Re: [Webmacro-devel] I'm actually working on WM :) A locking question...

[Marc P. <ma...@an...>]

On 9 Dec 2005, at 03:58, Eric B. Ridge wrote:


> I'm pretty pissed.  I spent about 30 minutes working on a response  
> this morning and somehow it has mysteriously disappeared.  I  
> thought I sent it, but I can find no trace of it in my Sent Items  
> nor on this list.  Maybe OS X isn't so easy to use afterall!
>
>

Hey I recently converted - got a Mac Mini and it rocks. I'm never  
going back!


> Anyways, here's the abridged version...
>
>
>> Once every time a not previously visited JSP page is compiled.
>>
>
> That's what I was expecting you to say.
>
>
>> So you see it's using the ServletContext which if memory serves  
>> correctly should be the same for every servlet... and yet we still  
>> get N "WebMacro initializing" log outputs.
>>
>
> Apparently this isn't true.  The "Servlet22Broker" class caches  
> instances in a central map key'd on ServletContext.  If you trace  
> through the code you'll eventually find that it stores  
> WeakReferences to the XXXBroker instances.
>
> So either each JSP is getting its own, unique ServletContext or the  
> WeakReferences are causing your previously-instantiated Broker  
> instances to be gc'd too quickly.  I'm betting on the former.  I  
> think ServletContext is per Servlet, not per "web-app".
>
> We've written our own servlet engine/webserver here at TCDI and  
> that's how we interpreted the jsdk spec.  Granted, our engine  
> doesn't do JSP's, but still, a JSP is just a Servlet.
>
>

Ah ok so it looks like there are different ServletContext instances,  
although they all provide the same data/services. Odd.


>> The problem is that we cannot instantiate WM until we have a JSP  
>> pageContext that is valid, as that is the only way we can get a  
>> ServletContext so that WM uses a ServletBroker.
>>
>
> Right, and that is what sucks about the various ServletBrokers.   
> Personally, I'd spend the extra time to construct a  
> WebMacro.properties file that knows how to load templates from the  
> same places as the ServletBrokers do.  The whole idea of storing  
> templates inside WEB-INF/ is, imho, just plain silly.  Put 'em in  
> your classpath (ie, in a .jar) or directly on the filesystem.
>
> If you do this, you'll be able to create ONE WM instance that all  
> your servlets and taglib instances can share.
>
>

I disagree, I think WEB-INF is a good place for templates, a JAR is  
yet another deployment hassle, putting them in WEB-INF/classes is  
just plain ugly.


>> I'm pretty sure we can work around this with a simple concurrent  
>> class - I just need to know which.
>>
>
> I think that's overkill and that you'd be happier with a non- 
> servlet-based WM instance.
>

Easier perhaps, but not happier :)

I'll work out a simple sync scheme somehow. Although if the Brokers  
are shared they are discrete instances anyway and it's not a huge  
overhead. It is annoying getting duplicate logging though.

~ ~ ~
Marc Palmer (ma...@an...)
Consultant/Analyst
AnyWare Ltd.
http://www.anyware.co.uk/