[ https://issues.apache.org/jira/browse/MAPREDUCE-4607?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Bikas Saha updated MAPREDUCE-4607: ---------------------------------- Attachment: MAPREDUCE-4607.1.patch Attaching patch with the proposed fix. > Race condition in ReduceTask completion can result in Task being incorrectly > failed > ----------------------------------------------------------------------------------- > > Key: MAPREDUCE-4607 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-4607 > Project: Hadoop Map/Reduce > Issue Type: Bug > Affects Versions: 2.1.0-alpha > Reporter: Bikas Saha > Assignee: Bikas Saha > Attachments: MAPREDUCE-4607.1.patch > > > Problem reported by chackaravarthy in MAPREDUCE-4252 > This problem has been handled when speculative task launched for map task and > other attempt got failed (not killed) > Can the similar kind of scenario can happen in case of reduce task? > Consider the following scenario for reduce task in case of speculation (one > attempt got killed): > 1. A task attempt is started. > 2. A speculative task attempt for the same task is started. > 3. The first task attempt completes and causes the task to transition to > SUCCEEDED. > 4. Then speculative task attempt will be killed because of the completion of > first attempt. > As a result, internal error will be thrown from this attempt > (TaskImpl.MapRetroactiveKilledTransition) and hence task attempt failure > leads to job failure. > TaskImpl.MapRetroactiveKilledTransition > if (!TaskType.MAP.equals(task.getType())) { > LOG.error("Unexpected event for REDUCE task " + event.getType()); > task.internalError(event.getType()); > } > So, do we need to have following code in MapRetroactiveKilledTransition also > just like in MapRetroactiveFailureTransition. > if (event instanceof TaskTAttemptEvent) { > TaskTAttemptEvent castEvent = (TaskTAttemptEvent) event; > if (task.getState() == TaskState.SUCCEEDED && > !castEvent.getTaskAttemptID().equals(task.successfulAttempt)) { > // don't allow a different task attempt to override a previous > // succeeded state > return TaskState.SUCCEEDED; > } > } > please check whether this is a valid case and give your suggestion. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira