[jira] [Commented] (NET-532) NPE in nntp.Threader.thread() when all messages in a derived thread are missing.

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

    [ https://issues.apache.org/jira/browse/NET-532?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13958899#comment-13958899 ] 

Sebb commented on NET-532:
--------------------------

Thanks for the patch.

Can you provide details of the news group and some threads that exhibit the problem please?

> NPE in nntp.Threader.thread() when all messages  in a derived thread are missing.
> ---------------------------------------------------------------------------------
>
>                 Key: NET-532
>                 URL: https://issues.apache.org/jira/browse/NET-532
>             Project: Commons Net
>          Issue Type: Bug
>          Components: NNTP
>    Affects Versions: 3.0, 3.3
>            Reporter: Elliot Shank
>         Attachments: threader.patch
>
>
> I'm threading emails using the References: header. When I've got an incomplete set of messages (in this specific case, it's from one of the C++ standards committee lists) such that I'm missing an entire thread, I get exceptions like this:
> {noformat}
> Exception in thread "main" java.lang.NullPointerException
>      at org.apache.commons.net.nntp.Threader.gatherSubjects(Threader.java:342)
>      at org.apache.commons.net.nntp.Threader.thread(Threader.java:81)
>      at org.apache.commons.net.nntp.Threader.thread(Threader.java:47)
> {noformat}
> What happens is that the graph returned by findRootSet() at line 71 will look something like
> {noformat}
>      ...
>      <ThreadContainer A with Threadable>
>          ...
>      <ThreadContainer B without Threadable>
>          <ThreadContainer ... without Threadable>
>              <ThreadContainer ... without Threadable>
>              <ThreadContainer ... without Threadable>
>          <ThreadContainer ... without Threadable>
>              <ThreadContainer ... without Threadable>
>                  <ThreadContainer ... without Threadable>
>      <ThreadContainer C with Threadable>
>          ...
>      ...
> {noformat}
> And, after pruneEmptyContainers() has had its way with things on line 75, the graph will be
> {noformat}
>      ...
>      <ThreadContainer A with Threadable>
>          ...
>      <ThreadContainer B without Threadable>
>      <ThreadContainer C with Threadable>
>          ...
>      ...
> {noformat}
> when it should be
> {noformat}
>      ...
>      <ThreadContainer A with Threadable>
>          ...
>      <ThreadContainer C with Threadable>
>          ...
>      ...
> {noformat}
> I.e., ThreadContainer B should be eliminated entirely.
> As it is, with ThreadContainer B present, but not containing any children or a Threadable, gatherSubjects() chokes.



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