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Posted to common-issues@hadoop.apache.org by "Yang Yang (JIRA)" <ji...@apache.org> on 2012/06/11 05:27:43 UTC
[jira] [Updated] (HADOOP-8503) logic difference between old
mapred.FileInputFormat and mapreduce.lib.input.FileInputFormat
[ https://issues.apache.org/jira/browse/HADOOP-8503?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Yang Yang updated HADOOP-8503:
------------------------------
Description:
in the old mapred.FileInputFormat.getSplits(JobConf, int)
long splitSize = computeSplitSize(goalSize, minSize, blockSize);
so we could control splitSize with the goalSize, which is controlled by mapred.map.tasks
in the new code, mapreduces.lib.input.FileInputFormat
long splitSize = computeSplitSize(blockSize, minSize, maxSize);
i.e. we don't have goal size anymore, furthermore,
the implementation of computeSplitSize() no longer makes sense:
return Math.max(minSize, Math.min(maxSize, blockSize));
since we assume that maxSize is always bigger than minSize, the above line is equivalent to just
return Math.min(maxSize, blockSize), so minSize is useless
> logic difference between old mapred.FileInputFormat and mapreduce.lib.input.FileInputFormat
> -------------------------------------------------------------------------------------------
>
> Key: HADOOP-8503
> URL: https://issues.apache.org/jira/browse/HADOOP-8503
> Project: Hadoop Common
> Issue Type: Bug
> Reporter: Yang Yang
> Priority: Minor
>
> in the old mapred.FileInputFormat.getSplits(JobConf, int)
> long splitSize = computeSplitSize(goalSize, minSize, blockSize);
> so we could control splitSize with the goalSize, which is controlled by mapred.map.tasks
> in the new code, mapreduces.lib.input.FileInputFormat
> long splitSize = computeSplitSize(blockSize, minSize, maxSize);
> i.e. we don't have goal size anymore, furthermore,
> the implementation of computeSplitSize() no longer makes sense:
> return Math.max(minSize, Math.min(maxSize, blockSize));
> since we assume that maxSize is always bigger than minSize, the above line is equivalent to just
> return Math.min(maxSize, blockSize), so minSize is useless
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