I don think reduce jobs can start unless all maps are over because the values are accumulated at the end of map stage only. are you using the default scheduler?
On Tue, Dec 21, 2010 at 7:23 AM, li ping <li.j...@gmail.com> wrote: > I think the reduce can be started before all of the map finished. > See the configration item in mapred-site.xml > > <property> > <name>mapred.reduce.slowstart.completed.maps</name> > <value>0.05</value> > <description>Fraction of the number of maps in the job which should be > complete before reduces are scheduled for the job. > </description> > </property> > > Correct me, if I'm wrong. > > On Tue, Dec 21, 2010 at 4:18 AM, Harsh J <qwertyman...@gmail.com> wrote: > >> Hi, >> >> On Tue, Dec 21, 2010 at 12:03 AM, Pedro Costa <psdc1...@gmail.com> wrote: >> > 1 - A reduce task should start only when a map task ends ? >> Only when all map()s finish, the reduce() is called, yes. >> > >> > -- >> > Pedro >> > >> >> >> >> -- >> Harsh J >> www.harshj.com >> > > > > -- > -----李平 > -- Regards, R.V.
