[ https://issues.apache.org/jira/browse/MAPREDUCE-1901?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Junjie Liang updated MAPREDUCE-1901: ------------------------------------ Attachment: 1901.PATCH Patch for version 20.2 ================= Set "mapred.cache.shared.enabled" to "true" to enable cache files to be shared across jobs. > Jobs should not submit the same jar files over and over again > ------------------------------------------------------------- > > Key: MAPREDUCE-1901 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1901 > Project: Hadoop Map/Reduce > Issue Type: Improvement > Reporter: Joydeep Sen Sarma > Attachments: 1901.PATCH > > > Currently each Hadoop job uploads the required resources > (jars/files/archives) to a new location in HDFS. Map-reduce nodes involved in > executing this job would then download these resources into local disk. > In an environment where most of the users are using a standard set of jars > and files (because they are using a framework like Hive/Pig) - the same jars > keep getting uploaded and downloaded repeatedly. The overhead of this > protocol (primarily in terms of end-user latency) is significant when: > - the jobs are small (and conversantly - large in number) > - Namenode is under load (meaning hdfs latencies are high and made worse, in > part, by this protocol) > Hadoop should provide a way for jobs in a cooperative environment to not > submit the same files over and again. Identifying and caching execution > resources by a content signature (md5/sha) would be a good alternative to > have available. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.