[
https://issues.apache.org/jira/browse/HADOOP-3221?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Robert Chansler updated HADOOP-3221:
------------------------------------
Release Note: Added org.apache.hadoop.mapred.lib.NLineInputFormat ,which
splits N lines of input as one split. N can be specified by configuration
property "mapred.line.input.format.linespermap", which defaults to 1. (was:
Adds org.apache.hadoop.mapred.lib.NLineInputFormat ,which splits N lines of
input as one split. N can be specified by configuration property
"mapred.line.input.format.linespermap", which defaults to 1.)
> Need a "LineBasedTextInputFormat"
> ---------------------------------
>
> Key: HADOOP-3221
> URL: https://issues.apache.org/jira/browse/HADOOP-3221
> Project: Hadoop Core
> Issue Type: New Feature
> Components: mapred
> Affects Versions: 0.16.2
> Environment: All
> Reporter: Milind Bhandarkar
> Assignee: Amareshwari Sriramadasu
> Fix For: 0.18.0
>
> Attachments: patch-3221-1.txt, patch-3221-2.txt, patch-3221.txt
>
>
> In many "pleasantly" parallel applications, each process/mapper processes the
> same input file (s), but with computations are controlled by different
> parameters.
> (Referred to as "parameter sweeps").
> One way to achieve this, is to specify a set of parameters (one set per line)
> as input in a control file (which is the input path to the map-reduce
> application, where as the input dataset is specified via a config variable in
> JobConf.).
> It would be great to have an InputFormat, that splits the input file such
> that by default, one line is fed as a value to one map task, and key could be
> line number. i.e. (k,v) is (LongWritable, Text).
> If user specifies the number of maps explicitly, each mapper should get a
> contiguous chunk of lines (so as to load balance between the mappers.)
> The location hints for the splits should not be derived from the input file,
> but rather, should span the whole mapred cluster.
> (Is there a way to do this without having to return an array of
> nSplits*nTaskTrackers ?)
> Increasing the replication of the "real" input dataset (since it will be
> fetched by all the nodes) is orthogonal, and one can use DistributedCache for
> that.
> (P.S. Please chose a better name for this InputFormat. I am not in love with
> "LineBasedText" name.)
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
