1. If you use org.apache.log4j.Logger, you would be able to observe log messages through http://jobtracker:50060/tasklog?taskid=(attempt_201006052003_0003_m_000001_0&start=-8193) private final static Logger LOG = Logger.getLogger(AbstractRepMapper.class);
2. After you submitted job to hadoop cluster, you need to use "hadoop job -kill <job_id>" See http://support.cc.gatech.edu/facilities/instructional-labs/how-to-submit-and-manage-hadoop-jobs On Sat, Jun 5, 2010 at 7:00 PM, Kevin Tse <[email protected]> wrote: > Hello, > I have successfully run Hadoop on a cluster of 3 nodes on RedHat linux, I > have several questions to ask. > > 1. When I submit an MR job using "hadoop jar mr-job.jar", it starts > printing > out log messages to the stdout, how do I make it run in the > background?("hadoop jar mr-job.jar > log &" does not work). If it can be > put > in the background, where do I find those log messages that it used to print > to the stdout? > 2. While the MR job is being executed, will the MR job process be > affected/killed if I press "Ctrl-c"? it seems not since I can see the > tasktracker is still running, but I am not sure. > 3. While the MR job is being executed, if I stop one of the > tasktrackers/nodes in the cluster using hadoop-daemon.sh, will the result > of > the maps and reduces semi-completed by that tasktracker/node be submitted > to > the namenode to be merged with the results completed by other tasktrackers? > Is it possible to restart a tasktracker at a point where it was stopped? > > Thank you in advance. > - Kevin Tse >
