[
https://issues.apache.org/jira/browse/HDFS-190?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14999310#comment-14999310
]
Steve Loughran commented on HDFS-190:
-------------------------------------
...it was deliberately put into hadoop-common for this reason
> DataNode should be marked as final to prevent subclassing
> ---------------------------------------------------------
>
> Key: HDFS-190
> URL: https://issues.apache.org/jira/browse/HDFS-190
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Steve Loughran
> Priority: Minor
>
> Reviewing the DataNode core, it starts a thread in its constructor calling
> back in to the Run() method. This is generally perceived as very dangerous,
> as if DataNode were ever subclassed, the subclass would start to be invoked
> in the run() method before its own constructor had finished working.
> 1. Consider splitting the constructor from the start() operation.
> 2. If this cannot be changed, mark DataNode as final so nobody can subclass
> it. Though if the latter were done, it would be convenient to have a method
> to let external management components poll for the health of the node, and to
> pick up reasons for the node shutting down.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
