Nice find! That's a bug. I opened up GIRAPH-113 with your solution (I
believe it is correct). I'll have to wait for someone to +1 it before a
commit.
Avery
On 12/20/11 6:07 PM, Yuanyuan Tian wrote:
Hi,
I decided to use LongDoubleFloatDoubleVertex in a graph algorithm
because it uses more compact and efficient mahout collections. However
I run into an error when running the algorithm:
java.lang.ClassCastException:
org.apache.giraph.graph.LongDoubleFloatDoubleVertex cannot be cast to
org.apache.giraph.graph.Vertex
at
org.apache.giraph.comm.BasicRPCCommunications.prepareSuperstep(BasicRPCCommunications.java:1016)
at
org.apache.giraph.graph.BspServiceWorker.startSuperstep(BspServiceWorker.java:843)
at org.apache.giraph.graph.GraphMapper.map(GraphMapper.java:569)
at org.apache.giraph.graph.GraphMapper.run(GraphMapper.java:728)
... 7 more
Basically, the problem is that in
BasicRPCCommunications.prepareSuperStep(), the
LongDoubleFloatDoubleVertex are cast to Vertex in the following code
fragment. But LongDoubleFloatDoubleVertex inherits from BasicVertex
instead of Vertex.
*if* (vertex != *null*) {
((MutableVertex<I, V, E, M>) vertex).setVertexId(vertexIndex);
partition.putVertex((Vertex<I, V, E, M>) vertex);
} *else**if* (originalVertex != *null*) {
partition.removeVertex(originalVertex.getVertexId());
}
I did a simple change: cast LongDoubleFloatDoubleVertex to
BasicVertex. The problem went away, and the algorithm finished without
any error. But I am not sure this change has any implication to other
parts of the code. So, I hope to get some comments from the Giraph
developers.
*if* (vertex != *null*) {
((MutableVertex<I, V, E, M>) vertex).setVertexId(vertexIndex);
partition.putVertex((BasicVertex<I, V, E, M>) vertex);
} *else**if* (originalVertex != *null*) {
partition.removeVertex(originalVertex.getVertexId());
}
Thanks,
Yuanyuan Tian
Research Staff Member
IBM Almaden Research Center
650 Harry Road
San Jose, California 95120-6099
(408) 927-1704
