Hello Karen, Did you restart the TaskTracker after making the maximum change (it sounds like it was already set for you)? That mapred.tasktracker.map.tasks.maximum property sets the maximum number of map tasks which may be run on a given machine (TaskTracker). There is also a property for setting the number of tasks actually used in a given job (mapred.map.tasks). Which version of Hadoop are you running? Here is some good information: http://wiki.apache.org/hadoop/HowManyMapsAndReduces
________________________________ Ronnie Dove OceanSync Hadoop Management http://www.oceansync.com ________________________________ From: Keren Ouaknine <ker...@gmail.com> To: mapreduce-user@hadoop.apache.org Sent: Monday, November 28, 2011 10:14 PM Subject: Re: #number of mappers Thanks Harsh, the property in already set to one on all the nodes (see below). What do you reckon? <property> <name>mapred.tasktracker.map.tasks.maximum</name> <value>1</value> <description>The maximum number of map tasks that will be run simultaneously by a task tracker.</description> </property> <name>mapred.tasktracker.reduce.tasks.maximum</name> <value>1</value> <description>The maximum number of reduce tasks that will be run simultaneously by a task tracker.</description> </property> </configuration> On Thu, Nov 24, 2011 at 10:45 PM, Harsh J <ha...@cloudera.com> wrote: Keren, > > >What was your configured property at the TaskTrackers? The right property >is mapred.tasktracker.{map,reduce}.tasks.maximum, and applies to each >TaskTracker individually (so all your TT mapred-site.xml need to carry that >property to limit their slots). > > >On 25-Nov-2011, at 8:45 AM, Keren Ouaknine wrote: > >Hello, >> >>I configured mapred-site.xml with one mapper, still the web ui shows: >>Map shows capacity 40 = 2 x #machines. I was expecting it to be 20. >>Any idea? >> >>Thanks, >>Keren >> >> >> >>Running Map Tasks >>Running Reduce Tasks >>Total Submissions >>Nodes >>Occupied Map Slots >>Occupied Reduce Slots >>Reserved Map Slots >>Reserved Reduce Slots >>Map Task Capacity >>Reduce Task Capacity >>Avg. Tasks/Node >>Blacklisted Nodes >>Graylisted Nodes >>Excluded Nodes >>34 20 7 20 34 20 0 0 40 20 3.00 0 0 0 >>-- >> >>Keren OuaknineCell: +972 54 2565404 >>Web: www.kereno.com >> >> >> > -- Keren OuaknineCell: +972 54 2565404 Web: www.kereno.com 25-Nov-2011, at 8:45 AM, Keren Ouaknine wrote: Hello, > >I configured mapred-site.xml with one mapper, still the web ui shows: >Map shows capacity 40 = 2 x #machines. I was expecting it to be 20. >Any idea? > >Thanks, >Keren > > > >Running Map Tasks >Running Reduce Tasks >Total Submissions >Nodes >Occupied Map Slots >Occupied Reduce Slots >Reserved Map Slots >Reserved Reduce Slots >Map Task Capacity >Reduce Task Capacity >Avg. Tasks/Node >Blacklisted Nodes >Graylisted Nodes >Excluded Nodes >34 20 7 20 34 20 0 0 40 20 3.00 0 0 0 >-- > >Keren OuaknineCell: +972 54 2565404 >Web: www.kereno.com > > > -- Keren OuaknineCell: +972 54 2565404 Web: www.kereno.com
