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From Jyoti Yadav <rao.jyoti26ya...@gmail.com>
Subject Re: about retaining the variable value...
Date Sun, 17 Nov 2013 10:17:36 GMT
Thanks Ameya...I will give a try to your ideas...


On Sun, Nov 17, 2013 at 3:17 PM, Ameya Vilankar <ameya.vilankar@gmail.com>wrote:

> In your scenario, you want to store some value that is obtained in
> Superstep 1, so that it is available to a vertex in all the subsequent
> supersteps. The best place to do that is to store it on the vertex itself.
> The simplest example is ShortesPath Example where you store the current
> lowest distance on the vertex, and when you receive a message you update it
> with the new lowest mistake. I assume that in your program you don't want
> to update the value after Superstep 1. So don't. Just keep an extra
> variable in your vertex value class and set it in superstep 1 so that it
> can be used by the vertex in all the following steps.
>
> But if you want to store global information i.e in superstep 1, every
> vertex computes and stores a value and in the subsequent supersteps, a
> vertex needs access to the stored values of all the vertices, you need to
> make those values global. The only way to do it is to use a persistent
> aggregator. In superstep 1, every vertex computes the value and then sends
> it to the persistent aggregator that can contain a hashmap from the vertex
> id to the value. This value will persist across all the supersteps since
> the aggregator is a persistent one. Will be available to every vertex too.
>
>
> On Sun, Nov 17, 2013 at 1:11 AM, Mirko Kämpf <mirko.kaempf@cloudera.com>wrote:
>
>> Hi,
>>
>> if it is a local value, just important for that given vertex, it might
>> work with a local variable, maybe even a more complex data structure, e.g.
>> a Stack or a FIFO buffer, to handle "old" data. I do not consider to
>> exchange data between vertexes, only within one vertex over time.
>>
>> I write this here, to share my idea, but I am not really sure if a Giraph
>> vertex works like this. It's just how I would try it ...
>>
>> But I think we will see a definitive answer soon.
>>
>> Have a nice day!
>> Mirko
>>
>>
>> On Sun, Nov 17, 2013 at 6:55 AM, Jyoti Yadav <rao.jyoti26yadav@gmail.com>wrote:
>>
>>> Hi folks...
>>>
>>> while executing my program ,i came across a doubt which is creating
>>> problem...
>>>
>>> Scenario....
>>>
>>> In compute() function,
>>> Suppose in superstep1 each vertex want to save some value so that every
>>> vertex can use its  previously saved value in upcoming supersteps...Is it
>>> possible???
>>>
>>>
>>> Any ideas are really appreciated...
>>>
>>> Thanks...
>>> Jyoti
>>>
>>>
>>>
>>>
>>
>>
>>
>

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