[jira] [Updated] (CASSANDRA-17877) Speculative execution threshold unit mismatch

["Jon Meredith (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-17877?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jon Meredith updated CASSANDRA-17877:
-------------------------------------
     Bug Category: Parent values: Degradation(12984)Level 1 values: Resource Management(12995)
       Complexity: Normal
    Discovered By: User Report
    Fix Version/s: 4.1-beta
         Severity: Normal
           Status: Open  (was: Triage Needed)

> Speculative execution threshold unit mismatch
> ---------------------------------------------
>
>                 Key: CASSANDRA-17877
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-17877
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Consistency/Coordination
>            Reporter: Jon Meredith
>            Assignee: Jon Meredith
>            Priority: Normal
>             Fix For: 4.1-beta
>
>
> CASSANDRA-16760 changed the ColumnFamilyStore.coordinatorRead/WriteLatency to be in microseconds rather than nanoseconds but did not change the calculation for ColumnFamilyStore.sampleReadLatencyNanos/additionalWriteLatency which is used as the threshold for speculative read execution / issuing additional writes.
> The impact of this bug is that the threshold is 1000x smaller than intended when using percentile based speculation (tables default to 99p), so effectively speculation happens for ALL reads configured to speculate on a percentile, including min hybrid policies that use percentiles.



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