Large scale graph processing with apache giraph

Transcript

1. Large scale graph processing with apache giraph André Kelpe @fs111

   http://kel.pe

2. graphs 101

3. vertices and edges

4. v2 v5 v4 v7 v3 v8 v6 v1 v9 v8

   v10 simple graph

5. graphs are everywhere road network, the www, social graphs etc.

6. graphs can be huge

7. google knows!

8. Pregel

9. Pregel by google Describes graph processing approach based on BSP

   (Bulk Synchronous Parallel)

10. pro-tip: search for „pregel_paper.pdf“ on github ;-)

11. Properties of Pregel batch-oriented, scalable, fault tolerant processing of graphs

12. It is not a graph database It is a processing

    framework

13. BSP vertex centric processing in so called supersteps

14. BSP vertices send messages to each other

15. BSP synchronization points between supersteps

16. execution of superstep S Each vertex processes messages generated in

    S-1 and send messages to be processed in S+1 and determines to halt.
17. None

18. apache giraph

19. giraph Loose implementation of Pregel ideas on top of Hadoop

    M/R coming from yahoo

20. apache giraph http://incubator.apache.org/giraph/

21. giraph avoid overhead of classic M/R process but reuse existing

    infrastructure

22. giraph simple map jobs in master worker setup. coordination via

    zookeeper. messaging via own RPC protocol. in memory processing. custom input and output formats.

23. current status version 0.1 released compatible with a multitude of

    hadoop versions (we use CDH3 at work) still lots of things to do, join the fun!

24. the APIs the APIs

25. Vertex-API /** *@param <I> vertex id * @param <V> vertex

    data * @param <E> edge data * @param <M> message data */ class BasicVertex<I extends WritableComparable, V extends Writable, E extends Writable, M extends Writable> void compute(Iterator<M> msgIterator); void sendMsg(I id, M msg); void voteToHalt();

26. Shortest path example https://cwiki.apache.org/confl uence/display/GIRAPH/Shorte st+Paths+Example

27. v2 v5 v4 v7 v3 v8 v6 v1 v9 v8

    v10 simple graph

28. private boolean isSource() { return (getVertexId().get() == getContext().getConfiguration().getLong(SOURCE_ID, SOURCE_ID_DEFAULT)); }

    @Override public void compute(Iterator<DoubleWritable> msgIterator) { if (getSuperstep() == 0) { setVertexValue(new DoubleWritable(Double.MAX_VALUE)); } double minDist = isSource() ? 0d : Double.MAX_VALUE; while (msgIterator.hasNext()) { minDist = Math.min(minDist, msgIterator.next().get()); } if (minDist < getVertexValue().get()) { setVertexValue(new DoubleWritable(minDist)); for (Edge<LongWritable, FloatWritable> edge : getOutEdgeMap().values()) { sendMsg(edge.getDestVertexId(), new DoubleWritable(minDist + edge.getEdgeValue().get())); } } voteToHalt(); }

29. GiraphJob job = new GiraphJob(getConf(), getClass().getName()); job.setVertexClass(SimpleShortestPathVertex.class); job.setVertexInputFormatClass(SimpleShortestPathsVertexInputFormat.class); job.setVertexOutputFormatClass( SimpleShortestPathsVertexOutputFormat.class);

    FileInputFormat.addInputPath(job, new Path(„/foo/bar/baz“)); FileOutputFormat.setOutputPath(job, new Path(„/foo/bar/quux“)); job.getConfiguration().setLong(SimpleShortestPathsVertex.SOURCE_ID, Long.parseLong(argArray[2])); job.setWorkerConfiguration(minWorkers, maxWorkers), 100.0f); GiraphJob

30. see also http://incubator.apache.org/giraph/ https://cwiki.apache.org/confluence/displ ay/GIRAPH/Shortest+Paths+Example http://googleresearch.blogspot.com/2009/ 06/large-scale-graph-computing-at- google.html

31. Thanks! Questions?