Keith Wall created ARTEMIS-1952:
-----------------------------------
Summary: NPE logged at warn if MQTT subscriber disconnects abruptly
Key: ARTEMIS-1952
URL: https://issues.apache.org/jira/browse/ARTEMIS-1952
Project: ActiveMQ Artemis
Issue Type: Bug
Components: MQTT
Affects Versions: 2.6.1, 2.6.0
Reporter: Keith Wall
If I connect a python paso MQTT client, create a subscriber, then disconnect
abruptly, the following stacktace appears in the Artemis log. I see the same
defect on 2.6.0 and 2.6.1 (and master). 2.5.0 didn't exhibit the issue.
If the client disconnects gracefully, or the client does not subscribe, the
issue does not appear.
Outwardly, it appears the broker is unaffected.
{noformat}
2018-06-22 11:37:07,383 WARN
[org.apache.activemq.artemis.utils.actors.OrderedExecutor] null:
java.lang.NullPointerException
at
org.apache.activemq.artemis.core.protocol.mqtt.MQTTProtocolManager.isClientConnected(MQTTProtocolManager.java:182)
[artemis-mqtt-protocol-2.7.0-SNAPSHOT.jar:]
at
org.apache.activemq.artemis.core.protocol.mqtt.MQTTConnectionManager.disconnect(MQTTConnectionManager.java:150)
[artemis-mqtt-protocol-2.7.0-SNAPSHOT.jar:]
at
org.apache.activemq.artemis.core.protocol.mqtt.MQTTFailureListener.connectionFailed(MQTTFailureListener.java:37)
[artemis-mqtt-protocol-2.7.0-SNAPSHOT.jar:]
at
org.apache.activemq.artemis.core.protocol.mqtt.MQTTConnection.fail(MQTTConnection.java:147)
[artemis-mqtt-protocol-2.7.0-SNAPSHOT.jar:]
at
org.apache.activemq.artemis.core.remoting.server.impl.RemotingServiceImpl.issueFailure(RemotingServiceImpl.java:561)
[artemis-server-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]
at
org.apache.activemq.artemis.core.remoting.server.impl.RemotingServiceImpl.connectionDestroyed(RemotingServiceImpl.java:542)
[artemis-server-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]
at
org.apache.activemq.artemis.core.remoting.impl.netty.NettyAcceptor$Listener.connectionDestroyed(NettyAcceptor.java:845)
[artemis-server-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]
at
org.apache.activemq.artemis.core.remoting.impl.netty.ActiveMQChannelHandler.lambda$channelInactive$0(ActiveMQChannelHandler.java:83)
[artemis-core-client-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]
at
org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:42)
[artemis-commons-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]
at
org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:31)
[artemis-commons-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]
at
org.apache.activemq.artemis.utils.actors.ProcessorBase.executePendingTasks(ProcessorBase.java:66)
[artemis-commons-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[rt.jar:1.8.0_171]
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[rt.jar:1.8.0_171]
at
org.apache.activemq.artemis.utils.ActiveMQThreadFactory$1.run(ActiveMQThreadFactory.java:118)
[artemis-commons-2.7.0-SNAPSHOT.jar:2.7.0-SNAPSHOT]{noformat}
The program to reproduce the issue is simply:
{code:java}
import paho.mqtt.client as mqtt
client = mqtt.Client()
client.connect("localhost", 1883, 60)
client.subscribe("any/old/thing")
# if the following line is commented, the NPE is reported to the logs of the
broker
# client.disconnect(){code}
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