[YARN-1200] Provide a central view for rack topologies

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.1.0-beta
• Component/s: resourcemanager
• Assignee: Unassigned
• Reporter: Harsh J
• Created: 14/Sep/13 04:24
• Updated: 29/Dec/15 10:15
• Resolved: 16/Sep/13 18:22

Description

It appears that with YARN, any AM (such as the MRv2 AM) that tries to do rack-info-based work, will need to resolve racks locally rather than get rack info from YARN directly: https://github.com/apache/hadoop-common/blob/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/RMContainerAllocator.java#L1054 and its use of a simple implementation of https://github.com/apache/hadoop-common/blob/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/RackResolver.java

This is a regression, as we've traditionally only had users maintain rack mappings and its associated script on a single master role node (JobTracker), not at every compute node. Task spawning hosts have never done/needed rack resolution of their own.

It is silly to have to maintain rack configs and their changes on all nodes. We should have the RM host a stable interface service so that there's only a single view of the topology across the cluster, and document for AMs to use that instead.

Issue Links

• duplicates: YARN-435 Make it easier to access cluster topology information in an AM
• is depended upon by: YARN-896 Roll up for long-lived services in YARN