Look on the job tracker web UI is parameter has taken effect (port 50030) It might be in the wrong config file or something
Serge From: Mark Kerzner <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Tuesday, November 13, 2012 5:19 PM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Re: mapred.tasktracker.map.tasks.maximum 1.0.1 On Tue, Nov 13, 2012 at 10:18 AM, Serge Blazhiyevskyy <[email protected]<mailto:[email protected]>> wrote: What hadoop version are we talking about? From: Mark Kerzner <[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>> Reply-To: "[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>" <[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>> Date: Tuesday, November 13, 2012 5:16 PM To: Hadoop User <[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>> Subject: mapred.tasktracker.map.tasks.maximum Hi, I have a cluster with 4 nodes and 32 many cores on each. My default value for the maximum number of mappers per slot is 1: <property> <name>mapred.tasktracker.map.tasks.maximum</name> <!-- see other kb entry about this one. --> <value>1</value> <final>true</final> </property> (which I think is wrong). Howeve, when sizable jobs run, I see 65 mappers working, so it seems that it does create more than 1 mapper per node. Questions: what maximum number of mappers would be appropriate in this situation? Is that the right way to set them? Thank you. Sincerely, Mark
