hadoop-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Vinod Kumar Vavilapalli <vino...@hortonworks.com>
Subject Re: Questions with regard to scheduling of map and reduce tasks
Date Fri, 31 Aug 2012 22:59:39 GMT

You don't need to touch the code related protocol-buffer records at all as there are java-native
interfaces for everything, for e.g. - org.apache.hadoop.yarn.api.AMRMProtocol.

Regarding your question - The JobClient first obtains the locations of DFS blocks via the
InputFormat.getSplits() and uploads the accumulated information into a split file, see Job.submitInternal()
->  JobSubmitter.writeSplits() ->  ...

The MR AM then downloads and reads the split file and reconstructs the splits-information
and creates TaskAttempts(TAs) which then use it request containers. See MRAppMaster code:
JobImpl.InitTransition for how TAs are created with host information.


+Vinod Kumar Vavilapalli
Hortonworks Inc.

On Aug 31, 2012, at 4:17 AM, Vasco Visser wrote:

> Thanks again for the reply, it is becoming clear.
> While on the subject of going over the code, do you know by any chance
> where the piece of code is that creates resource requests according to
> locations of HDFS blocks? I am looking for that, but the protocol
> buffer stuff makes it difficult for me to understand what is going on.
> regards, Vasco

View raw message