GitHub user kevpeek opened a pull request:
https://github.com/apache/storm/pull/1790
STORM-2210 - remove array shuffle from ShuffleGrouping when counter resets
to zero
This Collection.shuffle is problematic for 2 reasons.
(1) in the existing implementation, the code resets current to zero before
doing the shuffle, which opens a window during which other threads may access
the not-yet-reshuffled array (or the mid-shuffle array).
(2) If we call Collection.shuffle() before resetting current to zero, there
is still a chance that some other thread is being slow and trying to access one
of the upper indexes. E.g. choices.get(size - 3). Shuffling the array first
could cause this thread to get the post-shuffle value instead of the
pre-shuffle value.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/kevpeek/storm STORM-2210
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/storm/pull/1790.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 #1790
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commit 980af8083aaf185fad3db476dd765abe4ea9cda4
Author: Kevin Peek <kp...@salesforce.com>
Date: 2016-11-21T18:53:33Z
remove array shuffle from ShuffleGrouping when counter resets to zero
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