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MapReduce, mail # user - object Writable and Serialization


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Re: object Writable and Serialization
Ted Yu 2010-12-10, 15:50
Old bits:

Can you try adding 'org.apache.hadoop.io.
serializer.JavaSerialization,' to the following config ?
"C:\hadoop-0.20.2\src\core\core-default.xml"(87,9):
  <name>io.serializations</name>

By default, only org.apache.hadoop.io.serializer.WritableSerialization is
included.
On Fri, Dec 10, 2010 at 7:22 AM, <[EMAIL PROTECTED]> wrote:

> Hi,
>
> I know that Hadoop MR don't use the java object Serialization and use
> instead the object Writable, and I understand the reasons that the Hadoop MR
> team chose that.
>
> I was doing my modifications to the Hadoop MR, and I was trying to transfer
> my own object via RPC method call between the TT and the JT.
>
> Here's my object:
> [code]
> // please notice that I use Serializable instead of Writable
> // and I don't implement the method readFields and write neither.
> public class MyObj implements Serializable {
> ...
> }
> [/code]
>
> As consequence this object isn't transfered between the TT and the JT.
>
> Why it isn't transfered? Despite of Hadoop MR don't use java object
> Serialization, this is a feature that belongs to the Java framework.
>
> Thanks,
> PSC