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https://issues.apache.org/jira/browse/ARTEMIS-2782?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17117895#comment-17117895
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Justin Bertram commented on ARTEMIS-2782:
-----------------------------------------
Looking at the code I don't yet see how it's possible for
{{org.apache.activemq.artemis.core.protocol.mqtt.MQTTSession#getSessionState}}
to return {{null}} because the {{state}} is initialized when the
{{MQTTSession}} is instantiated and it never set to {{null}} after that.
Is this something you're able to reproduce? If so, can you provide me with a
reproducer?
> MQTT connection failure handling may lead to NPE
> ------------------------------------------------
>
> Key: ARTEMIS-2782
> URL: https://issues.apache.org/jira/browse/ARTEMIS-2782
> Project: ActiveMQ Artemis
> Issue Type: Bug
> Affects Versions: 2.11.0
> Reporter: Keith Wall
> Priority: Major
>
> Our (EnMasse) automated test suite includes some MQTT use-cases that rely on
> Artemis's native MQTT support. A recent test run failed as follows:
> {noformat}
> 2020-05-26T05:04:21.293Z INFO [message] AMQ601500: User test is sending a
> core message on target resource: ServerSessionImpl() [with parameters: [null,
> org.apache.activemq.artemis.protocol.amqp.broker.AMQPMessage@50b01c3e, true,
> false, RoutingContextImpl(Address=jmsTopicDurSubs, routingType=MULTICAST,
> PreviousAddress=jmsTopicDurSubs previousRoute:MULTICAST, reusable=true,
> version=-2147470526)
> 2020-05-26T05:04:21.293Z INFO [message] AMQ601500: User test is sending a
> core message on target resource: ServerSessionImpl() [with parameters: [null,
> org.apache.activemq.artemis.protocol.amqp.broker.AMQPMessage@50b01c3e, true,
> false, RoutingContextImpl(Address=jmsTopicDurSubs, routingType=MULTICAST,
> PreviousAddress=jmsTopicDurSubs previousRoute:MULTICAST, reusable=true,
> version=-2147470526)..................................................*****
> durable queues jmsTopicDurSubs:- queueID=279451 address:jmsTopicDurSubs
> name:jmsCliId.sub1DurSub filter:null- queueID=279456 address:jmsTopicDurSubs
> name:jmsCliId.sub2DurSub filter:null***** non durable for
> jmsTopicDurSubs:Exception in thread "Thread-10" java.lang.NullPointerException
> at
> org.apache.activemq.artemis.core.protocol.mqtt.MQTTConnectionManager.disconnect(MQTTConnectionManager.java:146)
> at
> org.apache.activemq.artemis.core.protocol.mqtt.MQTTFailureListener.connectionFailed(MQTTFailureListener.java:37)
> at
> org.apache.activemq.artemis.core.protocol.mqtt.MQTTConnection.fail(MQTTConnection.java:149)
> at
> org.apache.activemq.artemis.core.remoting.server.impl.RemotingServiceImpl.issueFailure(RemotingServiceImpl.java:572)
> at
> org.apache.activemq.artemis.core.remoting.server.impl.RemotingServiceImpl.connectionException(RemotingServiceImpl.java:578)
> at
> org.apache.activemq.artemis.core.remoting.impl.netty.NettyAcceptor$Listener$1.run(NettyAcceptor.java:920)
> {noformat}
>
> I don't understand the root cause that caused the MQTT connection to be
> closed, but the stack trace highlights a problem in the error handlng in
> MQTTConnectionManager.disconnect. If the session.getSessionState() returns
> null, as synchronising on a null is disallowed, the method will end with a
> NPE exception.
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