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MapReduce >> mail # user >> OutputValueGroupingComparator gets strange inputs (topic changed from "Logs cannot be created")


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Re: OutputValueGroupingComparator gets strange inputs (topic changed from "Logs cannot be created")
I would recommend you to look at the yahoo tutorial for more information.

Here is the part we are discussing about :
http://developer.yahoo.com/hadoop/tutorial/module5.html#writable-comparator

Regards

Bertrand

On Thu, Aug 9, 2012 at 5:03 PM, Björn-Elmar Macek <[EMAIL PROTECTED]>wrote:

>  Hi Bertrand,
>
> i am using RawComperator because this one was used in the tutorial of some
> famous (hadoop) guy describing how to sort the input for the reducer. Is
> there an easier alternative?
>
>
> Am 09.08.2012 16:57, schrieb Bertrand Dechoux:
>
> I am just curious but are you using Writable? If so there is a
> WritableComparator...
> If you are going to interpret every bytes (you create a String, so you
> do), there no clear reason for choosing such a low level API.
>
> Regards
>
> Bertrand
>
> On Thu, Aug 9, 2012 at 4:47 PM, Björn-Elmar Macek <[EMAIL PROTECTED]>wrote:
>
>> Hi again,
>>
>> this is an direct response to my previous posting with the title "Logs
>> cannot be created", where logs could not be created (Spill failed). I got
>> the hint, that i gotta check privileges, but that was not the problem,
>> because i own the folders that were used for this.
>>
>> I finally found an important hint in a log saying:
>> 12/08/09 15:30:49 WARN mapred.JobClient: Error reading task outputhttp://
>> its-cs229.its.uni-kassel.de:50060/tasklog?plaintext=true&attemptid=attempt_201208091516_0001_m_000048_0&filter=stdout
>> 12/08/09 15:30:49 WARN mapred.JobClient: Error reading task outputhttp://
>> its-cs229.its.uni-kassel.de:50060/tasklog?plaintext=true&attemptid=attempt_201208091516_0001_m_000048_0&filter=stderr
>> 12/08/09 15:34:34 INFO mapred.JobClient: Task Id :
>> attempt_201208091516_0001_m_000055_0, Status : FAILED
>> java.io.IOException: Spill failed
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1029)
>>         at
>> org.apache.hadoop.mapred.MapTask$OldOutputCollector.collect(MapTask.java:592)
>>         at
>> uni.kassel.macek.rtprep.RetweetMapper.map(RetweetMapper.java:26)
>>         at
>> uni.kassel.macek.rtprep.RetweetMapper.map(RetweetMapper.java:12)
>>         at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
>>         at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:436)
>>         at org.apache.hadoop.mapred.MapTask.run(MapTask.java:372)
>>         at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
>>         at java.security.AccessController.doPrivileged(Native Method)
>>         at javax.security.auth.Subject.doAs(Subject.java:396)
>>         at
>> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1093)
>>         at org.apache.hadoop.mapred.Child.main(Child.java:249)
>> Caused by: java.lang.NumberFormatException: For input string: ""
>>         at
>> java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
>>         at java.lang.Integer.parseInt(Integer.java:468)
>>         at java.lang.Integer.parseInt(Integer.java:497)
>>         at uni.kassel.macek.rtprep.Tweet.getRT(Tweet.java:126)
>>         at
>> uni.kassel.macek.rtprep.TwitterValueGroupingComparator.compare(TwitterValueGroupingComparator.java:47)
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.compare(MapTask.java:1111)
>>         at
>> org.apache.hadoop.util.QuickSort.sortInternal(QuickSort.java:95)
>>         at org.apache.hadoop.util.QuickSort.sort(QuickSort.java:59)
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:1399)
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.access$1800(MapTask.java:853)
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer$SpillThread.run(MapTask.java:1344)
>>
>>
>>
>> corresponding to the following lines of code within the class
>> TwitterValueGroupingComparator:
>>
>> public class TwitterValueGroupingComparator implements
>> RawComparator<Text> {
>> ...
>>     public int compare(byte[] text1, int start1, int length1, byte[]
Bertrand Dechoux