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https://issues.apache.org/jira/browse/DERBY-4304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12735102#action_12735102
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Mamta A. Satoor commented on DERBY-4304:
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Tiago noticed (
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https://issues.apache.org/jira/browse/DERBY-4306?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12731644#action_12731644
]) following NPE with my checkin 796316 (which has been rolled back)
at
org.apache.derby.impl.drda.NetworkServerControlImpl.isMsgProperty(NetworkServerControlImpl.java:3460)
at
org.apache.derby.impl.drda.NetworkServerControlImpl.localizeMessage(NetworkServerControlImpl.java:3397)
at
org.apache.derby.impl.drda.NetworkServerControlImpl.consolePropertyMessageWork(NetworkServerControlImpl.java:3195)
at
org.apache.derby.impl.drda.NetworkServerControlImpl.consolePropertyMessage(NetworkServerControlImpl.java:1888)
at
org.apache.derby.impl.drda.NetworkServerControlImpl.blockingStart(NetworkServerControlImpl.java:895)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at
org.apache.derby.iapi.jdbc.DRDAServerStarter.run(DRDAServerStarter.java:236)
at java.lang.Thread.run(Thread.java:619)
I debugged the NPE and found that my try catch block below was getting NPE from
mgmtService.unregisterMBean(versionMBean);
try {
mgmtService.unregisterMBean(versionMBean);
mgmtService.unregisterMBean(networkServerMBean);
} catch (Exception exception) {
consolePropertyMessage("DRDA_UnexpectedException.S",
exception.getMessage());
consoleExceptionPrintTrace(exception);
}
This NPE from mgmtService.unregisterMBean(versionMBean); is caught by the catch
clause above. The problem though is that exception.getMessage() for this NPE
returns null and our existing code for consolePropertyMessage is not written to
handle a null 2nd parameter. But the work that is being done by
consolePropertyMessage on exception.getMessage() is also done by the next line
of code in try catch block which is consoleExceptionPrintTrace(exception); In
fact, consoleExceptionPrintTrace handles the null exception.getMessage() fine.
Because of that I am suggesting that I replace the call
consolePropertyMessage("DRDA_UnexpectedException.S", exception.getMessage());
with consolePropertyMessage("DRDA_UnexpectedException.S", true);
So, the new try catch will look as follows
try {
mgmtService.unregisterMBean(versionMBean);
mgmtService.unregisterMBean(networkServerMBean);
} catch (Exception exception) {
consolePropertyMessage("DRDA_UnexpectedException.S",
true);
consoleExceptionPrintTrace(exception);
}
In fact, I am changing all the try catches introduced for different steps of
shutdown to look like above. I am running the junit tests right now. Once
derbyall and junit finish, I will go ahead and commit these changes. Any
feedback greatly appreciated.
> Network Server shutdown should handle exceptions and finish the server
> shutdown completely
> ------------------------------------------------------------------------------------------
>
> Key: DERBY-4304
> URL: https://issues.apache.org/jira/browse/DERBY-4304
> Project: Derby
> Issue Type: Improvement
> Components: Network Server
> Affects Versions: 10.6.0.0
> Reporter: Mamta A. Satoor
> Assignee: Mamta A. Satoor
> Attachments: DERBY4304_handleExceptions_patch1_diff.txt
>
>
> While working on DERBY-4053, found that an exception from Connection.close
> was not handled properly by the server shutdown code which caused a new
> instance server startup to hang. Resolved the problem with Connection close
> but in general, we should
> 1) Make sure an exception during shutdown processing does not prevent the
> remaining shutdown tasks, like closing the server socket from occurring.
> 2) Make sure any exceptions that occur in shutdown processing are reported to
> the console.
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