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From Rohith Sharma K S <rohithsharm...@huawei.com>
Subject Reducers are launched after jobClient is exited.
Date Wed, 29 Jan 2014 03:12:40 GMT
Hi All ,

             I ran job with 1 Map and 1 Reducers ( mapreduce.job.reduce.slowstart.completedmaps=1
).  Map failed ( because of error in Mapper implementation), but still Reducers are launched
by applicationMaster.  These reducers killed by applicationMaster while

stopping RMCommunicator service.


1.       Why Reducers are launching after job is finished.? ( Is this is bug in MR? )



Our use case is when job is finished(succeeded/failed),client program delete the JobOutput
directory. Here, jobclient exit immediately after jobStatus is set. ( in below log, at 2014-01-23
07:34:43,166)



But , in the below log as mentioned reducers are launched later , Reducer temporary directory
and files are created(_temporary). These files left in hdfs undeleted forever.

Kindly suggest your thoughts, how we can handle this situation?



2014-01-23 07:34:43,151 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.TaskImpl:
task_1389970937094_0047_m_000000 Task Transitioned from RUNNING to FAILED
2014-01-23 07:34:43,151 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl:
Num completed Tasks: 1
2014-01-23 07:34:43,151 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl:
Job failed as tasks failed. failedMaps:1 failedReduces:0
2014-01-23 07:34:43,153 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl:
job_1389970937094_0047Job Transitioned from RUNNING to FAIL_ABORT
2014-01-23 07:34:43,153 INFO [CommitterEvent Processor #0] org.apache.hadoop.mapreduce.v2.app.commit.CommitterEventHandler:
Processing the event EventType: JOB_ABORT
2014-01-23 07:34:43,166 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl:
job_1389970937094_0047Job Transitioned from FAIL_ABORT to FAILED
...............
...............
2014-01-23 07:34:43,707 INFO [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator:
Before Scheduling: PendingReds:1 ScheduledMaps:0 ScheduledReds:0 AssignedMaps:1 AssignedReds:0
CompletedMaps:1 CompletedReds:0 ContAlloc:4 ContRel:0 HostLocal:1 RackLocal:0
2014-01-23 07:34:43,709 INFO [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator:
Recalculating schedule, headroom=12288
2014-01-23 07:34:43,709 INFO [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator:
Reduce slow start threshold reached. Scheduling reduces.
2014-01-23 07:34:43,709 INFO [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator:
All maps assigned. Ramping up all remaining reduces:1
...............
...............
2014-01-23 07:34:45,714 INFO [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator:
Got allocated containers 1
2014-01-23 07:34:45,714 INFO [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator:
Assigned to reduce
2014-01-23 07:34:45,714 INFO [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator:
Assigned container container_1389970937094_0047_01_000006 to attempt_1389970937094_0047_r_000000_0
...............
...............
2014-01-23 07:34:45,724 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.TaskAttemptImpl:
attempt_1389970937094_0047_r_000000_0 TaskAttempt Transitioned from UNASSIGNED to ASSIGNED
2014-01-23 07:34:45,725 INFO [ContainerLauncher #8] org.apache.hadoop.mapreduce.v2.app.launcher.ContainerLauncherImpl:
Processing the event EventType: CONTAINER_REMOTE_LAUNCH for container container_1389970937094_0047_01_000006
taskAttempt attempt_1389970937094_0047_r_000000_0
2014-01-23 07:34:45,725 INFO [ContainerLauncher #8] org.apache.hadoop.mapreduce.v2.app.launcher.ContainerLauncherImpl:
Launching attempt_1389970937094_0047_r_000000_0
2014-01-23 07:34:45,727 INFO [ContainerLauncher #8] org.apache.hadoop.mapreduce.v2.app.launcher.ContainerLauncherImpl:
Shuffle port returned by ContainerManager for attempt_1389970937094_0047_r_000000_0 : 11234
2014-01-23 07:34:45,728 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.TaskAttemptImpl:
TaskAttempt: [attempt_1389970937094_0047_r_000000_0] using containerId: [container_1389970937094_0047_01_000006
on NM: [linux85:11232]
2014-01-23 07:34:45,728 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.TaskAttemptImpl:
attempt_1389970937094_0047_r_000000_0 TaskAttempt Transitioned from ASSIGNED to RUNNING
2014-01-23 07:34:45,728 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.TaskImpl:
task_1389970937094_0047_r_000000 Task Transitioned from SCHEDULED to RUNNING
...............
.............
2014-01-23 07:34:48,178 INFO [Thread-59] org.apache.hadoop.mapreduce.v2.app.launcher.ContainerLauncherImpl:
KILLING attempt_1389970937094_0047_r_000000_0
2014-01-23 07:34:48,180 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.TaskAttemptImpl:
attempt_1389970937094_0047_r_000000_0 TaskAttempt Transitioned from RUNNING to KILLED
...............
.............


Thanks & Regards
Rohith


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