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MapReduce >> mail # user >> Re: Warnings?


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Kevin Burton 2013-04-27, 03:24
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Ted Xu 2013-04-27, 03:49
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Omkar Joshi 2013-04-29, 18:55
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Re: Warnings?
Hi Kevin,

Native libraries are those implemented using C/C++, which only provide code
level portability (instead of binary level portability, as Java do). That
is to say, the binaries provided by CDH4 distribution will in most cases be
broken in your environment.

To check if your native libraries are working or not, you can follow the
instructions I sent previously. Quote as following.

<blockquote>

During runtime, check the hadoop log files for your MapReduce tasks.

   - If everything is all right, then: DEBUG util.NativeCodeLoader - Trying
   to load the custom-built native-hadoop library... INFO
   util.NativeCodeLoader - Loaded the native-hadoop library
   - If something goes wrong, then: INFO util.NativeCodeLoader - Unable to
   load native-hadoop library for your platform... using builtin-java classes
   where applicable

</blokquote>
On Mon, Apr 29, 2013 at 10:21 AM, Kevin Burton <[EMAIL PROTECTED]>wrote:

> I looked at the link you provided and found the Ubuntu is one of the
> “supported platforms” but it doesn’t give any information on how to obtain
> it or build it. Any idea why it is not includde as part of the Cloudera
> CDH4 distribution? I followed the installation instructions (mostly apt-get
> install . . . .) but I fail to see the libhadoop.so.  In order to avoid
> this warning do I need to download the Apache distribution? Which one?****
>
> ** **
>
> For the warnings about the configuration I looked in my configuration and
> for this specific example I don’t see ‘session.id’ used anywhere. It must
> be used by default. If so why is the deprecated default being used? ****
>
> ** **
>
> As for the two warnings about counters. I know I have not implemented any
> code for counters so again this must be something internal. Is there
> something I am doing to trigger this?****
>
> ** **
>
> So I can avoid them what are “hadoop generic options”?****
>
> ** **
>
> Thanks again.****
>
> ** **
>
> Kevin****
>
> ** **
>
> *From:* Ted Xu [mailto:[EMAIL PROTECTED]]
> *Sent:* Friday, April 26, 2013 10:49 PM
> *To:* [EMAIL PROTECTED]
> *Subject:* Re: Warnings?****
>
> ** **
>
> Hi Kevin,****
>
> ** **
>
> Please see my comments inline,****
>
> ** **
>
> On Sat, Apr 27, 2013 at 11:24 AM, Kevin Burton <[EMAIL PROTECTED]>
> wrote:****
>
> Is the native library not available for Ubuntu? If so how do I load it?***
> *
>
> Native libraries usually requires recompile, for more information please
> refer Native Libraries<http://hadoop.apache.org/docs/r2.0.4-alpha/hadoop-project-dist/hadoop-common/NativeLibraries.html>
> . ****
>
> ** **
>
> ** **
>
> Can I tell which key is off? Since I am just starting I would want to be
> as up to date as possible. It is out of date probably because I copied my
> examples from books and tutorials.****
>
> ** **
>
> I think the warning messages are telling it already, "xxx is deprecated,
> use xxx instead...". In fact, most of the configure keys are changed from
> hadoop 1.x to 2.x. The compatibility change may later documented on
> http://wiki.apache.org/hadoop/Compatibility.****
>
>  ****
>
> The main class does derive from Tool. Should I ignore this warning as it
> seems to be in error?****
>
> Of course you can ignore this warning as long as you don't use hadoop
> generic options.****
>
>  ****
>
> ** **
>
> Thank you.****
>
>
> On Apr 26, 2013, at 7:49 PM, Ted Xu <[EMAIL PROTECTED]> wrote:****
>
> Hi,****
>
> ** **
>
> First warning is saying hadoop cannot load native library, usually a
> compression codec. In that case, hadoop will use java implementation
> instead, which is slower.****
>
> ** **
>
> Second is caused by hadoop 1.x/2.x configuration key change. You're using
> a 1.x style key under 2.x, yet hadoop still guarantees backward
> compatibility.****
>
> ** **
>
> Third is saying that the main class of a hadoop application is recommanded
> to implement org.apache.hadoop.util.Tool<http://hadoop.apache.org/docs/current/api/org/apache/hadoop/util/Tool.html>,
> or else generic command line options (e.g., -D options) will not supported.

Regards,
Ted Xu