TaskTracker will tell JobTracker how many free slots it has through heartbeat. And JobTracker will choose the best tasktracker with the consideration of data locality.
On Thu, Oct 28, 2010 at 2:52 PM, Zhenhua Guo <jen...@gmail.com> wrote: > Hi, all > I wonder how Hadoop schedules mappers and reducers (e.g. consider > load balancing, affinity to data?). For example, how to decide on > which nodes mappers and reducers are to be executed and when. > Thanks! > > Gerald > -- Best Regards Jeff Zhang
