> I think mapred.tasktracker.map.tasks.maximum sets the number of map tasks and not slots.
This is incorrect. The property does configure slots. Please also see http://wiki.apache.org/hadoop/HowManyMapsAndReduces and http://wiki.apache.org/hadoop/FAQ#I_see_a_maximum_of_2_maps.2BAC8-reduces_spawned_concurrently_on_each_TaskTracker.2C_how_do_I_increase_that.3F for more. On Wed, Jun 6, 2012 at 9:56 AM, kartheek muthyala <kartheek0...@gmail.com> wrote: > I think mapred.tasktracker.map.tasks.maximum sets the number of map > tasks and not slots. > Keith, so that means per core, if I specify the maximum number of map > tasks it can host, whether all the maps per slot will run parallely or > they execute one after the other?. I understand that maps that are > scheduled on different cores can run parallely. > > Thanks, > Kartheek. > > On Tue, Jun 5, 2012 at 11:05 AM, madhu phatak <phatak....@gmail.com> wrote: >> Hi, >> You can change the no of slots using the following properties in >> mapred-site.xml. >> >> mapred.tasktracker.map.tasks.maximum ( for map slots) >> mapred.tasktracker.reduce.tasks.maximum (for reduce slot) >> >> >> On Tue, Jun 5, 2012 at 3:44 AM, Keith Wiley <kwi...@keithwiley.com> wrote: >>> >>> The number of slots corresponds to the number of cores (e.g., a 10-node >>> cluster consisting of quad-core cpus has 40 cores and therefore 40 slots). >>> The slots can be divided amongst the maps and reduces in a way which >>> integer-divides into the cores of a single machine. So if the nodes are >>> quad-cores you can do 3:1, 2:2, or 1:3. If the nodes are dual-quad-cores >>> (each node has eight cores) you can do 7:1 through 1:7 in any configuration >>> you want..........as per my understanding. Others may pipe in to clarify >>> some minor point I have missed, I'm unsure. >>> >>> On Jun 4, 2012, at 09:06 , kartheek muthyala wrote: >>> >>> > Hello all, >>> > >>> > Can I increase the number of map slots in a machine using some >>> > configuration?. I can find configurations for increasing the number of >>> > maps and reduce tasks that can run, but didn't find anything related >>> > to slots. Is that default decided based on the memory size? >>> > >>> > Thanks, >>> > Kartheek. >>> >>> >>> >>> ________________________________________________________________________________ >>> Keith Wiley kwi...@keithwiley.com keithwiley.com >>> music.keithwiley.com >>> >>> "I do not feel obliged to believe that the same God who has endowed us >>> with >>> sense, reason, and intellect has intended us to forgo their use." >>> -- Galileo Galilei >>> >>> ________________________________________________________________________________ >>> >> >> >> >> -- >> https://github.com/zinnia-phatak-dev/Nectar >> -- Harsh J
