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From Avery Ching <>
Subject Re: On pre/post Application/Superstep contract
Date Fri, 30 Sep 2011 18:01:24 GMT
It isn't visible (purposefully) since it is internal state.

That being said, I believe this type of functionality would be useful.  
Right now there is a lot of ugly static variables stored in Vertex 
implementations because of it.  Perhaps we should add another method in 

final public void setWorkerObjectClass(Class<? extends Configurable> 

Then in BasicVertex

public void preApplication(Configurable workerObject);
public void postApplication(Configurable workerObject);
public void preSuperstep(Configurable workerObject);
public void postSuperstep(Configurable workerObject);
public Configurable getWorkerObject();

Anyone else think of a cleaner way to do it?


On 9/30/11 8:42 AM, Claudio Martella wrote:
> afaik getGraphState() is not visible to my object. Or?
> On Fri, Sep 30, 2011 at 5:23 PM, Jake Mannix<>  wrote:
>> Remember that there's already a "singleton"-like object available to all
>> vertices: the GraphState object, which has a handle on the GraphMapper.
>> Maybe this is the right place to get your handle on the FSDataOutputStream?
>>    -jake
>> On Fri, Sep 30, 2011 at 7:25 AM, Claudio Martella
>> <>  wrote:
>>> Hello,
>>> to my understanding pre/post Application/Superstep methods are called
>>> ONCE on a "fake" vertex on each worker (the so called
>>> representativeVertex). This means that these methods should not depend
>>> on any specific-vertex data.
>>> As I'm trying to sort out my Emitter, I thought I could create one
>>> FSDataOutputStream per worker which each Vertex belonging to that
>>> worker could share (which would be even thread-safe as each worker is
>>> not parallel).
>>> The questions are:
>>> 1) how to share the FSDataOutputFormat object created at
>>> preApplication() (and closed at postApplication()) created by this
>>> representativeVertex?
>>> 2) about the filename, I'd be happy to have access to the Worker Id so
>>> to create an outputfile filename as with happens with reducers and
>>> part files by FileOutputFormat (i.e.<userdefinedfilename>-workerid).
>>> The "best" idea i have in my mind right now is to use the calling
>>> vertex (the representativeVertex) hashCode as the id, and create an
>>> external Singleton where i can request register and request the
>>> outputfiles similarly to what happens with Aggregators now, and by
>>> passing the *this* reference as an index to this map. Any better idea?
>>> :)
>>> --
>>>      Claudio Martella

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