To speed up the overall map operation time, the last few map tasks are sent to multiple machines. The machine that finishes first wins and that block is passed onto the reduce phase while the other map tasks are killed and their results ignored.
-Daniel On Wed, Jul 16, 2008 at 9:47 AM, Amar Kamat <[EMAIL PROTECTED]> wrote: > I have seen the opposite case where the maps are shown as 100% done while > there are still some maps running. I have seen this on trunk and there were > some failed/killed tasks. > Amar > Andreas Kostyrka wrote: >> >> On Wednesday 09 July 2008 05:56:28 Amar Kamat wrote: >> >>> >>> Andreas Kostyrka wrote: >>> >>>> >>>> See attached screenshot, wonder how that could happen? >>>> >>> >>> What Hadoop version are you using? Is this reproducible? Is it possible >>> to get the JT logs? >>> >> >> Hadoop 0.17.0 >> >> Reproducible: As such no. I did notice that restarting a tasktracker can >> lower the mapper rate, but this was not the case here. >> >> JT logs? >> >> Andreas >> > >
