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. HTH, +Vinod Kumar Vavilapalli Hortonworks Inc. http://hortonworks.com/ 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 >
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