codelipenghui opened a new pull request, #24476:
URL: https://github.com/apache/pulsar/pull/24476
### Issue Description (on version 3.0.10)
- Location: MultiTopicsConsumerImpl.java:581 in the
negativeAcknowledge(Message<?> message) method
- Error: java.lang.NullPointerException
- Root Cause: Race condition between closeAsync() and
negativeAcknowledge() methods
Technical Details
What was happening:
1. closeAsync() sets consumer state to Closing/Closed and calls
cleanupMultiConsumer()
2. cleanupMultiConsumer() sets unAckedMessageTracker = null (line 685)
3. Concurrently, negativeAcknowledge() methods were still being called
4. These methods accessed unAckedMessageTracker.remove(messageId) without
checking if it was null
5. This caused NullPointerException at line 581
Race condition timeline:
Thread 1: closeAsync() → setState(Closed) → cleanupMultiConsumer() →
unAckedMessageTracker = null
Thread 2: negativeAcknowledge() → unAckedMessageTracker.remove() → NPE!
The original stacktrace:
```
Stacktrace:
java.lang.NullPointerException: null
class java.lang.NullPointerException: null
at
org.apache.pulsar.client.impl.MultiTopicsConsumerImpl.negativeAcknowledge(MultiTopicsConsumerImpl.java:581)
at
com.company.pulsar.FutureAsyncHandler.negativeAcknowledgeAsync(FutureAsyncHandler.scala:98)
at
com.company.pulsar.FutureAsyncHandler.negativeAcknowledgeAsync(FutureAsyncHandler.scala:25)
at
com.company.pulsar.consumer.DefaultConsumer.negativeAcknowledgeAsync(Consumer.scala:135)
at
com.company.pulsar.consumer.PulsarCommittableSourceGraphStage$CommittableMessageImpl.nack(CommittableSour
ce.scala:134)
at
com.company.pulsar.PulsarTracer$TracedCommittableMessage.$anonfun$nack$1(PulsarTracer.scala:127)
at
com.company.pulsar.PulsarTracer$TracedCommittableMessage.$anonfun$wrapReply$1(PulsarTracer.scala:112)
at
com.company.domainapi.tracer.TraceFactory.$anonfun$decoratedOrigFn$1(TraceFactory.scala:93)
at
com.company.tracer.TraceFactoryImpl.buildSpanAroundFuture(TraceFactoryImpl.scala:197)
at
com.company.tracer.TraceFactoryImpl.$anonfun$tracedFt$1(TraceFactoryImpl.scala:123)
at
com.company.domainapi.tracer.TraceFactory.wrapChildCreation(TraceFactory.scala:161)
at
com.company.domainapi.tracer.TraceFactory.wrapChildCreation$(TraceFactory.scala:150)
at
com.company.tracer.TraceFactoryImpl.wrapChildCreation(TraceFactoryImpl.scala:29)
at
com.company.tracer.TraceFactoryImpl.tracedFt(TraceFactoryImpl.scala:123)
at com.company.tracer.SpanTrace.childFt(BaseTrace.scala:121)
at
com.company.pulsar.PulsarTracer$TracedCommittableMessage.wrapReply(PulsarTracer.scala:108)
at
com.company.pulsar.PulsarTracer$TracedCommittableMessage.nack(PulsarTracer.scala:127)
at
com.company.pulsar.PulsarConsumerService$anonfun$nestedInanonfun$enqueueAndStartTask$3$1.applyOrElse(Puls
arConsumerService.scala:749)
at
com.company.pulsar.PulsarConsumerService$anonfun$nestedInanonfun$enqueueAndStartTask$3$1.applyOrElse(Puls
arConsumerService.scala:746)
at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:490)
at
org.apache.pekko.dispatch.BatchingExecutor$AbstractBatch.processBatch(BatchingExecutor.scala:73)
at
org.apache.pekko.dispatch.BatchingExecutor$BlockableBatch.$anonfun$run$1(BatchingExecutor.scala:110)
at
scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
at
scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:94)
at
org.apache.pekko.dispatch.BatchingExecutor$BlockableBatch.run(BatchingExecutor.scala:110)
at
org.apache.pekko.dispatch.TaskInvocation.run(AbstractDispatcher.scala:59)
at
org.apache.pekko.dispatch.ForkJoinExecutorConfigurator$PekkoForkJoinTask.exec(ForkJoinExecutorConfigurato
r.scala:57)
at
java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
at
java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
at
java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
at
java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
at
java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)
```
### Does this pull request potentially affect one of the following parts:
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*If the box was checked, please highlight the changes*
- [ ] Dependencies (add or upgrade a dependency)
- [ ] The public API
- [ ] The schema
- [ ] The default values of configurations
- [ ] The threading model
- [ ] The binary protocol
- [ ] The REST endpoints
- [ ] The admin CLI options
- [ ] The metrics
- [ ] Anything that affects deployment
### Documentation
<!-- DO NOT REMOVE THIS SECTION. CHECK THE PROPER BOX ONLY. -->
- [ ] `doc` <!-- Your PR contains doc changes. -->
- [ ] `doc-required` <!-- Your PR changes impact docs and you will update
later -->
- [x] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->
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