Re: [xml-dev] Using XML (or JSON) for inter-thread communication

[Mike Sokolov <sokolov@ifactory.com>]

We have use case where we need to see the results of documents processed 
earlier in our pipeline, but in a parallel processing environment they 
may not have finished writing yet.  In a single xslt we are mostly 
protected from this since the results of doc() and other external 
sources of input are required to be immutable, right?  But we supply our 
own functions that query external data sources and they (deliberately) 
break this contract.  And of course if you run multiple xslts in series, 
the results from the first one may show up in the second.  In cases like 
this you need to be careful about synchronizing, and it becomes 
important to introduce a barrier that waits for outstanding writes to 
complete.

I wonder if this sort of issue is being addressed in any way in the 
threading work you're doing in xslt?

-Mike

On 03/19/2012 01:43 PM, Michael Kay wrote:
>
>> I assume that under some circumstances it's possible to generate a 
>> number of fragments of an output document in parallel and then merge 
>> the fragments at the end of the operation.  If so, is XSLT 
>> functionalism sufficient to do that automatically, or would some 
>> external programmer input be required to implement that?
>>
>>
> Initially we're taking a cautious approach: using multithreading 
> automatically where we're pretty confident it will usually give a 
> benefit (xsl:result-document, fn:collection()) and allowing it to be 
> invoked manually in cases where we think it's likely to incur more 
> cost than benefit in a significant number of cases (xsl:for-each, 
> xsl:apply-templates). Hopefully the decision-making will become more 
> sophisticated as we gain experience and gather user feedback.
>
> Michael Kay
> Saxonica
>
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