Home | About | Sematext search-lucene.com search-hadoop.com
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB
 Search Hadoop and all its subprojects:

Switch to Threaded View
MapReduce >> mail # user >> RE: a question on MapReduce


Copy link to this message
-
Re: a question on MapReduce
Hello Andy,

  Reduce phase starts only once the Map phase is 100% complete. The reduce
progress you see actually signifies other intermediate processes like
shuffle and sort. Don't get confused with it like I did initially :)

Regards,
    Mohammad Tariq

On Mon, Nov 19, 2012 at 8:07 PM, Kartashov, Andy <[EMAIL PROTECTED]>wrote:

>  Guys,
>
>
>
> Sometimes when I run my MR job I see that Reduce tasks kick in as early as
> when Map task reached only about 20%. How can the MR be possibly so sure
> and start running Reduce at this point? What if a Mapper  produce more keys
> that Reduce function already finished with?
>
>
>
> Andy Kartashov
>
> *MPAC*
>
> IT Architecture, Co-op
>
> 1340 Pickering Parkway, Pickering, L1V 0C4
>
> ( Phone : (905) 837 6269
>
> ( Mobile: (416) 722 1787
>
> *[EMAIL PROTECTED]*
>
>
>  NOTICE: This e-mail message and any attachments are confidential, subject
> to copyright and may be privileged. Any unauthorized use, copying or
> disclosure is prohibited. If you are not the intended recipient, please
> delete and contact the sender immediately. Please consider the environment
> before printing this e-mail. AVIS : le présent courriel et toute pièce
> jointe qui l'accompagne sont confidentiels, protégés par le droit d'auteur
> et peuvent être couverts par le secret professionnel. Toute utilisation,
> copie ou divulgation non autorisée est interdite. Si vous n'êtes pas le
> destinataire prévu de ce courriel, supprimez-le et contactez immédiatement
> l'expéditeur. Veuillez penser à l'environnement avant d'imprimer le présent
> courriel
>
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB