[
https://issues.apache.org/jira/browse/MAPREDUCE-6514?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Wangda Tan updated MAPREDUCE-6514:
----------------------------------
Target Version/s: 2.6.4, 2.8.0, 2.7.3 (was: 2.8.0)
> Job hangs as ask is not updated after ramping down of all reducers
> ------------------------------------------------------------------
>
> Key: MAPREDUCE-6514
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6514
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: applicationmaster
> Reporter: Varun Saxena
> Assignee: Varun Saxena
> Priority: Blocker
> Attachments: MAPREDUCE-6514.01.patch, MAPREDUCE-6514.02.patch
>
>
> In RMContainerAllocator#preemptReducesIfNeeded, we simply clear the scheduled
> reduces map and put these reducers to pending. This is not updated in ask. So
> RM keeps on assigning and AM is not able to assign as no reducer is
> scheduled(check logs below the code).
> If this is updated immediately, RM will be able to schedule mappers
> immediately which anyways is the intention when we ramp down reducers.
> Scheduler need not allocate for ramped down reducers
> This if not handled can lead to map starvation as pointed out in
> MAPREDUCE-6513
> {code}
> LOG.info("Ramping down all scheduled reduces:"
> + scheduledRequests.reduces.size());
> for (ContainerRequest req : scheduledRequests.reduces.values()) {
> pendingReduces.add(req);
> }
> scheduledRequests.reduces.clear();
> {code}
> {noformat}
> 2015-10-13 04:55:04,912 INFO [RMCommunicator Allocator]
> org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: Container not
> assigned : container_1437451211867_1485_01_000215
> 2015-10-13 04:55:04,912 INFO [RMCommunicator Allocator]
> org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: Cannot assign
> container Container: [ContainerId: container_1437451211867_1485_01_000216,
> NodeId: hdszzdcxdat6g06u04p:26009, NodeHttpAddress:
> hdszzdcxdat6g06u04p:26010, Resource: <memory:4096, vCores:1>, Priority: 10,
> Token: Token { kind: ContainerToken, service: 10.2.33.236:26009 }, ] for a
> reduce as either container memory less than required 4096 or no pending
> reduce tasks - reduces.isEmpty=true
> 2015-10-13 04:55:04,912 INFO [RMCommunicator Allocator]
> org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: Container not
> assigned : container_1437451211867_1485_01_000216
> 2015-10-13 04:55:04,912 INFO [RMCommunicator Allocator]
> org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: Cannot assign
> container Container: [ContainerId: container_1437451211867_1485_01_000217,
> NodeId: hdszzdcxdat6g06u06p:26009, NodeHttpAddress:
> hdszzdcxdat6g06u06p:26010, Resource: <memory:4096, vCores:1>, Priority: 10,
> Token: Token { kind: ContainerToken, service: 10.2.33.239:26009 }, ] for a
> reduce as either container memory less than required 4096 or no pending
> reduce tasks - reduces.isEmpty=true
> {noformat}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: mapreduce-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: mapreduce-issues-h...@hadoop.apache.org
