NM can hang during shutdown if AppLogAggregatorImpl thread dies unexpectedly ----------------------------------------------------------------------------
Key: MAPREDUCE-3738 URL: https://issues.apache.org/jira/browse/MAPREDUCE-3738 Project: Hadoop Map/Reduce Issue Type: Bug Components: mrv2, nodemanager Affects Versions: 0.23.1, 0.24.0 Reporter: Jason Lowe If an AppLogAggregator thread dies unexpectedly (e.g.: uncaught exception like OutOfMemoryError in the case I saw) then this will lead to a hang during nodemanager shutdown. The NM calls AppLogAggregatorImpl.join() during shutdown to make sure log aggregation has completed, and that method internally waits for an atomic boolean to be set by the log aggregation thread to indicate it has finished. Since the thread was killed off earlier due to an uncaught exception, the boolean will never be set and the NM hangs during shutdown repeating something like this every second in the log file: 2012-01-25 22:20:56,366 INFO org.apache.hadoop.yarn.server.nodemanager.containermanager.logaggregation.AppLogAggregatorImpl: Waiting for aggregation to complete for application_1326848182580_2806 -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira