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https://issues.apache.org/jira/browse/ACCUMULO-3510?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Josh Elser updated ACCUMULO-3510:
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Fix Version/s: (was: 1.7.0)
1.8.0
> Create mechanism to support priority based scheduling of read ahead tasks.
> ---------------------------------------------------------------------------
>
> Key: ACCUMULO-3510
> URL: https://issues.apache.org/jira/browse/ACCUMULO-3510
> Project: Accumulo
> Issue Type: Improvement
> Components: tserver
> Affects Versions: 1.6.0
> Reporter: marco polo
> Assignee: marco polo
> Priority: Minor
> Fix For: 1.8.0
>
>
> I have many cases where ScanSessions will consume resources that I otherwise
> want shorter running scans to utilize. In some cases, a scan may continue for
> hours, while a short running scan may come in and execute quickly. As a
> result, I want to be able to adjust the priority of these scan sessions.
> I have a patch which is forthcoming, that breaks Session out of TabletServer
> and replaces the queue in the readAheadThreadPool with a priority pool. The
> comparator I have created as a proof of concept, which can be adjustable,
> reduces the priority of the oldest scan. Using an aging technique, we
> guarantee execute of these older running scans based upon the previous run
> time. As a result, we give preference to newer scans. If they execute
> quickly, older scans will have an inherent rise in priority. If they also
> take a while, their priority will be reduced and incoming scans will yet
> again be given a greater priority with the intent (and/or hope ) their
> execution will be faster.
> Priority should be configurable based on the desired Session Comparator.
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