[jira] [Created] (SAMZA-1647) Fix NPE in JobModelExpired event handler.

["Shanthoosh Venkataraman (JIRA)" <ji...@apache.org>]

Shanthoosh Venkataraman created SAMZA-1647:
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             Summary: Fix NPE in JobModelExpired event handler.
                 Key: SAMZA-1647
                 URL: https://issues.apache.org/jira/browse/SAMZA-1647
             Project: Samza
          Issue Type: Bug
            Reporter: Shanthoosh Venkataraman
            Assignee: Shanthoosh Venkataraman


*Problem:*

There's a minor race condition in container shutdown triggered from the onJobModelExpired event handler. This race condition leads to an NPE and eventually kills the StreamProcessor.

*Reason:*

Following is the JobModelExpired event handler logic executed from the DebounceThread:
1. Invoke container shutdown. 
2. Wait for configured task.shutdown.ms through countDownLatch.
3. Log the containerId after the configured wait time.

Following is the onContainerFailed event handler logic executed from the ContainerThread:
1. pull down the countdownLatch.
2. Set the container field to null.

If the Step 2. of containerFailed handler is executed before the step 3 of JobModelExpired handler, container value will be set null before we log it in JobModelExpired handler. This results in an NPE.

Relevant stacktrace:

 
{code:java}
[p-0000000000-container-thread-0] ERROR org.apache.samza.processor.StreamProcessor - Container failed. Stopping the processor.
org.apache.samza.system.SystemProducerException: Flush failed. One or more batches of messages were not sent!
at org.apache.samza.system.kafka.KafkaSystemProducer$$anonfun$flush$1.apply$mcV$sp(KafkaSystemProducer.scala:159)
at org.apache.samza.system.kafka.KafkaSystemProducer$$anonfun$flush$1.apply(KafkaSystemProducer.scala:130)
at org.apache.samza.system.kafka.KafkaSystemProducer$$anonfun$flush$1.apply(KafkaSystemProducer.scala:130)
at org.apache.samza.util.TimerUtils$class.updateTimer(TimerUtils.scala:37)
at org.apache.samza.system.kafka.KafkaSystemProducer.updateTimer(KafkaSystemProducer.scala:39)
at org.apache.samza.system.kafka.KafkaSystemProducer.flush(KafkaSystemProducer.scala:130)
at org.apache.samza.system.SystemProducers$$anonfun$flush$2.apply(SystemProducers.scala:64)
at org.apache.samza.system.SystemProducers$$anonfun$flush$2.apply(SystemProducers.scala:64)
at scala.collection.Iterator$class.foreach(Iterator.scala:891)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
at scala.collection.MapLike$DefaultValuesIterable.foreach(MapLike.scala:206)
at org.apache.samza.system.SystemProducers.flush(SystemProducers.scala:64)
at org.apache.samza.task.TaskInstanceCollector.flush(TaskInstanceCollector.scala:69)
at org.apache.samza.container.TaskInstance.commit(TaskInstance.scala:210)
at org.apache.samza.container.SamzaContainer$$anonfun$shutdownTask$9.apply(SamzaContainer.scala:1024)
at org.apache.samza.container.SamzaContainer$$anonfun$shutdownTask$9.apply(SamzaContainer.scala:1024)
at scala.collection.Iterator$class.foreach(Iterator.scala:891)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
at scala.collection.MapLike$DefaultValuesIterable.foreach(MapLike.scala:206)
at org.apache.samza.container.SamzaContainer.shutdownTask(SamzaContainer.scala:1024)
at org.apache.samza.container.SamzaContainer.run(SamzaContainer.scala:731)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.samza.system.SystemProducerException: Failed to send message for Source: TaskName-SystemStreamPartition [TestSystemName, test-input-single-partition-topic-21194330-d462-4d98-8915-fbbac765d895, 0] on Syste m:TestSystemName Topic:test-output-single-partition-topic-21194330-d462-4d98-8915-fbbac765d895 Partition:null
at org.apache.samza.system.kafka.KafkaSystemProducer$$anon$1.onCompletion(KafkaSystemProducer.scala:109)
at org.apache.kafka.clients.producer.internals.ProducerBatch.completeFutureAndFireCallbacks(ProducerBatch.java:201)
at org.apache.kafka.clients.producer.internals.ProducerBatch.done(ProducerBatch.java:185)
at org.apache.kafka.clients.producer.internals.Sender.failBatch(Sender.java:600)
at org.apache.kafka.clients.producer.internals.Sender.sendProducerData(Sender.java:272)
at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:223)
at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:162)
... 1 more
Caused by: org.apache.kafka.common.errors.TimeoutException: Expiring 1 record(s) for test-output-single-partition-topic-21194330-d462-4d98-8915-fbbac765d895-0: 30003 ms has passed since batch creation plus linger time
[p-0000000000-container-thread-0] INFO org.apache.samza.processor.StreamProcessor - Shutting down JobCoordinator from StreamProcessor
[debounce-thread-0] INFO org.apache.samza.processor.StreamProcessor - ShutdownComplete=true
[debounce-thread-0] INFO org.apache.samza.processor.StreamProcessor - Shutting down container done for pid=0000000000; complete =true
[debounce-thread-0] ERROR org.apache.samza.zk.ZkJobCoordinator - Encountered errors during job coordinator stop.
java.lang.NullPointerException
at org.apache.samza.processor.StreamProcessor$1.onJobModelExpired(StreamProcessor.java:235)
at org.apache.samza.zk.ZkJobCoordinator.stop(ZkJobCoordinator.java:163)
at org.apache.samza.zk.ZkJobCoordinator$ZkSessionStateChangedListener.lambda$handleStateChanged$0(ZkJobCoordinator.java:449)
at org.apache.samza.zk.ScheduleAfterDebounceTime.lambda$getScheduleableAction$0(ScheduleAfterDebounceTime.java:153)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
{code}



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