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From Davanum Srinivas <d...@yahoo.com>
Subject Re: Strange problems with concurrent access of Xalan-2.0.0
Date Thu, 15 Feb 2001 21:14:40 GMT
Giacomo,

> Wait a second I'll try to do a stress test using ab....
>     ab -c 20 -n 200 http://localhost:8080/cocoon/welcome  

Where can i download this utility from?

Thanks,
dims

--- Giacomo Pati <giacomo@apache.org> wrote:
> Carsten Ziegeler wrote:
> > Hello,
> >
> > since the switch from the Xalan2D07 to the Xalan-2.0.0 version in Cocoon2
> > we get sometimes very strange problems.
> >
> > We are using frames which all four use the same stylesheets. The xalan is
> > driven by the cocoon pipeline.
> >
> > If we turn on the storing (formerly known as caching) of the
> > TraxTransformer we get from time to time a NPE in one frame. Sometimes its
> > even worse: One frame contains part of the content of another frame and the
> > other frame is totally broken. Reloading the whole page brings up all
> > frames correctly.
> >
> > However if we turn off the storing we never did see this phenomenen. So we
> > assume that this problems have something to do with the storing.
> >
> > The store stores the Templates. Is it possible, that this problem can
> > occure, when several threads use the same Template (as delivered by the
> > store). A thread might finish first, resetting the template and the other
> > thread still try to use it.
> 
> A Template IIRC should be thread safe but the actual transformation is done 
> by a Transformer object which can be obtained from the Template (or is it the 
> other way around?).
> 
> Wait a second I'll try to do a stress test using ab....
> 
>     ab -c 20 -n 200 http://localhost:8080/cocoon/welcome  
> 
> No, I can't reproduce the failure. All runs well here.
> 
> Any guesses from the Xalan Team?
> 
> Giacomo
> 
> >
> > This is only a guess - has someone else had these problems?
> >
> > As they only occur occasionally it his very hard to reproduce them...
> >
> > Perhaps someone of you has a guess whats going on.
> >
> > The exception we get is the following:
> >
> > java.lang.NullPointerException
> >         at org.apache.xalan.templates.ElemCopy.execute(ElemCopy.java:145)
> >         at
> > org.apache.xalan.templates.ElemForEach.transformSelectedNodes(ElemFor
> > Each.java:495)
> >         at
> > org.apache.xalan.templates.ElemApplyTemplates.execute(ElemApplyTempla
> > tes.java:193)
> >         at
> > org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Tr
> > ansformerImpl.java:2154)
> >         at
> > org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Tr
> > ansformerImpl.java:2097)
> >         at
> > org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(Tran
> > sformerImpl.java:2029)
> >         at
> > org.apache.xalan.transformer.TransformerImpl.transformNode(Transforme
> > rImpl.java:1189)
> >         at
> > org.apache.xalan.transformer.TransformerImpl.run(TransformerImpl.java
> >
> > :2894)
> >
> > This indicates that the ResultTreeHandler is not available (set to null).
> >
> > As most times everything is working fine it must have to do with the
> > parallel usage of the stylesheets.
> >
> >
> >
> > Carsten Ziegeler
> >
> > Open Source Group              sunShine - Lighting up e:Business
> > ================================================================
> > Carsten Ziegeler, S&N AG, Klingenderstrasse 5, D-33100 Paderborn
> > www.sundn.de                           mailto:cziegeler@sundn.de
> > ================================================================
> >
> >
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> 


=====
Davanum Srinivas, JNI-FAQ Manager
http://www.jGuru.com/faq/JNI

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