GitHub user ryan-williams opened a pull request:

    https://github.com/apache/spark/pull/3524

    fix spillable memory acquisition request

    comment says we should request enough memory to potentially double our
    memory-pool footprint, but the code was actually requesting more than
    that:
    
        currentMemory >= myMemoryThreshold (L66) implies
        2*currentMemory - myMemoryThreshold >= currentMemory
    
    (strict inequality in the former implies it in the latter, as well). We
    were effectively trying to bump our memory footprint to:
    
        3*currentMemory - myMemoryThreshold
    
    I’m assuming that the comment reflects the true intent, not that it was
    mistaken and we actually want (3*cM - mMT).

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/ryan-williams/spark spills

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/spark/pull/3524.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #3524
    
----
commit b5d8ec93c4ad222bdc8cea84e69ff513948a307e
Author: Ryan Williams <ryan.blake.willi...@gmail.com>
Date:   2014-11-13T06:55:02Z

    fix spillable memory acquisition request
    
    comment says we should request enough memory to potentially double our
    memory-pool footprint, but the code was actually requesting more than
    that:
    
        currentMemory >= myMemoryThreshold (L66) implies
        2*currentMemory - myMemoryThreshold >= currentMemory
    
    (strict inequality in the former implies it in the latter, as well). We
    were effectively trying to bump our memory footprint to:
    
        3*currentMemory - myMemoryThreshold
    
    I’m assuming that the comment reflects the true intent, not that it was
    mistaken and we actually want (3*cM - mMT).

----


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