[jboss-jira] [JBoss JIRA] (WFCORE-1016) NPE or AssertionError if op is cancelled on slave between sending prepare and receiving commit/rollback

[Brian Stansberry (JIRA)]

    [ https://issues.jboss.org/browse/WFCORE-1016?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13113048#comment-13113048 ] 

Brian Stansberry commented on WFCORE-1016:
------------------------------------------

Turns out the responseChannel needs to be nulled for each request/response pair, as the client will only expect one response per request. Nulling the responseChannel is meant to ensure the server doesn't try to send > 1 response per request.

So the fix is deal with this situation where the responseChannel is null because the prepare response has been set, but then a final response is ready before the client has send the commit/rollback message.

> NPE or AssertionError if op is cancelled on slave between sending prepare and receiving commit/rollback
> -------------------------------------------------------------------------------------------------------
>
>                 Key: WFCORE-1016
>                 URL: https://issues.jboss.org/browse/WFCORE-1016
>             Project: WildFly Core
>          Issue Type: Bug
>          Components: Domain Management
>    Affects Versions: 2.0.0.CR5
>            Reporter: Brian Stansberry
>            Assignee: Brian Stansberry
>             Fix For: 2.0.0.CR6
>
>
> OperationCancellationTestCase showed this failure:
> {code}
> 2015-09-23 06:43:40,147 INFO  [org.jboss.as.test.integration.management.extension.blocker.BlockerExtension] (Host Controller Service Threads - 82) block requested by testSlaveBlockCompletionCancelSlave for slave/undefined(COMMIT)
> 2015-09-23 06:43:40,147 INFO  [org.jboss.as.test.integration.management.extension.blocker.BlockerExtension] (Host Controller Service Threads - 82) will block at COMMIT for 20000
> 2015-09-23 06:43:40,164 INFO  [org.jboss.as.controller.management-operation] (Host Controller Service Threads - 71) WFLYCTL0352: Cancelling operation 'block' with id '1900489784' running on thread 'Host Controller Service Threads - 82'
> 2015-09-23 06:43:40,185 ERROR [stderr] (Host Controller Service Threads - 82) Exception in thread "Host Controller Service Threads - 82" java.lang.AssertionError
> 2015-09-23 06:43:40,185 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.remote.TransactionalProtocolOperationHandler$ExecuteRequestContext.completed(TransactionalProtocolOperationHandler.java:475)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.remote.TransactionalProtocolOperationHandler$ExecuteRequestHandler.doExecute(TransactionalProtocolOperationHandler.java:190)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.remote.TransactionalProtocolOperationHandler$ExecuteRequestHandler$1.run(TransactionalProtocolOperationHandler.java:136)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.remote.TransactionalProtocolOperationHandler$ExecuteRequestHandler$1.run(TransactionalProtocolOperationHandler.java:132)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at java.security.AccessController.doPrivileged(Native Method)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at javax.security.auth.Subject.doAs(Subject.java:360)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.AccessAuditContext.doAs(AccessAuditContext.java:81)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.remote.TransactionalProtocolOperationHandler$ExecuteRequestHandler$2$1.run(TransactionalProtocolOperationHandler.java:152)
> 2015-09-23 06:43:40,186 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.remote.TransactionalProtocolOperationHandler$ExecuteRequestHandler$2$1.run(TransactionalProtocolOperationHandler.java:148)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at java.security.AccessController.doPrivileged(Native Method)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.controller.remote.TransactionalProtocolOperationHandler$ExecuteRequestHandler$2.execute(TransactionalProtocolOperationHandler.java:148)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.protocol.mgmt.AbstractMessageHandler$2$1.doExecute(AbstractMessageHandler.java:299)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.as.protocol.mgmt.AbstractMessageHandler$AsyncTaskRunner.run(AbstractMessageHandler.java:519)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at java.lang.Thread.run(Thread.java:745)
> 2015-09-23 06:43:40,187 ERROR [stderr] (Host Controller Service Threads - 82) 	at org.jboss.threads.JBossThread.run(JBossThread.java:320)
> {code}
> What happens here is the slave HC executing the 'block' op has sent a prepare message to the master, and then when the commit has not come back yet the test driver triggers a cancel on the slave. At this point the thread running the 'block' op returns and tries to send the final result to the master. But it fails because the prepare logic has nulled out the responseChannel field, and the commit message has not arrived yet to restore a new one.
> If assertions weren't enabled, the result would be an NPE when the null responseChannel is used.
> I don't see any reason for null out the responseChannel.



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