GitHub user zsxwing opened a pull request:
https://github.com/apache/spark/pull/5136
[SPARK-6468][Block Manager] Fix the race condition of subDirs in
DiskBlockManager
There are two race conditions of `subDirs` in `DiskBlockManager`:
1. `getAllFiles` does not use correct locks to read the contents in
`subDirs`. Although it's designed for testing, it's still worth to add correct
locks to eliminate the race condition.
2. The double-check has a race condition in `getFile(filename: String)`. If
a thread finds `subDirs(dirId)(subDirId)` is not null out of the `synchronized`
block, it may not be able to see the correct content of the File instance
pointed by `subDirs(dirId)(subDirId)` according to the Java memory model (there
is no volatile variable here).
This PR fixed the above race conditions.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/zsxwing/spark SPARK-6468
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/5136.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 #5136
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commit cbb872b869d03e6da900cc84fee6410c0709a988
Author: zsxwing <[email protected]>
Date: 2015-03-23T12:39:47Z
Fix the race condition of subDirs in DiskBlockManager
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