[jira] [Updated] (AMQ-5263) Method ActiveMQSession.close() is not thread safe as declared and required

["Krzysztof Mackowiak (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/AMQ-5263?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Krzysztof Mackowiak updated AMQ-5263:
-------------------------------------
    Attachment: AMQ-5263_test_for_ActiveMQSession_close()_thread-safety.patch

> Method ActiveMQSession.close() is not thread safe as declared and required
> --------------------------------------------------------------------------
>
>                 Key: AMQ-5263
>                 URL: https://issues.apache.org/jira/browse/AMQ-5263
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: JMS client
>    Affects Versions: 5.9.1
>         Environment: any operationg system, and any platform
>            Reporter: Jiang Fuqiang
>            Priority: Major
>         Attachments: AMQ-5263_test_for_ActiveMQSession_close()_thread-safety.patch
>
>
> If ActiveMQSession.close()  and  ActiveMQSession.dispose() run concurrently,  the statements in close() method might throw NullPointerException。Just marked by the following code snippet.
> -------------------------------
>     public void ActiveMQSession.close() throws JMSException {
>         if (!closed) {
>             if (getTransactionContext().isInXATransaction()) { // it might throw NullPointerException
> 			...
> -------------------------------
> In my application, I call Session.close() when I detect JMSException, but Session.close() throws NullPointerException occasionally。I suspect that's because ActiveMQConnection called ActiveMQSession.dispose() in case of transport error, and  ActiveMQSession.dispose() nullified ActiveMQSession.transactionContext before ActiveMQSession.closed is assigned to false. Since this NullPointerException error just happened once and can not be reproduced, it's only a suspection. 
> It seems that close() and dispose() should be synchronized, and then sessions can be closed safely.
> I'm not good at English, but I hope this issue is demonstrated clearly enough.



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