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MapReduce >> mail # user >> Distributing the code to multiple nodes

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RE: Distributing the code to multiple nodes

Could this be related to the scheduler you are using and its settings?.


On lab environments when running a single type of job I often use
FairScheduler (the YARN default in 2.2.0 is CapacityScheduler) and it does a
good job distributing the load.


You could give that a try


I think just changing yarn-site.xml  as follows could demonstrate this
theory (note that  how the jobs are scheduled depend on resources such as
memory on the nodes and you would need to setup yarn-site.xml accordingly).











From: Ashish Jain [mailto:[EMAIL PROTECTED]]
Sent: Thursday, January 09, 2014 6:46 AM
Subject: Re: Distributing the code to multiple nodes


Another point to add here is the host which has everything
running including a slave datanode. Data was also distributed this host as
well as the jar file. Following are running on

7966 DataNode
8480 NodeManager
8353 ResourceManager
8141 SecondaryNameNode
7834 NameNode


On Thu, Jan 9, 2014 at 6:12 PM, Ashish Jain <[EMAIL PROTECTED]> wrote:

Logs were updated only when I copied the data. After copying the data there
has been no updates on the log files.


On Thu, Jan 9, 2014 at 5:08 PM, Chris Mawata <[EMAIL PROTECTED]> wrote:

Do the logs on the three nodes contain anything interesting?

On Jan 9, 2014 3:47 AM, "Ashish Jain" <[EMAIL PROTECTED]> wrote:

Here is the block info for the record I distributed. As can be seen only has all the data and this is the node which is serving all the
request. Replicas are available with 209 as well as 210

1073741857:    View Block Info    View Block Info
1073741858:    View Block Info    View Block Info
1073741859:    View Block Info    View Block Info
1073741860:    View Block Info    View Block Info
1073741861:    View Block Info    View Block Info
1073741862:    View Block Info    View Block Info
1073741863:    View Block Info    View Block Info
1073741864:    View Block Info    View Block Info



On Thu, Jan 9, 2014 at 2:11 PM, Ashish Jain <[EMAIL PROTECTED]> wrote:

Hello Chris,

I have now a cluster with 3 nodes and replication factor being 2. When I
distribute a file I could see that there are replica of data available in
other nodes. However when I run a map reduce job again only one node is
serving all the request :(. Can you or anyone please provide some more



On Wed, Jan 8, 2014 at 7:16 PM, Chris Mawata <[EMAIL PROTECTED]> wrote:

2 nodes and replication factor of 2 results in a replica of each block
present on each node. This would allow the possibility that a single node
would do the work and yet be data local.  It will probably happen if that
single node has the needed capacity.  More nodes than the replication factor
are needed to force distribution of the processing.

On Jan 8, 2014 7:35 AM, "Ashish Jain" <[EMAIL PROTECTED]> wrote:


I am sure that only one node is being used. I just know ran the job again
and could see that CPU usage only for one server going high other server CPU
usage remains constant and hence it means other node is not being used. Can
someone help me to debug this issue?



On Wed, Jan 8, 2014 at 5:04 PM, Ashish Jain <[EMAIL PROTECTED]> wrote:

Hello All,

I have a 2 node hadoop cluster running with a replication factor of 2. I
have a file of size around 1 GB which when copied to HDFS is replicated to
both the nodes. Seeing the block info I can see the file has been subdivided
into 8 parts which means it has been subdivided into 8 blocks each of size
128 MB.  I use this file as input to run the word count program. Some how I
feel only one node is doing all the work and the code is not distributed to
other node. How can I make sure code is distributed to both the nodes? Also
is there a log or GUI which can be used for this?

Please note I am using the latest stable release that is 2.2.0.