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Created December 28, 2015 15:16
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sync_col_70
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hadoop
Title:
NNStorage does not synchronize iteration on a synchronized list
Body:
In line 839 of NNStroage.java#reportErrorsOnDirectories, the synchronized list, `sds`
is iterated in an unsynchronized manner, but according to [Oracle Java 7 API specification]
(http://docs.oracle.com/javase/7/docs/api/java/util/Collections.html#synchronizedList(java.util.List)),
this is not thread-safe and can lead to non-deterministic behavior.
This pull request adds a fix by synchronizing the iteration on `sds`. The synchronized list is passed to method `reportErrorsnODirectories` from
[here](https://github.com/facebookarchive/hadoop-20/blob/2a29bc6ecf30edb1ad8dbde32aa49a317b4d44f4/src/hdfs/org/apache/hadoop/hdfs/server/namenode/FSImage.java#L508)
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