Where are Apache Giraph logs (with log4j) located?

Question

I am currently experimenting with Apache Giraph using the configuration described in the QuickStart Tutorial :

• Ubuntu 12
• Hadoop 0.20
• Giraph Release 1.2

I am running all computation on a single-node local cluster, as described in the QuickStart.

While running the example computations and other custom codes work fine, I am unable to retrieve/locate the logs expected whith log4j logger.

Could you indicate me where these logs are located, either in local system or HDFS ?

Command used to launch Giraph computation :

$HADOOP_HOME/bin/hadoop path/to/giraph/jar org.apache.giraph.GiraphRunner community.RevertedGraphComputation community.JsonLongLongDoubleVertexInputFormat /user/hduser/input/test_graph.txt community.VertexWithLongValueDoubleEdgeTextOutput /user/hduser/output/reverted

Thank you !

Abreviated version of the java code for logging :

//In RevertedGraphComputation class
 private static Logger LOG = Logger.getLogger(RevertedGraphComputation.class);

 //In compute() method
 LOG.info("Vertex "+vertex.getId());