How to ensure that only one worker runs per node

Hi everyone, Is there a good way (a configuration I'm guessing) to prevent more than one worker from running per node? I saw in this thread https://www.mail-archive.com/user@giraph.apache.org/msg01580.html to use mapred.tasktracker.map.tasks.maximum=1, but that doesn't seem to be working. Thanks

Re: How to ensure that only one worker runs per node

As I understand it, 1) set the variable to 1 as you say, and 2) specify the number of workers to the number of nodes - 1 (for the master). When you run a job you can look at the 'map' link on the tasktracker ui to see all the workers plus master. On Thu, Oct 30, 2014 at 7:11 AM, Matthew Saltz

Re: How to ensure that only one worker runs per node

Thanks Matthew. I just realized in searching a bit more that the variable has to be set in the mapred-site.xml configuration file with hadoop 0.20.203, otherwise it doesn't affect anything. I was setting it in the command line. I've already been setting the number of workers the way you