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From john smith <js1987.sm...@gmail.com>
Subject Re: Issue with loading the Snappy Codec
Date Sun, 15 Apr 2012 10:04:06 GMT
Can you restart tasktrackers once and run the job again? It refreshes the
class path.

On Sun, Apr 15, 2012 at 11:58 AM, Bas Hickendorff
<hickendorffbas@gmail.com>wrote:

> Thanks.
>
> The native snappy libraries I have installed. However, I use the
> normal jars that you get when downloading Hadoop, I am not compiling
> Hadoop myself.
>
> I do not want to use the snappy codec (I don't care about compression
> at the moment), but it seems it is needed anyway? I added this to the
> mapred-site.xml:
>
> <property>
>        <name>mapred.compress.map.output</name>
>        <value>false</value>
> </property>
>
> But it still fails with the error of my previous email (SnappyCodec not
> found).
>
> Regards,
>
> Bas
>
>
> On Sat, Apr 14, 2012 at 6:30 PM, Vinod Kumar Vavilapalli
> <vinodkv@hortonworks.com> wrote:
> >
> > Hadoop has integrated snappy via installed native libraries instead of
> snappy-java.jar (ref https://issues.apache.org/jira/browse/HADOOP-7206)
> >  - You need to have the snappy system libraries (snappy and
> snappy-devel) installed before you compile hadoop. (RPMs are available on
> the web, http://pkgs.org/centos-5-rhel-5/epel-i386/21/ for example)
> >  - When you build hadoop, you will need to compile the native
> libraries(by passing -Dcompile.native=true to ant) to avail snappy support.
> >  - You also need to make sure that snappy system library is available on
> the library path for all mapreduce tasks at runtime. Usually if you install
> them on /usr/lib or /usr/local/lib, it should work.
> >
> > HTH,
> > +Vinod
> >
> > On Apr 14, 2012, at 4:36 AM, Bas Hickendorff wrote:
> >
> >> Hello,
> >>
> >> When I start a map-reduce job, it starts, and after a short while,
> >> fails with the error below (SnappyCodec not found).
> >>
> >> I am currently starting the job from other Java code (so the Hadoop
> >> executable in the bin directory is not used anymore), but in principle
> >> this seems to work (in the admin of the Jobtracker the job shows up
> >> when it starts). However after a short while the map task fails with:
> >>
> >>
> >> java.lang.IllegalArgumentException: Compression codec
> >> org.apache.hadoop.io.compress.SnappyCodec not found.
> >>       at
> org.apache.hadoop.io.compress.CompressionCodecFactory.getCodecClasses(CompressionCodecFactory.java:96)
> >>       at
> org.apache.hadoop.io.compress.CompressionCodecFactory.<init>(CompressionCodecFactory.java:134)
> >>       at
> org.apache.hadoop.mapreduce.lib.input.LineRecordReader.initialize(LineRecordReader.java:62)
> >>       at
> org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.initialize(MapTask.java:522)
> >>       at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:763)
> >>       at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
> >>       at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
> >>       at java.security.AccessController.doPrivileged(Native Method)
> >>       at javax.security.auth.Subject.doAs(Subject.java:416)
> >>       at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1093)
> >>       at org.apache.hadoop.mapred.Child.main(Child.java:249)
> >> Caused by: java.lang.ClassNotFoundException:
> >> org.apache.hadoop.io.compress.SnappyCodec
> >>       at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
> >>       at java.security.AccessController.doPrivileged(Native Method)
> >>       at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
> >>       at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
> >>       at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
> >>       at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
> >>       at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
> >>       at java.lang.Class.forName0(Native Method)
> >>       at java.lang.Class.forName(Class.java:264)
> >>       at
> org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:820)
> >>       at
> org.apache.hadoop.io.compress.CompressionCodecFactory.getCodecClasses(CompressionCodecFactory.java:89)
> >>       ... 10 more
> >>
> >>
> >> I confirmed that the SnappyCodec class is present in the
> >> hadoop-core-1.0.2.jar, and the snappy-java-1.0.4.1.jar is present as
> >> well. The directory of those jars is on the HADOOP_CLASSPATH, but it
> >> seems it still cannot find it. I also checked that the config files of
> >> Hadoop are read. I run all nodes on localhost.
> >>
> >> Any suggestions on what could be the cause of the issue?
> >>
> >> Regards,
> >>
> >> Bas
> >
>

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