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From "Xiao Chen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9519) Some coding improvement in SecondaryNameNode#main
Date Thu, 10 Dec 2015 03:38:10 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9519?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15049978#comment-15049978
] 

Xiao Chen commented on HDFS-9519:
---------------------------------

Thanks Yongjun. I agree with your general idea that we should focus on the 2 modes instead
of the web server itself. Quick clarification:
'Run as a daemon' is not limited to 'no command is specified' - if {{-format}} is given, after
{{parseArgs}}, {{opts.getCommand()}} still returns null so that 2NN is still started as a
daemon.
Uploaded patch 2 which I think explains it clearer. Please let me know what you think.

> Some coding improvement in SecondaryNameNode#main
> -------------------------------------------------
>
>                 Key: HDFS-9519
>                 URL: https://issues.apache.org/jira/browse/HDFS-9519
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>            Reporter: Yongjun Zhang
>            Assignee: Xiao Chen
>         Attachments: HDFS-9519.01.patch, HDFS-9519.02.patch
>
>
> Two nits:
> # The checking whether secondary is null is not necessary in the following code in SecondaryNameNode.java.

> # The comment in this code seems to imply that "when secondary is not null, SNN was stared
as a daemon.", and this is not true. Suggest to improve the comment to make it clear,
> Assign to Xiao since he worked on HDFS-3059. Thanks Xiao.
> {code}
>       if (secondary != null) {
>         // The web server is only needed when starting SNN as a daemon,
>         // and not needed if called from shell command. Starting the web server
>         // from shell may fail when getting credentials, if the environment
>         // is not set up for it, which is most of the case.
>         secondary.startInfoServer();
>         secondary.startCheckpointThread();
>         secondary.join();
>       }
> {code}



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