Manoj Govindassamy created HDFS-12652:
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Summary: INodeAttributesProvider#getAttributes(): Avoid multiple
conversions of path components byte[][] to String[] when requesting INode
attributes
Key: HDFS-12652
URL: https://issues.apache.org/jira/browse/HDFS-12652
Project: Hadoop HDFS
Issue Type: Improvement
Components: hdfs
Affects Versions: 3.0.0-beta1
Reporter: Manoj Govindassamy
Assignee: Manoj Govindassamy
{{INodeAttributesProvider#getAttributes}} needs the path components passed in
to be an array of Strings. Where as the INode and related layers maintain path
components as an array of byte[]. So, these layers are required to convert each
byte[] component of the path back into a string and for multiple times when
requesting for INode attributes from the Provider.
That is, the path "/a/b/c" requires calling the attribute provider with: (1)
"", (2) "", "a", (3) "", "a","b", (4) "", "a","b", "c". Every single one of
those strings were freshly (re)converted from a byte[]. Say, a file listing is
done on a huge directory containing 100s of millions of files, then these
multiple time redundant conversions of byte[][] to String[] create lots of tiny
object garbages, occupying memory and affecting performance. Better if we could
avoid creating redundant copies of path component strings.
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