Resolve the Issue

Hi Michael,

We have found a suitable work around
for the issue. We have replaced the NodeList implementation which
surely is not  thread safe due to the caching mechanism built in it.


We implemented "NodeList"
using "Node"

The "for" loop is replaced
by "while" loop as follows:-
First Element - Node's getFirstChild
method
Next Element - Node's getNextSibling
method
End of Iteration- Null is obtained when
getNextSibling is used.

We have tested at our end and it worked
fine. This might be a good alternative implementation for NodeList.

In this solution there is no  SLA
impact , this solution is does not have any synchronization. 

Please suggest if you find any potential
problem in this work around.

Soumya Chatterjee
Tata Consultancy Services
Mailto: soumya.chatterjee@xxxxxxx
Website: http://www.tcs.com
____________________________________________
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Michael Glavassevich <mrglavas@xxxxxxxxxx>

07/24/2007 07:27 PM

To	Soumya Chatterjee <soumya.chatterjee@xxxxxxx>
cc	j-users@xxxxxxxxxxxxxxxxx
Subject	Re: Got the Issue

Hi Soumya,

Xerces' DOM implementation isn't thread-safe. If you try to access the
same DOM instance from multiple threads without synchronizing it you'll
run into these problems. You either need to synchronize your code or 
create an instance of the DOM tree per thread. There's really no way 
around it.

Thanks.

Michael Glavassevich
XML Parser Development
IBM Toronto Lab
E-mail: mrglavas@xxxxxxxxxx
E-mail: mrglavas@xxxxxxxxxx

Soumya Chatterjee <soumya.chatterjee@xxxxxxx> wrote on 07/24/2007
09:42:08 
AM:
 
> Hi Michael, 
> 
> I found out the response from you regarding the "xerces DOM 
> concurrent access" and I think it is the same as our application
in 
> the case.  http://spteam-lists.blogspot.com/2007/04/re-xerces-dom-
> concurrent-access-and.html 
> 
> By the way we were not getting the exception as frequently  in
the 
> weblogic 7.1 ( JDK 1.3) when we are using the following Xerces.
> 
> But we are getting the exception in case of weblogic 9.1 much more
> frequently which uses JDK1.5 and different version of Xerces. 
> 
> Synchronization is not an option in this case because there is a 
> huge performance issue here. Please let me know if any way we can
> get read of this problem without using the Synchronization  block.
> 
> Thanks,
> Soumya Chatterjee
> Tata Consultancy Services
> Mailto: soumya.chatterjee@xxxxxxx
> Website: http://www.tcs.com
> ____________________________________________
> Experience certainty.        IT Services
>                    
   Business Solutions
>                    
   Outsourcing
> ____________________________________________

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