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From "Jason Lowe (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-3360) Provide information about lost nodes in the UI.
Date Tue, 20 Dec 2011 21:51:30 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-3360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13173536#comment-13173536

Jason Lowe commented on MAPREDUCE-3360:

I think, there are only three events, which causes the NM to lost, and all the 3 events have
been handled.
RUNNING -> UNHEALTY, and UNHEALTY -> RUNNING transitions have been handled in their
corresponding transition hooks.

For this comment I'm not worried about the way the decr() method is called with the patch
but rather how it could be mishandled in the future.  Someone could look through the interfaces,
see the decr() method, and assume it will decrement the appropriate counter for the specified
node state.  That's not what this method does; it's only valid to call it with an inactive
state, and if called inappropriately it silently does nothing.  I'm thinking that's undesired
behavior and also wondering if the method is necessary.  There's only one place in the code
where it's called, it seems unlikely to be called in other places legitimately, and the calling
code can do this behavior directly.  This isn't a showstopper issue for me, just a potential
maintenance issue for the future.

bq. For inactive nodes, hyperlink appears as "N/A" however clicking on that does not go anywhere.
 Please once refer the attached screen shot.

I realized the "N/A" hyperlink doesn't fail when clicking it, but then why make it a hyperlink
at all?  It doesn't do anything useful.  For example, we could do something like the following
to only generate a hyperlink when the node is active:

{code:title=in NodesBlock.render() (NodesPage.java)}
        TR<TBODY<TABLE<Hamlet>>> row = tbody.tr().
        if (isInactive) {
        } else {
          String httpAddress = info.getNodeHTTPAddress();
          row.td().a("http://" + httpAddress, httpAddress)._();
              _(StringUtils.byteDesc(usedMemory * BYTES_IN_MB))._().
              _(StringUtils.byteDesc(availableMemory * BYTES_IN_MB))._().

again not a showstopper issue for me, just seemed like we could clean up some useless hyperlinks.

> Provide information about lost nodes in the UI.
> -----------------------------------------------
>                 Key: MAPREDUCE-3360
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-3360
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: mrv2
>    Affects Versions: 0.23.0
>         Environment: NA
>            Reporter: Bh V S Kamesh
>         Attachments: LostNodes.png, MAPREDUCE-3360-1.patch, MAPREDUCE-3360.patch, lostNodes.png
> Currently there is no information provided about *lost nodes*. Provide information in
the UI. 

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