MapReduce AppMaster and YARN at large use asynchronous event handling inside the JVM and so you may run into race conditions like this.
Even otherwise, doing this in a deterministic manner is better achieved by overriding your OutputCommitter. Job output commit/abort happens only once. +Vinod On Jan 28, 2014, at 7:06 PM, Rohith Sharma K S <rohithsharm...@huawei.com> wrote: > 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 -- CONFIDENTIALITY NOTICE NOTICE: This message is intended for the use of the individual or entity to which it is addressed and may contain information that is confidential, privileged and exempt from disclosure under applicable law. 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