[
https://issues.apache.org/jira/browse/HDFS-3934?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13628553#comment-13628553
]
Todd Lipcon commented on HDFS-3934:
-----------------------------------
Quick notes on the patch:
- Why are you using the visitor pattern instead of just exposing getters from
the reader class? Doesn't seem like there's much you're gaining out of it,
since it's just a simple iteration over a list. If you're worried about
exposing internal state, you could make the fields of the reader class
ImmutableMaps -- it looks like they're atomically replaced by refresh() anyway.
- Seems like the refresh code could avoid synchronization until the point where
the new maps are swapped in -- otherwise if the disk is slow during
refreshNodes, or the DNS is slow, any other operations will end up blocking
- New file is missing interface audience and license
I'll let Daryn or someone else who knows this area of the code a bit better
comment on whether the fix is actually semantically correct.
> duplicative dfs_hosts entries handled wrong
> -------------------------------------------
>
> Key: HDFS-3934
> URL: https://issues.apache.org/jira/browse/HDFS-3934
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.0.1-alpha
> Reporter: Andy Isaacson
> Assignee: Andy Isaacson
> Priority: Minor
> Attachments: HDFS-3934.001.patch, HDFS-3934.002.patch,
> HDFS-3934.003.patch, HDFS-3934.004.patch, HDFS-3934.005.patch
>
>
> A dead DN listed in dfs_hosts_allow.txt by IP and in dfs_hosts_exclude.txt by
> hostname ends up being displayed twice in {{dfsnodelist.jsp?whatNodes=DEAD}}
> after the NN restarts because {{getDatanodeListForReport}} does not handle
> such a "pseudo-duplicate" correctly:
> # the "Remove any nodes we know about from the map" loop no longer has the
> knowledge to remove the spurious entries
> # the "The remaining nodes are ones that are referenced by the hosts files"
> loop does not do hostname lookups, so does not know that the IP and hostname
> refer to the same host.
> Relatedly, such an IP-based dfs_hosts entry results in a cosmetic problem in
> the JSP output: The *Node* column shows ":50010" as the nodename, with HTML
> markup {{<a
> href="http://:50075/browseDirectory.jsp?namenodeInfoPort=50070&dir=%2F&nnaddr=172.29.97.196:8020";
> title="172.29.97.216:50010">:50010</a>}}.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
