hadoop-mapreduce-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-326) The lowest level map-reduce APIs should be byte oriented
Date Fri, 12 Feb 2010 23:59:28 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833251#action_12833251
] 

Owen O'Malley commented on MAPREDUCE-326:
-----------------------------------------

{quote}
This is not a risk since the API is marked "unstable" so we retain the freedom to change it
in any way we like. 
{quote}

That is completely untrue. It is mark unstable as a warning to users. I would reject any incompatible
change to the API. We should mark the base classes (Mapper, Reducer, InputFormat, OutputFormat,
Partitioner, RecordReader, RecordWriter, Partitioner, *Context) as stable. Pig is already
using the new APIs and so are a lot of other business critical applications.

{quote}
You can think of this change as a refactor to make the MapReduce shuffle more accessible to
framework developers
{quote}

My suggestion does it far more easily and with no application disruption.

Furthermore, this *does* double the interface, which is already extremely wide.

{quote}
the new (context objects) MapReduce API is implemented in library code
{quote}

But it is the primary interface that our users use. If you are proposing that we make this
the "real" interface, then I've already expressed my -1. Users don't want to think in bytes.



 



> The lowest level map-reduce APIs should be byte oriented
> --------------------------------------------------------
>
>                 Key: MAPREDUCE-326
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-326
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>            Reporter: eric baldeschwieler
>         Attachments: MAPREDUCE-326-api.patch, MAPREDUCE-326.pdf
>
>
> As discussed here:
> https://issues.apache.org/jira/browse/HADOOP-1986#action_12551237
> The templates, serializers and other complexities that allow map-reduce to use arbitrary
types complicate the design and lead to lots of object creates and other overhead that a byte
oriented design would not suffer.  I believe the lowest level implementation of hadoop map-reduce
should have byte string oriented APIs (for keys and values).  This API would be more performant,
simpler and more easily cross language.
> The existing API could be maintained as a thin layer on top of the leaner API.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message