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https://issues.apache.org/jira/browse/HDFS-3574?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13406742#comment-13406742
]
Hudson commented on HDFS-3574:
------------------------------
Integrated in Hadoop-Mapreduce-trunk-Commit #2439 (See
[https://builds.apache.org/job/Hadoop-Mapreduce-trunk-Commit/2439/])
HDFS-3574. Fix small race and do some cleanup in GetImageServlet.
Contributed by Todd Lipcon. (Revision 1356939)
Result = FAILURE
todd : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1356939
Files :
*
/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/ServletUtil.java
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/GetImageServlet.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/TransferFsImage.java
> Fix small race and do some cleanup in GetImageServlet
> -----------------------------------------------------
>
> Key: HDFS-3574
> URL: https://issues.apache.org/jira/browse/HDFS-3574
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: name-node
> Affects Versions: 3.0.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Minor
> Fix For: 2.0.1-alpha
>
> Attachments: hdfs-3574.txt, hdfs-3574.txt, hdfs-3574.txt,
> hdfs-3574.txt
>
>
> There's a very small race window in GetImageServlet, if the following
> interleaving occurs:
> - The Storage object returns some local file in the storage directory (eg an
> edits file or image file)
> - *Race*: some other process removes the file
> - GetImageServlet calls file.length() which returns 0, since it doesn't
> exist. It thus faithfully sets the Content-Length header to 0
> - getFileClient() throws FileNotFoundException when trying to open the file.
> But, since we call response.getOutputStream() before this, the headers have
> already been sent, so we fail to send the "404" or "500" response that we
> should.
> Thus, the client sees a 0-length Content-Length followed by 0 lengths of
> content, and thinks it successfully has downloaded the target file, where in
> fact it downloads an empty one.
> I saw this in practice during the "edits synchronization" phase of recovery
> while working on HDFS-3077, though it could apply on existing code paths, as
> well, I believe.
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