You could start off doing the following:

- Check the box on which the task is running, is it under heavy load ? Is
there high amount of I/O wait ?
- You could check the task logs and see if they say anything about what is
going wrong ?
- Did the task get pre-empted to other task trackers ? If yes, is it stuck
at the same spot on those ?
- What kind of work are you doing in the mapper ? Just reading from HDFS
and compute something or reading/writing from HBase ?

Thanks,
Viral

On Thu, Feb 28, 2013 at 12:06 PM, Patai Sangbutsarakum <
[EMAIL PROTECTED]> wrote:

> Hadoopers!!
>
> Need input from you guys,
> i am looking at a critical job in production. it stucks at 99.99% in
> map phrase for much longer than it used to be..
>
> what to do to debug what is going on with those map why it is not pass
> through
> even though tasks and task attempts saying 100% progress but there is
> not finish time...
>
> Please suggest
> Patai
>