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https://issues.apache.org/jira/browse/ACCUMULO-4643?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16045563#comment-16045563
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Ivan Bella commented on ACCUMULO-4643:
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[~kturner] It is interesting in test 1 that the standard deviation is so high.
With 128 threads and 127 scans, I would have expected all of the scans to get a
fair amount of processing time. I am wondering if the max open files is
causing issues there. That might explain why the mean and standard deviations
is lower in test 2 since the files get closed when one scan yields. These
types of results I would expect when the number of tserver threads is smaller
than the number of long running scans and would be exactly what I would want to
see.
I am not sure what to do with test 3. I am guessing there is a test 4 coming
which is comparable to test 3 but with yielding.
> Allow iterators to interrupt themselves
> ---------------------------------------
>
> Key: ACCUMULO-4643
> URL: https://issues.apache.org/jira/browse/ACCUMULO-4643
> Project: Accumulo
> Issue Type: Improvement
> Components: tserver
> Affects Versions: 1.8.1, 2.0.0
> Reporter: Ivan Bella
> Assignee: Ivan Bella
> Labels: features
> Fix For: 2.0.0
>
> Time Spent: 17h 10m
> Remaining Estimate: 0h
>
> The idea here is to allow an iterator stack to send back a special key or
> throw a special exception which will allow the tablet server to tear down the
> scan to be rebuilt later. This is to handle the case where an iterator is
> doing a lot of work without returning results to avoid starving out other
> scans.
> There are two thoughts on how to do this:
> 1) A special "interrupt" key is returned from the getTopKey call that is
> detected in the Tablet.nextBatch call, is not added to the results, but is
> used to add an unfinished range and results in the remaining ranges to be
> deemed unfinished.
> 2) An special exception is thrown from the next or seek call that included
> the key of the current position, and the same actions are taken as in 1).
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