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https://issues.apache.org/jira/browse/HDFS-7457?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14277432#comment-14277432
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Daryn Sharp commented on HDFS-7457:
-----------------------------------
It's not the int that is subject to GC, but the dynamic construction of the
xferAddr string per the description. This caches the string and recomputes the
hash if/when it changes.
> DatanodeID generates excessive garbage
> --------------------------------------
>
> Key: HDFS-7457
> URL: https://issues.apache.org/jira/browse/HDFS-7457
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.0.0-alpha, 3.0.0
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Attachments: HDFS-7457.patch
>
>
> {{DatanodeID#getXferAddr}} is a dynamically generated string. This string is
> repeatedly generated for the hash code, equality, comparisons, and
> stringification. Every DN->NN RPC method calls
> {{DatanodeManager#getDatanode}} to validate if the node is registered, which
> involves a call to {{getXferAddr}}.
> The dynamic computation generates unnecessary trash that puts unnecessary
> pressure on the GC.
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