Re: [jetty-users] Bad __context set in WebAppContext.start sequence with

[Jan Bartel <janb@xxxxxxxxxxx>]

Hi Henning,

That looks like a genuine bug to me!

I opened https://bugs.eclipse.org/bugs/show_bug.cgi?id=389956

I'll take a look at this today.

Jan

On 19 September 2012 00:21, Henning Blohm <henning.blohm@xxxxxxxxxx> wrote:
> We are embedding Jetty and today we noticed the following not quite trivial
> bug in Jetty's start handling for Web apps.
>
> This bug was observed on Jetty 8.1.4 and as far as I can tell the relevant
> code has not changed since then. It happens when you start a WebAppContext
> from within a running Web app, i.e. while processing a request. In our
> scenario, a Web app may be started on-demand and the trigger to do so may
> occur while in a Web app.
>
> I checked with Jetty 6.1.22 (old integration) and it works ok there - I did
> not debug it all the way through to see why it works there and not in 8.1.4.
>
> Here is what happens:
>
> When calling WebAppContext.start() you end up in WebAppContext.doStart()
> which has this control flow:
>
> preConfigure();
> super.doStart();
> postConfigure();
>
> In preConfigure, eventually EnvConfiguration.preConfigure(<context>) is
> called and that is setting up the JNDI ENC.
>
> And here is where ContextFactory comes into the game:
>
> When looking for the class loader to identify a "java:comp" ENC from,
> ContextFactory.getObjectInstance first consults
> ContextHandler.getCurrentContext(). Only if that returns null, the current
> thread's context class loader is considered.
>
> However, the switch of Jetty Contexts in ContextHandler is done in
> ContextHandler.doStart(), i.e. only after the call to preConfigure() in
> WebAppContext.doStart().
>
> Now, if you are not in a Web App and you want to start a WebAppContext and
> the current thread's context classloader is set, then
> ContextHandler.getCurrentContext()==null and you get an ENC for the new Web
> App as expected.
>
> But if you are currently processing a Web app request, then
> ContextHandler.doScope will have set that Web app's context and
> ContextHandler.getCurrentContext()!=null and ContextFactory will try to
> create an ENC for a loader that already has one and you get:
>
> Caused by: javax.naming.NamingException: This context is immutable;
> remaining name 'env'
>    at
> org.eclipse.jetty.jndi.NamingContext.createSubcontext(NamingContext.java:302)
>    at
> org.eclipse.jetty.jndi.NamingContext.createSubcontext(NamingContext.java:383)
>    at
> org.eclipse.jetty.plus.webapp.EnvConfiguration.createEnvContext(EnvConfiguration.java:253)
>    at
> org.eclipse.jetty.plus.webapp.EnvConfiguration.preConfigure(EnvConfiguration.java:67)
>    at
> org.eclipse.jetty.webapp.WebAppContext.preConfigure(WebAppContext.java:430)
>    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:466)
>    at
> org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
>
> Please let me know, if there is some way of getting around this. Hope there
> was sufficient details and sorry for the complex case.
>
> Thanks,
>   Henning
> _______________________________________________
> jetty-users mailing list
> jetty-users@xxxxxxxxxxx
> https://dev.eclipse.org/mailman/listinfo/jetty-users



-- 
Jan Bartel <janb@xxxxxxxxxxx>
www.webtide.com – Developer advice, services and support
from the Jetty & CometD experts.