[weld-dev] NullPointer in WeldInitialListener

[Andy McCright]

Hi Matej,

Thanks for the quick response.  I think you make a good point, and I have
started the conversation with the Open Liberty web container developers to
see what they think - but ultimately, I agree that it doesn't make much
sense to destroy something that was never initialized.

That said, I don't think a null check would hurt anything - this would only
occur on app shutdown, so performance shouldn't be a factor.  I'll leave it
up to you.  The changes to how the startup exception is logged in Open
Liberty fixes my primary concern (determining the original startup problem).

Thanks for considering!

Andy

On Wed, Jul 22, 2020 at 9:08 AM Matej Novotny <manovotn at redhat.com> wrote:

> Hello,
>
> thanks for reporting this.
>
> I am not quite following how you manage to register a listener, *not*
> invoke contextInitialized but attempt to invoke contextDestroyed on it?
> Is the error happening during initialization of other listeners?
> To me it seems like Liberty shouldn't try to do that, e.g. only invoke
> contextDestroyed for listeners that had a chance to perform
> contextInitialized.
> I think I saw similar approach in Undertow (used in WFLY) but I am not
> sure from the top of my head.
>
> Adding null checks is also an option of course, but I kind of think this
> situation shouldn't really happen.
> I might be wrong, feel free to disagree :)
>
> Regards
> Matej
>
> ----- Original Message -----
> > From: "Andy McCright" <j.andrew.mccright at gmail.com>
> > To: weld-dev at lists.jboss.org
> > Sent: Wednesday, July 22, 2020 3:34:35 PM
> > Subject: [weld-dev] NullPointer in WeldInitialListener
> >
> > Hi All,
> >
> > I'm using Weld in Open Liberty and seeing a NullPointerException from
> > WeldInitialListener when an app fails to start. The scenario goes
> something
> > like this:
> > 1) Server and app starts to start.
> > 2) An error occurs in my app code throwing an uncaught exception.
> > 3) Liberty's web container code then attempts to stop the
> > still-not-yet-started app - this calls the WeldInitialListener's
> > contextDestroyed method without ever calling the contextCreated method.
> > 4) Because contextCreated was never called, there is a
> NullPointerException
> > thrown from contextDestroyed (the lifecycle field is null), which ends up
> > masking the root cause of the problem.
> >
> > I am in the process of fixing part of the problem (not logging the
> original
> > exception) in Open Liberty issue 13124[1], but I wonder if we should also
> > check if lifecycle is null in the contextDestroyed method[2] to avoid the
> > NPE.
> >
> > Thanks,
> >
> > Andy
> >
> > [1] https://github.com/OpenLiberty/open-liberty/issues/13124
> > [2]
> >
> https://github.com/weld/core/blob/2fe5d1f64c03b89cc562a14cda317098225590c7/modules/web/src/main/java/org/jboss/weld/module/web/servlet/WeldInitialListener.java#L113
> >
> >
> >
> > _______________________________________________
> > weld-dev mailing list
> > weld-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/weld-dev
>
>
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