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From Adrian CAPDEFIER <chivas314...@gmail.com>
Subject Re: Job config before read fields
Date Sat, 31 Aug 2013 02:31:13 GMT
But how would the comparator have access to the job config?


On Sat, Aug 31, 2013 at 2:38 AM, Shahab Yunus <shahab.yunus@gmail.com>wrote:

> I think you have to override/extend the Comparator to achieve that,
> something like what is done in Secondary Sort?
>
> Regards,
> Shahab
>
>
> On Fri, Aug 30, 2013 at 9:01 PM, Adrian CAPDEFIER <chivas314159@gmail.com>wrote:
>
>> Howdy,
>>
>> I apologise for the lack of code in this message, but the code is fairly
>> convoluted and it would obscure my problem. That being said, I can put
>> together some sample code if really needed.
>>
>> I am trying to pass some metadata between the map & reduce steps. This
>> metadata is read and generated in the map step and stored in the job
>> config. It also needs to be recreated on the reduce node before the key/
>> value fields can be read in the readFields function.
>>
>> I had assumed that I would be able to override the Reducer.setup()
>> function and that would be it, but apparently the readFields function is
>> called before the Reducer.setup() function.
>>
>> My question is what is any (the best) place on the reduce node where I
>> can access the job configuration/ context before the readFields function is
>> called?
>>
>> This is the stack trace:
>>
>>         at
>> org.apache.hadoop.io.WritableComparator.compare(WritableComparator.java:103)
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.compare(MapTask.java:1111)
>>         at
>> org.apache.hadoop.util.QuickSort.sortInternal(QuickSort.java:70)
>>         at org.apache.hadoop.util.QuickSort.sort(QuickSort.java:59)
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:1399)
>>         at
>> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.flush(MapTask.java:1298)
>>         at
>> org.apache.hadoop.mapred.MapTask$NewOutputCollector.close(MapTask.java:699)
>>         at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:766)
>>         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:415)
>>         at
>> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1149)
>>         at org.apache.hadoop.mapred.Child.main(Child.java:249)
>>
>>
>

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