Thanks Charith, but my main question still remains, even with the examples that
comes with Giraph, such as simple shortest path computation example, the
System.out.println or the Log.Debug (or I also tried Log.Info) they all do not
print out customer messages that I write in the compute method.
For example, I modified the class SimpleShortestPathsComputation to use println
instead of Log.Debug, here is the compute method (I’ve highlighted the print
statments):
@Override
public void compute(
Vertex<LongWritable, DoubleWritable, FloatWritable> vertex,
Iterable<DoubleWritable> messages) throws IOException {
if (getSuperstep() == 0) {
vertex.setValue(new DoubleWritable(Double.MAX_VALUE));
}
double minDist = isSource(vertex) ? 0d : Double.MAX_VALUE;
for (DoubleWritable message : messages) {
minDist = Math.min(minDist, message.get());
}
System.out.println("Vertex " + vertex.getId() + " got minDist = " + minDist
+ " vertex value = " + vertex.getValue());
if (minDist < vertex.getValue().get()) {
vertex.setValue(new DoubleWritable(minDist));
for (Edge<LongWritable, FloatWritable> edge : vertex.getEdges())
{
double distance = minDist + edge.getValue().get();
System.out.println("Vertex " + vertex.getId() + " sent to " +
edge.getTargetVertexId() + " = " + distance);
sendMessage(edge.getTargetVertexId(), new DoubleWritable(distance));
}
}
vertex.voteToHalt();
}
Still the statements for println do not write these messages out, are they
supposed to be somewhere else or are they are not written?
I also tried with log.info, but again these statements were not written, I
prefer to use println.
Thanks,
Tamer
From: Charith Wickramarachchi [mailto:[email protected]]
Sent: Thursday, October 02, 2014 4:53 PM
To: user
Subject: Re: How to Write to HDFS?
Hi Tamer,
The reason you see this behavior is IntIntNullTextInputFormat sets the value of
the vertex as same as the vertex id when creating a vertex. Since you do not
change the value vertex id will be written to the output as the vertex value.
See the class
org.apache.giraph.io.formats.IntIntNullTextInputFormat.IntIntNullVertexReader
and you will understand.
Hope this helps.
Thanks,
Charith
On Thu, Oct 2, 2014 at 1:35 PM, Tamer Yousef
<[email protected]<mailto:[email protected]>> wrote:
Hello All!
I’m learning Giraph and trying few things, but I fail to write out output to
hdfs. I created my own .java file, and I placed it in the folder
${GIRAPH_HOME}//giraph-examples/src/main/java/org/apache/giraph/examples/ then
I ran the mvn compile to get a jar file that includes my class. The function is
doing nothing other than trying to:
1- Write using the stdout
2- Write using log4j
The program runs and it creates an output directory in hdfs as I specify in the
command below, but the output file does not reflect what the program should
write out.
Here is the output I get in the output file in HDFS (the vertices I have are
very similar):
6 6
5 5
13 13
12 12
8 8
7 7
2 2
15 15
9 9
16 16
10 10
1 1
3 3
14 14
11 11
4 4
Even if I completely comment out the code in the compute class, I still get the
output above (with keeping the voteToHalt method).
I execute the code using the command:
hadoop jar
$GIRAPH_HOME/giraph-examples/target/giraph-examples-1.1.0-SNAPSHOT-for-hadoop-1.2.1-jar-with-dependencies.jar
org.apache.giraph.GiraphRunner org.apache.giraph.examples.HelloWorld -vif
org.apache.giraph.io.formats.IntIntNullTextInputFormat -vip /in/graph2.txt -vof
org.apache.giraph.io.formats.IdWithValueTextOutputFormat -op /out5 -w 1
I’m working with Hadoop 1.2.1 and the latest Giraph from the trunk.
and here is my full class:
package org.apache.giraph.examples;
import org.apache.giraph.GiraphRunner;
import org.apache.hadoop.util.ToolRunner;
import org.apache.giraph.graph.BasicComputation;
import org.apache.giraph.conf.LongConfOption;
import org.apache.giraph.edge.Edge;
import org.apache.giraph.graph.Vertex;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.FloatWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.log4j.Logger;
import java.io.IOException;
@Algorithm(
name = "Hellow",
description = "test class"
)
public class HelloWorld extends
BasicComputation<IntWritable, IntWritable,
NullWritable, NullWritable> {
@Override
public void compute(Vertex<IntWritable,
IntWritable, NullWritable>
vertex,
Iterable<NullWritable>
messages) {
System.out.println("Hello world from print
ln");
LOG.info("Hello world from log info");
vertex.voteToHalt();
}
public static void main(String[] args) throws Exception
{
//log4j.logger.org.apache.hadoop = DEBUG;
System.exit(ToolRunner.run(new
GiraphRunner(), args));
}
/** Class logger */
private static final Logger LOG =
Logger.getLogger(SimpleShortestPathsComputation.class);
}
Any ideas?
Thanks!
--
Charith Dhanushka Wickramaarachchi
Tel +1 213 447 4253
Web http://apache.org/~charith<http://www-scf.usc.edu/~cwickram/>
Blog http://charith.wickramaarachchi.org/<http://charithwiki.blogspot.com/>
Twitter @charithwiki<https://twitter.com/charithwiki>
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