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From Zuhair Khayyat <zuhair.khay...@kaust.edu.sa>
Subject Re: hanging context.write() with large arrays
Date Sat, 05 May 2012 14:55:23 GMT
Thanks for the fast response.. I think it is a good idea, however the
application becomes too slow with large output arrays. I would be more
interested in a solution that helps speeding up the "context.write()" it

On Sat, May 5, 2012 at 5:36 PM, Zizon Qiu <zzdtsv@gmail.com> wrote:

> for the timeout problem,you can use a background thread that invoke
> context.progress() timely which do "keep-alive" for forked
> Child(mapper/combiner/reducer)...
> it is tricky but works.
> On Sat, May 5, 2012 at 10:05 PM, Zuhair Khayyat <
> zuhair.khayyat@kaust.edu.sa> wrote:
>> Hi,
>> I am building a MapReduce application that constructs the adjacency list
>> of a graph from an input edge list. I noticed that my Reduce phase always
>> hangs (and timeout eventually) as it calls the function
>> context.write(Key_x,Value_x) when the Value_x is a very large ArrayWritable
>> (around 4M elements). I have increased both "mapred.task.timeout" and the
>> Reducers memory but no luck; the reducer does not finish the job. Is there
>> any other data format that supports large amount of data or should I use my
>> own "OutputFormat" class to optimize writing the large amount of data?
>> Thank you.
>> Zuhair Khayyat

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