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https://issues.apache.org/jira/browse/HDFS-5698?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13895374#comment-13895374
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Hadoop QA commented on HDFS-5698:
---------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest 
attachment 
  http://issues.apache.org/jira/secure/attachment/12627746/HDFS-5698.007.patch
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author 
tags.

    {color:green}+1 tests included{color}.  The patch appears to include 7 new 
or modified test files.

    {color:green}+1 javac{color}.  The applied patch does not increase the 
total number of javac compiler warnings.

    {color:green}+1 javadoc{color}.  There were no new javadoc warning messages.

    {color:green}+1 eclipse:eclipse{color}.  The patch built with 
eclipse:eclipse.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new 
Findbugs (version 1.3.9) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase 
the total number of release audit warnings.

    {color:red}-1 core tests{color}.  The patch failed these unit tests in 
hadoop-hdfs-project/hadoop-hdfs:

                  
org.apache.hadoop.hdfs.tools.offlineEditsViewer.TestOfflineEditsViewer

    {color:green}+1 contrib tests{color}.  The patch passed contrib unit tests.

Test results: 
https://builds.apache.org/job/PreCommit-HDFS-Build/6083//testReport/
Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/6083//console

This message is automatically generated.

> Use protobuf to serialize / deserialize FSImage
> -----------------------------------------------
>
>                 Key: HDFS-5698
>                 URL: https://issues.apache.org/jira/browse/HDFS-5698
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Haohui Mai
>            Assignee: Haohui Mai
>         Attachments: HDFS-5698-design.pdf, HDFS-5698.000.patch, 
> HDFS-5698.001.patch, HDFS-5698.002.patch, HDFS-5698.003.patch, 
> HDFS-5698.004.patch, HDFS-5698.005.patch, HDFS-5698.006.patch, 
> HDFS-5698.007.patch
>
>
> Currently, the code serializes FSImage using in-house serialization 
> mechanisms. There are a couple disadvantages of the current approach:
> # Mixing the responsibility of reconstruction and serialization / 
> deserialization. The current code paths of serialization / deserialization 
> have spent a lot of effort on maintaining compatibility. What is worse is 
> that they are mixed with the complex logic of reconstructing the namespace, 
> making the code difficult to follow.
> # Poor documentation of the current FSImage format. The format of the FSImage 
> is practically defined by the implementation. An bug in implementation means 
> a bug in the specification. Furthermore, it also makes writing third-party 
> tools quite difficult.
> # Changing schemas is non-trivial. Adding a field in FSImage requires bumping 
> the layout version every time. Bumping out layout version requires (1) the 
> users to explicitly upgrade the clusters, and (2) putting new code to 
> maintain backward compatibility.
> This jira proposes to use protobuf to serialize the FSImage. Protobuf has 
> been used to serialize / deserialize the RPC message in Hadoop.
> Protobuf addresses all the above problems. It clearly separates the 
> responsibility of serialization and reconstructing the namespace. The 
> protobuf files document the current format of the FSImage. The developers now 
> can add optional fields with ease, since the old code can always read the new 
> FSImage.



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