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NullPointerException on connection disposal

See original GitHub issue

Hey, folks!

We’ve noticed the following error periodically when the connections are being disposed. If I’m reading the exception correctly, it seems like the collection stores null at some point.

java.lang.NullPointerException: null
    at java.lang.Iterable.forEach(Iterable.java:75)
    at io.rsocket.core.RSocketResponder.cleanUpSendingSubscriptions(RSocketResponder.java:274)
    at io.rsocket.core.RSocketResponder.cleanup(RSocketResponder.java:264)
    at io.rsocket.core.RSocketResponder.tryTerminate(RSocketResponder.java:166)
    at io.rsocket.core.RSocketResponder.tryTerminateOnConnectionClose(RSocketResponder.java:159)
    at reactor.core.publisher.LambdaMonoSubscriber.onComplete(LambdaMonoSubscriber.java:132)
    at reactor.core.publisher.MonoProcessor$NextInner.onComplete(MonoProcessor.java:518)
    at reactor.core.publisher.MonoProcessor.onNext(MonoProcessor.java:308)
    at reactor.core.publisher.MonoProcessor.onComplete(MonoProcessor.java:265)
    at io.rsocket.internal.BaseDuplexConnection.dispose(BaseDuplexConnection.java:23)
    at ...

Steps to Reproduce

It seems that the error isn’t easily reproducible. We’re only seeing very rarely, once or twice a day.

Your Environment

RSocket version(s) used: 1.0.1
Other relevant libraries versions (eg. netty, …): none
Platform (eg. JVM version (javar -version) or Node version (node --version)): 13
OS and version (eg uname -a): ubuntu 20.04

Issue Analytics

State:
Created 3 years ago
Comments:8 (6 by maintainers)

Top GitHub Comments

1reaction

rstoyanchevcommented, Oct 6, 2020

This should be resolved now.

1reaction

OlegDokukacommented, Oct 1, 2020

Hey @SerCeMan!

Thank you for reporting that! I will have a look.

On the root-cause… Not sure we put null somewhere, it is more likely a racing between cleanup during disposal and a stream that does self-removal from the same collection when it is terminated.

So it may be that the iterator has seen an element but a collection has already been shrunken so once a next is called, the element being observed is null, hence we see NPE.

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