Sorry for the typo, the property name is mapred.max.split.size Also just for changing the number of map tasks you don't need to modify the hdfs block size.
On Tue, Oct 2, 2012 at 10:31 PM, Bejoy Ks <[email protected]> wrote: > Hi > > You need to alter the value of mapred.max.split size to a value larger > than your block size to have less number of map tasks than the default. > > > On Tue, Oct 2, 2012 at 10:04 PM, Shing Hing Man <[email protected]> wrote: > >> >> >> >> I am running Hadoop 1.0.3 in Pseudo distributed mode. >> When I submit a map/reduce job to process a file of size about 16 GB, >> in job.xml, I have the following >> >> >> mapred.map.tasks =242 >> mapred.min.split.size =0 >> dfs.block.size = 67108864 >> >> >> I would like to reduce mapred.map.tasks to see if it improves >> performance. >> I have tried doubling the size of dfs.block.size. But >> the mapred.map.tasks remains unchanged. >> Is there a way to reduce mapred.map.tasks ? >> >> >> Thanks in advance for any assistance ! >> Shing >> >> >
