java.lang.NullPointerException at com.amazonaws.services.kinesis.clientlibrary.lib.worker.Worker.requestShutdown(Worker.java:558)

[slam]

I upgraded KCL to 1.7.2 and modified my code to use Worker.requestShutdown() to try to do a clean shutdown.

With the change my integration test now crashes with:

java.lang.NullPointerException
	at com.amazonaws.services.kinesis.clientlibrary.lib.worker.Worker.requestShutdown(Worker.java:558)
	at com.zynga.analytics.KinesisExecutor.shutdown(KinesisExecutor.java:50)
	at com.zynga.analytics.kinesis.s3.S3ConsumerApplicationIntegrationTest.tearDown(S3ConsumerApplicationIntegrationTest.java:132)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:33)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
	at org.junit.rules.ExternalResource$1.evaluate(ExternalResource.java:48)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:237)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

A breakpoint right before the crash shows that there were 3 leases but only 1 item in the shardInfoShardConsumerMap:

leases = {HashMap$Values@6053}  size = 3
 0 = {KinesisClientLease@6056} "{\n  "leaseKey" : "shardId-000000000012",\n  "leaseOwner" : "20958db3cafdc283:c9f780a:159af1ab926:-8000",\n  "leaseCounter" : 25,\n  "concurrencyToken" : "ba712794-ab53-4f63-92af-7ab40c3c15af",\n  "lastCounterIncrementNanos" : 383997591929910,\n  "checkpoint" : {\n    "sequenceNumber" : "TRIM_HORIZON",\n    "subSequenceNumber" : 0\n  },\n  "ownerSwitchesSinceCheckpoint" : 0,\n  "parentShardIds" : [ "shardId-000000000011", "shardId-000000000010" ]\n}"
 1 = {KinesisClientLease@6076} "{\n  "leaseKey" : "shardId-000000000011",\n  "leaseOwner" : "20958db3cafdc283:c9f780a:159af1ab926:-8000",\n  "leaseCounter" : 38,\n  "concurrencyToken" : "dbb51590-f3f7-4dd8-a7a9-ce3f9b1a3192",\n  "lastCounterIncrementNanos" : 383997588740565,\n  "checkpoint" : {\n    "sequenceNumber" : "SHARD_END",\n    "subSequenceNumber" : 0\n  },\n  "ownerSwitchesSinceCheckpoint" : 0,\n  "parentShardIds" : [ "shardId-000000000009", "shardId-000000000007" ]\n}"
 2 = {KinesisClientLease@6077} "{\n  "leaseKey" : "shardId-000000000010",\n  "leaseOwner" : "20958db3cafdc283:c9f780a:159af1ab926:-8000",\n  "leaseCounter" : 39,\n  "concurrencyToken" : "551edf69-75c9-4487-aa41-787d66ff9793",\n  "lastCounterIncrementNanos" : 383997592292027,\n  "checkpoint" : {\n    "sequenceNumber" : "SHARD_END",\n    "subSequenceNumber" : 0\n  },\n  "ownerSwitchesSinceCheckpoint" : 0,\n  "parentShardIds" : [ "shardId-000000000008" ]\n}"

shardInfoShardConsumerMap = {ConcurrentHashMap@6059}  size = 1
 0 = {ConcurrentHashMap$MapEntry@6088} "ShardInfo [shardId=shardId-000000000012, concurrencyToken=ba712794-ab53-4f63-92af-7ab40c3c15af, parentShardIds=[shardId-000000000010, shardId-000000000011], checkpoint={SequenceNumber: TRIM_HORIZON,SubsequenceNumber: 0}]" -> 
  key = {ShardInfo@6089} "ShardInfo [shardId=shardId-000000000012, concurrencyToken=ba712794-ab53-4f63-92af-7ab40c3c15af, parentShardIds=[shardId-000000000010, shardId-000000000011], checkpoint={SequenceNumber: TRIM_HORIZON,SubsequenceNumber: 0}]"
  value = {ShardConsumer@6090} 

I could only reproduce this with my integration test. The test up- and down-shards the stream continuously while verifying the data going through the stream.

Interesting thing to note: The two shards that were in the leases but not in shardInfoShardConsumerMap had a sequenceNumber of SHARD_END. I suspect that the sharding activity might have something to do with the crash...

[slam]

My attempt at fixing the NPE. It is probably not tackling the root cause.

diff --git a/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java b/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java
index 2a1e548..e825d53 100644
--- a/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java
+++ b/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java
@@ -555,7 +555,10 @@ public class Worker implements Runnable {
             ShutdownNotification shutdownNotification = new ShardConsumerShutdownNotification(leaseCoordinator, lease,
                     notificationCompleteLatch, shutdownCompleteLatch);
             ShardInfo shardInfo = KinesisClientLibLeaseCoordinator.convertLeaseToAssignment(lease);
-            shardInfoShardConsumerMap.get(shardInfo).notifyShutdownRequested(shutdownNotification);
+            ShardConsumer consumer = shardInfoShardConsumerMap.get(shardInfo);
+            if (consumer != null) {
+                consumer.notifyShutdownRequested(shutdownNotification);
+            }
         }
 
         return new ShutdownFuture(shutdownCompleteLatch, notificationCompleteLatch, this);

[pfifer]

Thanks for reporting this. I'll look into getting a fix out in the ear future.

[pfifer]

This is fixed in release 1.7.4. Please reopen if you're still seeing this issue.