The task id is readily available, if you override the configure method.
The MapReduceBase class in the Pro Hadoop Book examples does this and makes
the taskId available as a class field.
On Thu, Jun 18, 2009 at 7:33 AM, Mark Desnoyer <mdesno...@gmail.com> wrote:
> Thanks! I'll try that.
>
> -Mark
>
> On Thu, Jun 18, 2009 at 10:27 AM, Jingkei Ly <jingkei...@detica.com>
> wrote:
>
> > I think you can use job.getInt("mapred.task.partition",-1) to get the
> > mapper ID, which should be the same for the mapper across task reruns.
> >
> > -----Original Message-----
> > From: Piotr Praczyk [mailto:piotr.prac...@gmail.com]
> > Sent: 18 June 2009 15:19
> > To: core-user@hadoop.apache.org
> > Subject: Re: Getting Task ID inside a Mapper
> >
> > Hi
> > Why don't you provide a seed of random generator generated outside the
> > task
> > ? Then when the task fails, you can provide the same value stored
> > somewhere
> > outside.
> > You could use the task configuration to do so.
> >
> > I don't know anything about obtaining the task ID from within.
> >
> >
> > regards
> > Piotr
> >
> > 2009/6/18 Mark Desnoyer <mdesno...@gmail.com>
> >
> > > Hi,
> > >
> > > I was wondering if it's possible to get a hold of the task id inside a
> > > mapper? I cant' seem to find a way by trolling through the API
> > reference.
> > > I'm trying to implement a Map Reduce version of Latent Dirichlet
> > Allocation
> > > and I need to be able to initialize a random number generator in a
> > task
> > > specific way so that if the task fails and is rerun elsewhere, the
> > results
> > > are the same. Thanks in advance.
> > >
> > > Cheers,
> > > Mark Desnoyer
> > >
> >
> >
> >
> > This message should be regarded as confidential. If you have received
> this
> > email in error please notify the sender and destroy it immediately.
> > Statements of intent shall only become binding when confirmed in hard
> copy
> > by an authorised signatory. The contents of this email may relate to
> > dealings with other companies within the Detica Group plc group of
> > companies.
> >
> > Detica Limited is registered in England under No: 1337451.
> >
> > Registered offices: Surrey Research Park, Guildford, Surrey, GU2 7YP,
> > England.
> >
> >
> >
>
--
Pro Hadoop, a book to guide you from beginner to hadoop mastery,
http://www.amazon.com/dp/1430219424?tag=jewlerymall
www.prohadoopbook.com a community for Hadoop Professionals
