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https://issues.apache.org/jira/browse/AMQ-5426?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15363201#comment-15363201
]
Christopher L. Shannon commented on AMQ-5426:
---------------------------------------------
I reverted the original fix as there was still a bit of a race condition in
that it was possible an ack could be blown away or missed if the timer task for
batch ack dispatch executed while a message was received.
The new fix is a lot simpler because it leverages the already existing
deliveredMessages lock to protect the pendingAck variable and will make sure
that everything is consistent.
> ActiveMQMessageConsumer could run into NPE due to concurrent access to
> internal state
> -------------------------------------------------------------------------------------
>
> Key: AMQ-5426
> URL: https://issues.apache.org/jira/browse/AMQ-5426
> Project: ActiveMQ
> Issue Type: Bug
> Components: JMS client
> Affects Versions: 5.8.0, 5.9.1, 5.10.0
> Reporter: Michael Wong
> Assignee: Christopher L. Shannon
> Priority: Minor
> Fix For: 5.14.0, 5.13.4
>
> Attachments: AMQ5426Test.java
>
>
> ActiveMQMessageConsumer could run into NPE when the consumer is closing and a
> message arrived at the same time.
> Here is the stacktrace:
> java.lang.NullPointerException
> at
> org.apache.activemq.ActiveMQMessageConsumer.ackLater(ActiveMQMessageConsumer.java:979)
> at
> org.apache.activemq.ActiveMQMessageConsumer.afterMessageIsConsumed(ActiveMQMessageConsumer.java:929)
> at
> org.apache.activemq.ActiveMQMessageConsumer.dispatch(ActiveMQMessageConsumer.java:1323)
> at
> org.apache.activemq.ActiveMQSessionExecutor.dispatch(ActiveMQSessionExecutor.java:131)
> at
> org.apache.activemq.ActiveMQSessionExecutor.iterate(ActiveMQSessionExecutor.java:202)
> at
> org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129)
> at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
> at java.lang.Thread.run(Thread.java:745)
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