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MapReduce, mail # user - Re: distributed cache

Harsh J 2012-12-26, 10:21
Lin Ma 2012-12-26, 10:43
Harsh J 2012-12-26, 11:48
Lin Ma 2012-12-22, 12:03
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Re: distributed cache
Kai Voigt 2012-12-22, 12:44

Am 22.12.2012 um 13:03 schrieb Lin Ma <[EMAIL PROTECTED]>:

> I want to confirm when on each task node either mapper or reducer access distributed cache file, it resides on disk, not resides in memory. Just want to make sure distributed cache file does not fully loaded into memory which compete memory consumption with mapper/reducer tasks. Is that correct?
Yes, you are correct. The JobTracker will put files for the distributed cache into HDFS with a higher replication count (10 by default). Whenever a TaskTracker needs those files for a task it is launching locally, it will fetch a copy to its local disk. So it won't need to do this again for future tasks on this node. After a job is done, all local copies and the HDFS copies of files in the distributed cache are cleaned up.


Kai Voigt
Lin Ma 2012-12-22, 12:46
Kai Voigt 2012-12-22, 12:51
Lin Ma 2012-12-22, 13:24
Harsh J 2012-12-26, 08:51
Ted Yu 2013-07-09, 22:07