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From "Christopher Batey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-12585) Fixup Cassandra Stress reporting thread model and precision
Date Mon, 05 Sep 2016 14:08:20 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-12585?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15465090#comment-15465090
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Christopher Batey commented on CASSANDRA-12585:
-----------------------------------------------

I'll aim to review this week unless you get to it first [~tjake]

> Fixup Cassandra Stress reporting thread model and precision
> -----------------------------------------------------------
>
>                 Key: CASSANDRA-12585
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12585
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Tools
>            Reporter: Nitsan Wakart
>            Assignee: Nitsan Wakart
>            Priority: Minor
>              Labels: stress
>
> Stress current reporting thread currently has a complex, slow and imprecise method of
collecting measurements from the Consumer threads.
> StressMetrics thread iterates through the Timers (one Timer per op per Consumer thread),
blocks until the consumer thread collects a measurement on that operation, which forces the
consumer thread to collect a report and unblock the StressMetrics thread. This means:
> - Reporting intervals are effected by sleep interval accuracy on the StressMetrics thread
> - Interval report timing is staggered as the operations get collected.
> - The intended logging interval often does not resemble the effective interval.
> This patch simplifies collection method and resolves the above issues:
> - Each Consumer thread submits timing data to a queue
> - StressMetrics thread reads from the queues and merges the data into a report
> - StressMetrics reads and reports for the intended interval, so not effected by timing
inaccuracies
> - Measurement intervals are aligned to the second, improving the ease of measurements
correlation from several nodes.
> See branch here:
> https://github.com/nitsanw/cassandra/tree/fix-reporting-sync-issues



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