Are you writing your own application i.e. custom ApplicationMaster?
You need to pass ResourceRequest (RR) with a valid hostname alongwith
(optionally) RR with rack and also a mandatory RR with * as the resource-name.
Arun
On Jan 4, 2012, at 8:04 PM, raghavendhra rahul wrote:
> Hi,
>
> I tried to set the client node for launching the container within the
> application master.
> I have set the parameter as
> request.setHostName("client");
> but the containers are not launched in the destined host.Instead the loop
> goes on continuously.
> 2012-01-04 15:11:48,535 INFO appmaster.ApplicationMaster
> (ApplicationMaster.java:run(204)) - Current application state: loop=95,
> appDone=false, total=2, requested=2, completed=0, failed=0, currentAllocated=0
>
> On Wed, Jan 4, 2012 at 11:24 PM, Robert Evans <[email protected]> wrote:
> Ann,
>
> A container more or less corresponds to a task in MRV1. There is one
> exception to this, as the ApplicationMaster also runs in a container. The
> ApplicationMaster will request new containers for each mapper or reducer task
> that it wants to launch. There is separate code from the container that will
> serve up the intermediate mapper output and is run as part of the NodeManager
> (Similar to the TaskTracker from before). When the ApplicationMaster
> requests a container it also includes with it a hint as to where it would
> like the container placed. In fact it actually makes three request one for
> the exact node, one for the rack the node is on, and one that is generic and
> could be anywhere. The scheduler will try to honor those requests in the
> same order so data locality is still considered and generally honored. Yes
> there is the possibility of back and forth to get a container, but the
> ApplicationMaster generally will try to use all of the containers that it is
> given, even if they are not optimal.
>
> --Bobby Evans
>
>
> On 1/4/12 10:23 AM, "Ann Pal" <[email protected]> wrote:
>
> Hi,
> I am trying to understand more about Hadoop Next Gen Map Reduce and had the
> following questions based on the following post:
>
> http://developer.yahoo.com/blogs/hadoop/posts/2011/03/mapreduce-nextgen-scheduler/
>
> [1] How does application decide how many containers it needs? The containers
> are used to store the intermediate result at the map nodes?
>
> [2] During resource allocation, if the resource manager has no mapping
> between map tasks to resources allocated, how can it properly allocate the
> right resources. It might end up allocating resources on a node, which does
> not have data for the map task, and hence is not optimal. In this case the
> Application Master will have to reject it and request again . There could be
> considerable back- and- forth between application master and resource manager
> before it could converge. Is this right?
>
> Thanks!
>
>
