GitHub user JoshRosen opened a pull request:
https://github.com/apache/spark/pull/16340
[SPARK-18928] Check TaskContext.isInterrupted() in FileScanRDD, JDBCRDD &
UnsafeSorter
## What changes were proposed in this pull request?
In order to respond to task cancellation, Spark tasks must periodically
check `TaskContext.isInterrupted()`, but this check is missing on a few
critical read paths used in Spark SQL, including `FileScanRDD`, `JDBCRDD`, and
UnsafeSorter-based sorts. This can cause interrupted / cancelled tasks to
continue running and become zombies (as also described in #16189).
This patch aims to fix this problem by adding `TaskContext.isInterrupted()`
checks to these paths. Note that I could have used `InterruptibleIterator` to
simply wrap a bunch of iterators but in some cases this would have an adverse
performance penalty or might not be effective due to certain special uses of
Iterators in Spark SQL. Instead, I inlined `InterruptibleIterator`-style logic
into existing iterator subclasses.
## How was this patch tested?
Tested manually in `spark-shell` with two different reproductions of
non-cancellable tasks, one involving scans of huge files and another involving
sort-merge joins that spill to disk. Both causes of zombie tasks are fixed by
the changes added here.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/JoshRosen/spark sql-task-interruption
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16340.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 #16340
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commit 08f9aa5a1dde58cf45f75b67ee88a9b978c3486c
Author: Josh Rosen <[email protected]>
Date: 2016-12-19T19:27:26Z
Fix FileScanRDD interruption.
commit 2d43d5a501a162384d45eedf188ffed178e96351
Author: Josh Rosen <[email protected]>
Date: 2016-12-19T19:28:40Z
Fix for JDBCRDD interruption.
commit 236efe580b52ed7ec6ce9e36f9b814147ebad99d
Author: Josh Rosen <[email protected]>
Date: 2016-12-19T21:22:07Z
Make UnsafeSorterIterator interruptible.
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