Hey Michael,
I think you're misreading things. There are indeed 17 launched map
tasks, which are run one at a time, not in parallel.
Brian
On Dec 27, 2008, at 9:24 AM, Michael wrote:
Hi everyone:
How do I control the number of threads per mapreduce job. I am using
bin/hadoop jar wordcount to run jobs and even though I have found
these
settings in hadoop-default.xml and changed the values to 1:
<name>mapred.tasktracker.map.tasks.maximum</name>
<name>mapred.tasktracker.reduce.tasks.maximum</name>
The output of the job seems to indicate otherwise.
08/12/26 18:21:12 INFO mapred.JobClient: Job Counters
08/12/26 18:21:12 INFO mapred.JobClient: Launched reduce tasks=1
08/12/26 18:21:12 INFO mapred.JobClient: Rack-local map tasks=12
08/12/26 18:21:12 INFO mapred.JobClient: Launched map tasks=17
08/12/26 18:21:12 INFO mapred.JobClient: Data-local map tasks=4
I have 2 servers running the mapreduce process and the datanode
process.
Thanks,
Michael
