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From Eric Yang <>
Subject Re: Chukwa customized ReduceProcessor keys
Date Mon, 29 Mar 2010 16:44:29 GMT
Hi Oded,

The current Demux implementation is a prototype, and it is not using
map/reduce effectively.  I would like to refine the partition algorithm to
be partitioned by Time partition + record type + Sampled resolution.

Time partition, and record type are obvious to use multiple reducers to
process different time partitions.  For sampled resolution, this is for
calculating down sampled data resolution concurrently in Demux.  Hence, we
can output at hourly, daily, weekly, and monthly resolutions at the same

This probably should be a subtask of CHUKWA-444.


On 3/28/10 6:52 AM, "Oded Rosen" <> wrote:

> Hey everyone,
> Thanks to your help (especially by Eric & Jerome), I've managed to write my
> own little demux processor, including a customized mapper & reducer, for my
> data type.
> For now, all of my map output is sent to only reduce process (although Chukwa
> opens 8 different reduce processes in each demux run).
> I would like to exploit the whole cluster, and to have multiple reduce
> processes (same reducer class, of course, just many instances of them).
> I've tried to do it by setting different values to ChukwaRecordKey.setKey() in
> my mapper:
> protected void parse(String recordEntry,
>             OutputCollector<ChukwaRecordKey, ChukwaRecord> output,
>             Reporter reporter) throws Throwable {
> key = new ChukwaRecordKey();
> String keyStr = DATA_TYPE + Math.floor((NUM_OF_REDUCERS*Math.random()))+1;
> ChukwaRecord record = new ChukwaRecord();
> this.buildGenericRecord(record, null, timestamp, keyStr);
> key.setKey(keyStr);
> key.setReduceType(ReducerName);
> .... (record logic)....
> output.collect(key, record);
> }
> Although I have multiple keys, all of the records are still sent to the same
> reducer process.
> How can I send records to different processes?
> Thanks a lot,

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