[YARN-3919] NPEs' while stopping service after exception during CommonNodeLabelsManager#start

• Type: Bug
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 2.7.0
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Component/s: resourcemanager
• Target Version/s: 2.7.2
• Hadoop Flags: Reviewed
• Assignee: Varun Saxena
• Reporter: Varun Saxena
• Created: 12/Jul/15 18:58
• Updated: 30/Aug/16 01:19
• Resolved: 29/Jul/15 18:16

Description

We get NPE during CommonNodeLabelsManager#serviceStop and AsyncDispatcher#serviceStop if ConnectException on call to CommonNodeLabelsManager#serviceStart occurs.

2015-07-10 19:39:37,825 WARN main-EventThread org.apache.hadoop.service.AbstractService: When stopping the service org.apache.hadoop.yarn.nodelabels.CommonNodeLabelsManager : java.lang.NullPointerException
java.lang.NullPointerException
        at org.apache.hadoop.yarn.nodelabels.FileSystemNodeLabelsStore.close(FileSystemNodeLabelsStore.java:99)
        at org.apache.hadoop.yarn.nodelabels.CommonNodeLabelsManager.serviceStop(CommonNodeLabelsManager.java:278)
        at org.apache.hadoop.service.AbstractService.stop(AbstractService.java:221)
        at org.apache.hadoop.service.ServiceOperations.stop(ServiceOperations.java:52)
        at org.apache.hadoop.service.ServiceOperations.stopQuietly(ServiceOperations.java:80)
        at org.apache.hadoop.service.AbstractService.start(AbstractService.java:203)
        at org.apache.hadoop.service.CompositeService.serviceStart(CompositeService.java:120)
        at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager$RMActiveServices.serviceStart(ResourceManager.java:588)
        at org.apache.hadoop.service.AbstractService.start(AbstractService.java:193)
        at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager.startActiveServices(ResourceManager.java:998)
        at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager$1.run(ResourceManager.java:1039)
        at org.apache.hadoop.yarn.server.resourcemanager.ResourceManager$1.run(ResourceManager.java:1035)

java.lang.NullPointerException
        at org.apache.hadoop.yarn.event.AsyncDispatcher.serviceStop(AsyncDispatcher.java:142)
        at org.apache.hadoop.service.AbstractService.stop(AbstractService.java:221)
        at org.apache.hadoop.service.ServiceOperations.stop(ServiceOperations.java:52)
        at org.apache.hadoop.service.ServiceOperations.stopQuietly(ServiceOperations.java:80)
        at org.apache.hadoop.service.CompositeService.stop(CompositeService.java:157)
        at org.apache.hadoop.service.CompositeService.serviceStop(CompositeService.java:131)
        at org.apache.hadoop.service.AbstractService.stop(AbstractService.java:221)
        at org.apache.hadoop.service.ServiceOperations.stop(ServiceOperations.java:52)
        at org.apache.hadoop.service.ServiceOperations.stopQuietly(ServiceOperations.java:80)

These NPEs' fill up the logs. Although, this doesn't cause any functional issue but its a nuisance and we ideally should have null checks in serviceStop.