cassandra.apache.org by "Gianluca Righetto (Jira)" <ji...@apache.org> on 2020/06/01 15:55:00 UTC

[jira] [Commented] (CASSANDRA-15792) test_speculative_data_request - read_repair_test.TestSpeculativeReadRepair

    [ https://issues.apache.org/jira/browse/CASSANDRA-15792?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17121116#comment-17121116 ] 

Gianluca Righetto commented on CASSANDRA-15792:
-----------------------------------------------

[~jmckenzie] After investigating this for some time now, I determined this is mostly related to a low write timeout used in TestSpeculativeReadRepair. That may lead to a speculated write to a different node depending on how long the original node takes to apply the repair mutation, but the test assertion is expecting no speculated writes. In other words, this is mostly a problem with the test, not with C* runtime, which is doing the right thing.

In order to fix this, I made it accept speculated writes in the original test, but I also replicated the test method in a different test class with a longer write timeout to reduce the likelihood of speculated writes. Of course, since this is all time based, the new test may still fail under a system with high CPU contention, but at least for now I can't easily reproduce the failure anymore (whereas it was failing consistently for me before).

Here's the pull request in my cassandra-dtest fork: [https://github.com/grighetto/cassandra-dtest/pull/1]

Regarding the fixver, I'm ok with moving this to beta, even though the fix is already available, it still needs to go through review, but since this is not a runtime problem, I wouldn't say this is a blocker for alpha.

> test_speculative_data_request - read_repair_test.TestSpeculativeReadRepair
> --------------------------------------------------------------------------
>
>                 Key: CASSANDRA-15792
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-15792
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Test/dtest
>            Reporter: Ekaterina Dimitrova
>            Assignee: Gianluca Righetto
>            Priority: Normal
>             Fix For: 4.0-alpha
>
>
> Failing on the latest trunk here:
> https://app.circleci.com/pipelines/github/ekaterinadimitrova2/cassandra/127/workflows/dfba669d-4a5c-4553-b6a2-85647d0d8d2b/jobs/668/tests
> Failing once in 30 times as per Jenkins:
> https://jenkins-cm4.apache.org/job/Cassandra-trunk-dtest/69/testReport/dtest.read_repair_test/TestSpeculativeReadRepair/test_speculative_data_request/



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