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Re: Exploiting multi-core CPUs during XML parsing

• To: Sean McGrath <sean.mcgrath@p...>
• Subject: Re: Exploiting multi-core CPUs during XML parsing
• From: Wolfgang Hoschek <wolfgang.hoschek@m...>
• Date: Fri, 31 Mar 2006 23:33:40 -0800
• Cc: xml-dev@l...
• In-reply-to: <442E2A2A.1070003@p...>
• References: <442E2A2A.1070003@p...>

What kind of application would seriously benefit from this sort of  
fine-grained intra-task parallelism? Server apps typically runs many  
tasks concurrently, and so embarrasing parallelism is found naturally  
at more coarse grained levels, which is more cost effective. Plus,  
given that the algorithm is deviating from pure sequential access it  
might not even speed things up at all.

Wolfgang.

On Mar 31, 2006, at 11:22 PM, Sean McGrath wrote:

> I have sketched out an algorithm for fast XML WF parsing utilising  
> two threads that each start at opposite ends of the octet-stream  
> and meet in the middle. The algorithm hinges on the fact that  
> start- and end-tags are balanced. i.e. as one thread reads forward  
> looking for foo start-tag, the other thread is reading backwards  
> looking for foo end-tag.
>
> This also has the nice side effect of giving you accurate error  
> messages quickly. i.e. as soon as a mismatched tag is found, it can  
> be reported. This is particularly useful with recursive element types.
>
> Modern machines (even desktop boxes) will increasingly have multi- 
> core CPUs as standard and I think it behooves us to find ways of  
> exploiting that in the XML world.
>
> But to get the most out of the algorithm, you really need a  
> filesystem that supports reading byte-streams backwards.
>
> Does anyone know of such a filesystem?
>
> thanks,
> Sean
>
>
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• References:
  • Exploiting multi-core CPUs during XML parsing
    • From: Sean McGrath <sean.mcgrath@p...>

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