hadoop-mapreduce-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From rishi pathak <mailmaverick...@gmail.com>
Subject Re: Draining/Decommisioning a tasktracker
Date Mon, 31 Jan 2011 17:21:02 GMT
Hi Koji,
           Thanks for opening feature request. Right now for the purpose
stated earlier
I have upgraded to hadoop to 0.21. , and trying to see if creating
individual leaf level queues for every tasktracker and changing the state of
it to 'stopped' before the expiry of the walltime. Seems like it will work
for now.

P.S. - What credentials are required for commentiong on an issue in Jira

On Mon, Jan 31, 2011 at 10:22 PM, Koji Noguchi <knoguchi@yahoo-inc.com>wrote:

>  Rishi,
>
> > Using exclude list for TT will not help as Koji has already mentioned
> >
> It’ll help a bit in a sense that no more tasks are assigned to that
> TaskTracker once excluded.
>
> As for TT decommissioning and map outputs handling, opened a Jira for
> further discussion.
> https://issues.apache.org/jira/browse/MAPREDUCE-2291
>
> Koji
>
>
>
> On 1/29/11 5:37 AM, "rishi pathak" <mailmaverick666@gmail.com> wrote:
>
> HI,
>     Here is a description of what we are trying to achieve(whether it is
> possible or not is still not cear):
> We have large computing clusters used majorly  for MPI jobs. We use
> PBS/Torque and Maui for resource allocation and scheduling.
> At most times utilization is very high except for very small resource
> pockets of say 16 cores for 2-5 Hrs. We are trying establish feasibility of
> using these small(but fixed sized) resource pockets for nutch crawls. Our
> configuration is:
>
> # Hadoop 0.20.2 (packaged with nutch)
> #Lustre parallel filesystem for data storage
> # No HDFS
>
> We have JT running on one of the login nodes at all times.
> Request for resource (nodes=16, walltime=05 Hrs.) is made using batch
> system and as a part of job TTs are provisioned. The problem is, when a job
> expires, user processes are cleaned up and thus TT gets killed. With that,
> completed and running map/reduce tasks for nutch job are killed and are
> rescheduled. Solution could be as we see it:
>
> 1. As the filesystem is shared(& persistent),  restart tasks on another TT
> and make intermediate task data available. i.e. sort of checkpointing.
> 2. TT draining - based on a speculative time for task completion, TT whose
> walltime is nearing expiry will go into draining mode.i.e. no new tasks will
> be scheduled on that TT.
>
> For '1', it is very far fetched(we are no Hadoop expert)
> '2' seems to be a more sensible approach.
>
> Using exclude list for TT will not help as Koji has already mentioned
> We looked into capacity scheduler but did'nt find any pointers. Phil, what
> version of hadoop
> have these hooks in scheduler.
>
> On Sat, Jan 29, 2011 at 3:34 AM, phil young <phil.wills.young@gmail.com>
> wrote:
>
> There are some hooks available in the schedulers that could be useful also.
> I think they were expected to be used to allow you to schedule tasks based
> on load average on the host, but I'd expect you can customize them for your
> purpose.
>
>
> On Fri, Jan 28, 2011 at 6:46 AM, Harsh J <qwertymaniac@gmail.com> wrote:
>
> > Moving discussion to the MapReduce-User list:
> > mapreduce-user@hadoop.apache.org
> >
> > Reply inline:
> >
> > On Fri, Jan 28, 2011 at 2:39 PM, rishi pathak <mailmaverick666@gmail.com
> >
> > wrote:
> > > Hi,
> > >        Is there a way to drain a tasktracker. What we require is not to
> > > schedule any more map/red tasks onto a tasktracker(mark it offline) but
> > > still the running tasks should not be affected.
> >
> > You could simply shut the TT down. MapReduce was designed with faults
> > in mind and thus tasks that are running on a particular TaskTracker
> > can be re-run elsewhere if they failed. Is this not usable in your
> > case?
> >
> > --
> > Harsh J
> > www.harshj.com <http://www.harshj.com>
> >
>
>
>
>


-- 
---
Rishi Pathak
National PARAM Supercomputing Facility
C-DAC, Pune, India

Mime
View raw message