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https://issues.apache.org/jira/browse/HDFS-9895?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15195689#comment-15195689
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Colin Patrick McCabe edited comment on HDFS-9895 at 3/15/16 5:13 PM:
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I think this JIRA was misleadingly titled. The patch is about removing the
reference to the {{Configuration}} object inside {{DataNode.java}}, since we
have a reference to the exact same configuration object in the base class. It
doesn't change which aspects of the configuration we cache.
I don't think this affects the thread-safety of anything, or the
reconfiguration logic. Just like before the patch, {{DataNode.java}} is still
playing with a reference to a thread-safe (but mutable) Configuration.
Reconfiguration still happens by means of the {{ReconfigurationThread}}
invoking the {{reconfigureProperty}} method. There is no case where as "swap a
configuration instance"-- the {{Configured}} base class doesn't support
swapping in a new object anyway.
was (Author: cmccabe):
I think this JIRA was misleadingly titled. The patch is about removing the
reference to the {{Configuration}} object inside {{DataNode.java}}, since we
have a reference to the exact same configuration object in the base class. It
doesn't change which aspects of the configuration we cache.
I don't think this affects the thread-safety of anything, or the
reconfiguration logic. Just like before the patch, {{DataNode.java}} is still
playing with a reference to a thread-safe (but mutable) Configuration.
Reconfiguration still happens by means of the {{ReconfigurationThread}}
invoking the {{reconfigureProperty}} method.
> Remove DataNode#conf because there is already a reference to it in the base
> class
> ---------------------------------------------------------------------------------
>
> Key: HDFS-9895
> URL: https://issues.apache.org/jira/browse/HDFS-9895
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode
> Reporter: Xiaobing Zhou
> Assignee: Xiaobing Zhou
> Attachments: HDFS-9895.000.patch
>
>
> Since DataNode inherits ReconfigurableBase with Configured as base class
> where configuration is maintained, DataNode#conf should be removed for the
> purpose of brevity.
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