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Date: Fri, 02 Mar 2012 15:15:40 -0800
From: Avery Ching <aching@apache.org>
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To: giraph-user@incubator.apache.org
Subject: Re: Error in instantiating custom Vertex class via
 InternalVertexRunner.run
References: <F57EEDFE-9E04-4B5B-B825-C6DF45E01B78@deri.org>
In-Reply-To: <F57EEDFE-9E04-4B5B-B825-C6DF45E01B78@deri.org>
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If I'm reading this right, you're using a public abstract class for the 
vertex.  The vertex class must be instantiable and cannot be abstract.

Hope that helps,

Avery

On 3/2/12 11:51 AM, Benjamin Heitmann wrote:
> Hello,
>
> in the last week I started working with Apache Giraph. My goal is to implement a version of the
> spreading activation algorithm (as described on Wikipedia [1] and in this article [2] ).
> Using Giraph will hopefully allow scaling for Linked Data/RDF from DBPedia.
>
> I used the ConnectedComponentsVertex Example (and its UnitTest) as the
> starting point for my own Vertex, TextInputFormat, TextOutputFormat and UnitTest (and a class for VertexData/State).
> In addition, I ensured that the ConnectedComponentsVertexTest runs successfully, both from the giraph source tree
> and from my own project.
>
> My Vertex class is called SpreadingActivationVertex, and it directly extends BasicVertex, and it has the following<I, V, E, M>  signature:
> public abstract class SpreadingActivationVertex extends
> BasicVertex<IntWritable, SpreadingActivationStateWritable, NullWritable, DoubleWritable>
> As you can see, I need to maintain more then one variable for the state of the vertex,
> and I need to pass doubles as messages.
>
> When I execute my UnitTest, I get the following error:
>
> 59820 [Thread-4] WARN  org.apache.hadoop.mapred.LocalJobRunner  - job_local_0001
> java.lang.RuntimeException: java.lang.InstantiationException
> 	at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:115)
> 	at org.apache.giraph.graph.BspUtils.createVertex(BspUtils.java:365)
> 	at ie.deri.uimr.ld_sa.prototyping.giraph.SpreadingActivationTextInputFormat$SpreadingActivationVertexReader.getCurrentVertex(SpreadingActivationTextInputFormat.java:53)
> 	at org.apache.giraph.graph.BspServiceWorker.readVerticesFromInputSplit(BspServiceWorker.java:440)
> 	at org.apache.giraph.graph.BspServiceWorker.loadVerticesFromInputSplit(BspServiceWorker.java:371)
> 	at org.apache.giraph.graph.BspServiceWorker.loadVertices(BspServiceWorker.java:305)
> 	at org.apache.giraph.graph.BspServiceWorker.setup(BspServiceWorker.java:583)
> 	at org.apache.giraph.graph.GraphMapper.setup(GraphMapper.java:474)
> 	at org.apache.giraph.graph.GraphMapper.run(GraphMapper.java:646)
> 	at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:763)
> 	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:369)
> 	at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:210)
> Caused by: java.lang.InstantiationException
> 	at sun.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(InstantiationExceptionConstructorAccessorImpl.java:30)
> 	at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
> 	at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:113)
> 	... 11 more
>
>
> Using the eclipse debugger, I traced it to these lines of code in Hadoop:
>
> org.apache.hadoop.util.ReflectionUtils, line 113 in newInstance():
>
>      try {
>        Constructor<T>  meth = (Constructor<T>) CONSTRUCTOR_CACHE.get(theClass);
>        if (meth == null) {
>          meth = theClass.getDeclaredConstructor(EMPTY_ARRAY);
>          meth.setAccessible(true);
>          CONSTRUCTOR_CACHE.put(theClass, meth);
>        }
>        result = meth.newInstance();    //<<<------------ this is the line causing the error
>      } catch (Exception e) {
>        throw new RuntimeException(e);
>      }
>
> The constructor cache does not contain my vertex class, however the next lines successfully find the right constructor and put it into "meth".
> However, the invocation of meth.newInstance() fails with the above error.
>
>
> Did somebody have this error before ?
> What did I miss ?
> The class itself is successfully found, so it is not an issue of setting some paths.
> However getting a newInstance seems to fail for some reason.
>
> Would it be helpful if I provide the code for my 5 classes somewhere ? If yes, in which way would that be convenient for this mailing list ?
>
>
>
> [1] https://en.wikipedia.org/wiki/Spreading_activation
> [2] http://linkinghub.elsevier.com/retrieve/pii/0306457387900173
>