Can you show me an example of the inner Context class idea? Sounds
interesting...
Another question is whether to have the
(pre|post)(Application|Superstep)() methods executed one as an aggregate
and passed to the workers, or executed per worker. I think the former
might be a little expensive, depending on how big the "Context" is.
Perhaps executed per worker makes the most sense. Any other thoughts?
Maybe aggregator methods would be useful as well, say to do this like
write the aggregators for the entire application every now and then.
That would probably get executed on the master. I think the current
uses of the (pre|post)(Application|Superstep)() methods are fine in the
per-worker specific way of thinking.
Avery
On 10/1/11 7:06 AM, Jake Mannix wrote:
On Sat, Oct 1, 2011 at 2:29 AM, Hyunsik Choi <hyun...@apache.org
<mailto:hyun...@apache.org>> wrote:
Now, that way looks good. Probably, later we could improve that
like Context
of MapReduce.
ooooooh! I really that suggestion, actually. If every BasicVertex has an
inner Context class, we can allow user applications to define/extend their
Context and we can avoid even doing any of this setClass() and reflection
based stuff, if we do it right. Typesafe context object FTW!
-jake
--
Hyunsik Choi
Database Lab, Korea University
On Sat, Oct 1, 2011 at 3:01 AM, Avery Ching <ach...@apache.org
<mailto:ach...@apache.org>> wrote:
> 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
> GiraphJob
>
> final public void setWorkerObjectClass(Class<? extends Configurable>
> workerObjectClass);
>
> 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?
>
> Avery
>
> 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<jake.man...@gmail.com <mailto:jake.man...@gmail.com>>
>> 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
>>> <claudio.marte...@gmail.com
<mailto:claudio.marte...@gmail.com>> 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
>>>> claudio.marte...@gmail.com <mailto:claudio.marte...@gmail.com>
>>>
>>
>>
>
>
