GitHub user ericl opened a pull request:
https://github.com/apache/spark/pull/14932
[SPARK-17371] Resubmitted shuffle outputs can get deleted by zombie map
tasks
## What changes were proposed in this pull request?
It seems that old shuffle map tasks hanging around after a stage resubmit
will delete intended shuffle output files on stop(), causing downstream stages
to fail even after successful resubmit completion. This can happen easily if
the prior map task is waiting for a network timeout when its stage is
resubmitted.
This can cause unnecessary stage resubmits, sometimes multiple times, and
very confusing FetchFailure messages that report shuffle index files missing
from the local disk.
Given that IndexShuffleBlockResolver commits data atomically, it seems
unnecessary to ever delete committed task output: even in the rare case that a
task is failed after it finishes committing shuffle output, it should be safe
to retain that output.
## How was this patch tested?
Prior to the fix proposed in https://github.com/apache/spark/pull/14931, I
was able to reproduce this behavior by killing slaves. After this patch, stages
were no longer resubmitted multiple times due to shuffle index loss.
cc @JoshRosen @vanzin
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/ericl/spark dont-remove-committed-files
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14932.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 #14932
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