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From "Karl Pauls" <karlpa...@gmail.com>
Subject Re: using pax-logger/log4j in embedded felix (class loader issue)
Date Mon, 07 Jul 2008 20:40:14 GMT
On Mon, Jul 7, 2008 at 10:27 PM, Niclas Hedhman <niclas@hedhman.org> wrote:
> On Tue, Jul 8, 2008 at 3:26 AM, Niclas Hedhman <niclas@hedhman.org> wrote:
>> On Tue, Jul 8, 2008 at 1:31 AM, Karl Pauls <karlpauls@gmail.com> wrote:
>>> Is it somehow possible that log4j is
>>> doing some classloader magic itself and maybe is using the context
>>> classloader? The context classloader would be the WebAppClassloader I
>>> think ...
>>
>> Good Suggestion. Will investigate that initially.
>
> Ok. Here is the funky bits. Me and Alin Dreghiciu have both been
> looking at different problems today(!) turning out to be the same
> thing.
>
> Craig, if you took the time to try out Equinox, you would probably
> find that it might work in Equinox (the Spring case does), but not in
> Felix and not in Knopflerfish... Why?
>
> Log4J (as Spring in Alin's case) try to use the thread context
> classloader, if one is present, otherwise use the classloader of
> "itself". Hence we are seeing the Webapp classloader being used in
> Log4J's loading of resources, resulting in terrible mismatches.
> So why does it work in Equinox. Equinox sets the thread context
> classloader to something they call ContextFinder, which will look at
> the call stack, and take the first classloader found other than system
> CL, which would be the classloader of Pax Logging Service in your
> case.
>
> So, depending on how you are setting this up, you need to do
> "something", like either replicate the ContextFinder approach, or
> plainly set the TCL to null prior to loading up Felix.

Is that something pax logging can do?

> I would be interested to hear if that helps. Also Many Thanks to Karl
> who provided a 'short-cut', as the TCL was not the first thing on my
> mind.

Well, it was the only thing left before considering it a framework bug
- I'm lazy :-)

regards,

Karl

> Cheers
> Niclas
>



-- 
Karl Pauls
karlpauls@gmail.com

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