[ http://issues.apache.org/jira/browse/HADOOP-229?page=comments#action_12412420 ]
Milind Bhandarkar commented on HADOOP-229: ------------------------------------------ Number of maps is now computed as follows: numMaps = max(1, min(numFiles, numNodes*10, totalBytes/256MB, 10000)). Plus added reporting status for every file (or every 32MB - approx 10 seconds) so that tasks dont timeout while copying huge files. This fix is part of the patch attached to hadoop-220. > hadoop cp should generate a better number of map tasks > ------------------------------------------------------ > > Key: HADOOP-229 > URL: http://issues.apache.org/jira/browse/HADOOP-229 > Project: Hadoop > Type: Bug > Components: fs > Reporter: Yoram Arnon > Assignee: Milind Bhandarkar > Priority: Minor > > hadoop cp currently assigns 10 files to copy per map task. > in case of a small number of large files on a large cluster (say 300 files of > 30GB each on a 300 node cluster), this results in long execution times. > better would be to assign files per task such that the entire cluster is > utilized: one file per map, with a cap of 10000 maps total, so as not to over > burden the job tracker. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
