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From Ameya Vilankar <ameya.vilan...@gmail.com>
Subject Re: NPE when trying to register a persistent aggregator
Date Tue, 19 Nov 2013 19:57:34 GMT
I don't understand this part of the code. Can you please explain?

class ReflexivePairMasterCompute extends DefaultMasterCompute {
  registerPersistentAggregator[LongArrayListWriteable]("reflexive_edges",
classOf[LongArrayListAggregator])

registerPersistentAggregator[LongArrayListWriteable]("non_reflexive_edges",
classOf[LongArrayListAggregator]
}

What I would do:
Typically you extend DefaultMasterCompute and then override the initialize
method where you register all the aggregators that you want. Do it like
this.

class ReflexivePairMasterCompute extends DefaultMasterCompute {

    @Override
    public void initialize() throws InstantiationException,
IllegalAccessException {
        registerPersistentAggregator("reflexive_edges",
LongArrayListAggregator.class);
        registerPersistentAggregator("non_reflexive_edges",
LongArrayListAggregator.class);
    }
}




On Mon, Nov 18, 2013 at 11:53 PM, Artie Pesh-Imam <artie.pesh-imam@tapad.com
> wrote:

> Hi all,
>
> Im trying to register a persistent aggregator and am getting a NPE:
> version: Giraph 1.0 running against hadoop 1
>
> java.lang.NullPointerException
> at
> org.apache.giraph.master.MasterCompute.registerPersistentAggregator(MasterCompute.java:152)
>
> class ReflexivePairMasterCompute extends DefaultMasterCompute {
>   registerPersistentAggregator[LongArrayListWriteable]("reflexive_edges",
> classOf[LongArrayListAggregator])
>
> registerPersistentAggregator[LongArrayListWriteable]("non_reflexive_edges",
> classOf[LongArrayListAggregator]
> }
>
> Any ideas? It looks like it’s having issues with the following line, which
> leads me to wonder if I need to do something to init the graph state:
>
> return getGraphState().getGraphTaskManager().getMasterAggregatorUsage().
>         registerPersistentAggregator(name, aggregatorClass);
>
>
> --
> Artie Pesh-Imam
> Software Engineer @ Tapad
> 201-253-9647
>

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