Hadoop > common-user > May 2006

Hello everybody, I'll ask my first question on this forum and hopefully start building more and more understanding of hadoop so that we can eventually contribute actively. In the meanwhile, I have a ...

I am trying to read a MapFile inside mapper and reducer implementations. So far the only way I have found to do it is by opening a new reader for each map and reduce call. Is anybody doing something ...

I am trying to understand what happens during the time duration when Map task got finished and reduce task starts executing. I have 2 machines with 4 process + 4 Gigs on each with NFS (not dfs) to ...

Hi all, I am trying to process several gigs of zipped text files from a directory. If I unzip them the size increase atleast 4 times and potentially I can run out of disk space. Has anyone tried to ...

Hi! I am new to hadoop as well as cygwin, and as far as I know, you need to use cygwin in order to use hadoop on win. Unfortunately I'm not allowed to switch to linux or even use a linux machine to ...

I am seeing a lot of these kind of messages in the namenode log file. Can somebody point me in the right direction as to why this might be happening? DIR* FSDirectory.mkdirs: failed to create ...

Hi, I am looking for a distributed file system for large numbers of small files (a few KB each). Maybe the files would be rows in HDFS. But my access patterns are different from MapRed-style jobs: ...

Hi all, Many reduce tasks seems stall for a long time on "reduce copy" status especially they all wait on one map task transfer example task_0048_m_000120_0@node 10:50040. So the status is like ...

How would I set the map output value class to be different from the reduce output value class. I am trying the code below but it doesn't seem to work. It throws an error saying WordWeights is not ...

Am I right in understanding that MapReduce tasks are not pushed to TaskTrackers by the JobTracker, but that the TaskTrackers continually poll the JobTracker for a Task to run and the JobTracker then ...

I am trying to run 8 map tasks with 2 reduce on 3 machines. Each task runs on a 6 MB text file and 500 such files. The monitoring page shows very few number of Map tasks running than intended. ...