[SAMZA-1346] GroupByContainerCount.balance() should guard against null LocalityManager

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.13.1
• Assignee: Jake Maes
• Reporter: Jake Maes
• Created: 26/Jun/17 16:17
• Updated: 26/Jun/17 20:44
• Resolved: 26/Jun/17 20:43

Description

While it's less likely after SAMZA-1334, we have seen cases of an NPE in embedded mode.

org.apache.samza.SamzaException: Failed to run application
	at org.apache.samza.runtime.LocalApplicationRunner.run(LocalApplicationRunner.java:136)
	at com.linkedin.beam.runners.samza.runtime.fluent.FluentRuntime$RunnerTask.run(FluentRuntime.java:114)
	... 1 more
Caused by: java.lang.NullPointerException
	at org.apache.samza.container.grouper.task.GroupByContainerCount.balance(GroupByContainerCount.java:92)
	at org.apache.samza.coordinator.JobModelManager$.readJobModel(JobModelManager.scala:257)
	at org.apache.samza.coordinator.JobModelManager.readJobModel(JobModelManager.scala)
	at org.apache.samza.standalone.StandaloneJobCoordinator.<init>(StandaloneJobCoordinator.java:108)
	at org.apache.samza.standalone.StandaloneJobCoordinatorFactory.getJobCoordinator(StandaloneJobCoordinatorFactory.java:29)
	at org.apache.samza.processor.StreamProcessor.<init>(StreamProcessor.java:111)
	at org.apache.samza.processor.StreamProcessor.<init>(StreamProcessor.java:94)
	at org.apache.samza.runtime.LocalApplicationRunner.createStreamProcessor(LocalApplicationRunner.java:231)
	at org.apache.samza.runtime.LocalApplicationRunner.lambda$run$0(LocalApplicationRunner.java:125)
	at org.apache.samza.runtime.LocalApplicationRunner$$Lambda$35/1940982718.accept(Unknown Source)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.apache.samza.runtime.LocalApplicationRunner.run(LocalApplicationRunner.java:121)
	... 2 more

It should be straight forward to defend against this case and provide better feedback in the logs. E.g. if the locality manager is null, then host affinity is not enabled and we could just defer to group().

Issue Links

• links to: GitHub Pull Request #232