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From Hemanth Yamijala <yhema...@gmail.com>
Subject Re: delay the execution of reducers
Date Thu, 02 Dec 2010 09:29:45 GMT
> Changing the parameter for a specific job works better for me.
> But I was asking in general in which configuration file(s) should I change
> the value of the parameters.
> For parameters in hdfs-site.xml, I should changes the configuration file in
> each machine. But for parameters in mapred-site.xml, it seems enough to
> change the configuration file in the machine where the job is launched

Ideally, if you knew which processes need to read the configuration
value, you can set it in the configuration files on nodes running
those processes. For instance, you knew a parameter is only required
on the NameNode, you can set it in the hdfs-site.xml on the NameNode
and so on. If in doubt though, it almost always helps to set the same
value in the configuration files on all nodes.


> Thanks,
> Da
> On 11/29/2010 01:31 PM, Arun C Murthy wrote:
>> Just set it for you  job.
>> In your launching program do something like:
>> jobConf.setFloat("mapred.reduce.slowstart.completed.maps", 0.5);
>> On Nov 29, 2010, at 9:46 AM, Da Zheng wrote:
>>> On 11/29/2010 05:42 AM, Chandraprakash Bhagtani wrote:
>>>> you can see whether your property is in effect by looking at the
>>>> following
>>>> URL
>>>> http://<jobtracker-host>:50030/jobconf.jsp?jobid=<job-id>
>>>> replace<jobtracker-host>  with your jobtracker ip and<job-id>
 with the
>>>> running job
>>>> have you restarted mapreduce after changing mapred-site.xml?
>>> It shows me the value is still 0.05. I am a little confused. Since
>>> hadoop in each machine has configuration files, which configuration
>>> files should I change? For mapred-site.xml, I only need to change the
>>> one in the master node? (I always start my MapReduce program from the
>>> master node). What about other configuration files such as core-site.xml
>>> and hdfs-site.xml? I guess I have to change them on all machines in the
>>> cluster.
>>> Thanks,
>>> Da

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