Ryan Blue created HADOOP-12810:
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Summary: FileSystem#listLocatedStatus causes unnecessary RPC calls
Key: HADOOP-12810
URL: https://issues.apache.org/jira/browse/HADOOP-12810
Project: Hadoop Common
Issue Type: Bug
Components: fs, fs/s3
Affects Versions: 2.7.2
Reporter: Ryan Blue
Assignee: Ryan Blue
{{FileSystem#listLocatedStatus}} lists the files in a directory and then calls
{{getFileBlockLocations(stat.getPath(), ...)}} for each instead of
{{getFileBlockLocations(stat, ...)}}. That function with the path arg just
calls {{getFileStatus}} to get another file status from the path and calls the
file status version, so this ends up calling {{getFileStatus}} unnecessarily.
This is particularly bad for S3, where {{getFileStatus}} is expensive. Avoiding
the extra call improved input split calculation time for a data set in S3 by
~20x: from 10 minutes to 25 seconds.
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