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https://issues.apache.org/jira/browse/HADOOP-1230?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12620218#action_12620218
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Alejandro Abdelnur commented on HADOOP-1230:
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Got the right code.
Yes, I can see how with the current API option #1 is simpler to implement.
I'm not sure of option #2 with with the current API, it would be error prone if
the developer implements the wrong signature.
What I liked about option #2 was the fact the multiple-outputs were done to the
Context as the standard-output. With the API in the patch I was looking at that
was possible as the Context was parameterized as generic.
On a side note, what is the value of having a inner {{Mapper.Context}} just
extending {{MapContext}} (and the same for {{Reducer}}) but no adding any
methods? Wouldn't be simpler just to use directly the {{MapContext}} in the
{{Mapper}} methods signature (similarly in the {{Reducer}}) ?
> Replace parameters with context objects in Mapper, Reducer, Partitioner,
> InputFormat, and OutputFormat classes
> --------------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-1230
> URL: https://issues.apache.org/jira/browse/HADOOP-1230
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Reporter: Owen O'Malley
> Assignee: Owen O'Malley
> Attachments: context-objs-2.patch, context-objs-3.patch,
> context-objs.patch
>
>
> This is a big change, but it will future-proof our API's. To maintain
> backwards compatibility, I'd suggest that we move over to a new package name
> (org.apache.hadoop.mapreduce) and deprecate the old interfaces and package.
> Basically, it will replace:
> package org.apache.hadoop.mapred;
> public interface Mapper extends JobConfigurable, Closeable {
> void map(WritableComparable key, Writable value, OutputCollector output,
> Reporter reporter) throws IOException;
> }
> with:
> package org.apache.hadoop.mapreduce;
> public interface Mapper extends Closable {
> void map(MapContext context) throws IOException;
> }
> where MapContext has the methods like getKey(), getValue(), collect(Key,
> Value), progress(), etc.
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