Potential reuse of TagHandlers implementing JspIdConsumer?

[Jochen Wuttke <wu...@lu.unisi.ch>]

Hi,

for my research project I've been doing some ApsectJ magic with Tomcat  
and deployed WebApps. Among other things I'm interested in detecting  
at runtime when TagHandlers instantiated in a HttpServlet go out of  
scope. Since that can't be done with AspectJ I was tracking garbage  
collection to see when the objects get removed. To be sure that that  
made some sense I looked at where the servlet code instantiates the  
TagHandlers, and since they are created and used as local variables, I  
was expecting them to be collected after the servlet finishes  
processing.
Unfortunately, a few experiments showed that that is not the case.   
After delving into the details of the servlet code generated for JSP  
pages I discovered that the methods instantiating TagHandlers also  
store them in TagHandlerPools using #reuse().
I'm doing my experiments with a demo application for Java Server  
Faces, and all JSF tag handler implement  
javax.servlet.jsp.tagext.JspIdConsumer. The spec says that handler  
implementing that interface may not be reused, so I was wondering if  
this is a potential bug or if I'm missing some intricate detail of how  
things work.

Thanks,
Jochen

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Re: Potential reuse of TagHandlers implementing JspIdConsumer?

[Christopher Schultz <ch...@christopherschultz.net>]

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Jochen,

I'd definitely like to know the answer to this, too. Replying to bump
the topic.

- -chris

Jochen Wuttke wrote:
> Hi,
> 
> for my research project I've been doing some ApsectJ magic with Tomcat
> and deployed WebApps. Among other things I'm interested in detecting at
> runtime when TagHandlers instantiated in a HttpServlet go out of scope.
> Since that can't be done with AspectJ I was tracking garbage collection
> to see when the objects get removed. To be sure that that made some
> sense I looked at where the servlet code instantiates the TagHandlers,
> and since they are created and used as local variables, I was expecting
> them to be collected after the servlet finishes processing.
> Unfortunately, a few experiments showed that that is not the case. 
> After delving into the details of the servlet code generated for JSP
> pages I discovered that the methods instantiating TagHandlers also store
> them in TagHandlerPools using #reuse().
> I'm doing my experiments with a demo application for Java Server Faces,
> and all JSF tag handler implement
> javax.servlet.jsp.tagext.JspIdConsumer. The spec says that handler
> implementing that interface may not be reused, so I was wondering if
> this is a potential bug or if I'm missing some intricate detail of how
> things work.
> 
> Thanks,
> Jochen
> 
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> To start a new topic, e-mail: users@tomcat.apache.org
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
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