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https://issues.apache.org/jira/browse/HADOOP-1230?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12573973#action_12573973
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Owen O'Malley commented on HADOOP-1230:
---------------------------------------
{quote}
* Mapper & Reducer are no longer JobConfigurable, was that intentional?
{quote}
Yes, it was intentional. With ReflectionUtils, we configure objects if the
run-time type is Configurable or JobConfigurable. So we don't need to declare
it in the interface.
{quote}
* Another benefit of contexts is that we can avoid serialization. Should we
add raw binary i/o from the outset, or add that in a subsequent pass?
{quote}
I was going to add it later, but I guess I should add it now. It would mean
that there is:
{code}
BytesWritable getRawKey() throws IOException;
BytesWritable getRawValue() throws IOException;
void collectRaw(BytesWritable key, BytesWritable value) throws IOException;
{code}
I guess at that point, I could redo the IdentityMapper and IdentityReducer to
pass along raw values.
> 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.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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