[jdom-interest] Performance: JDOM2 and Saxon

Michael Kay mike at saxonica.com
Tue Oct 25 06:19:53 PDT 2011

On 25/10/2011 13:26, Rolf Lear wrote:
> Excellent. I can work with that, and the feedback is appreciated.
> If nothing else, seeing the numbers creates something of a 'baseline'
> against which we can set expectations.
> Based on your response, and since you are the first 'users' of JDOM2
> speaking up (thanks) perhaps some follow-up comments:
> 1. the XPath area (org.jdom2.xpath.*) is expected to be revised still
> (issues #42 and #45). This may impact your work.
Well, apart from the comparative testing, we don't actually use that part
> 2. Have you identified any areas of JDOM2 code which are underperforming?
> You mention the "navigational API's" can you narrow that down to any
> particular iterators/methods?
I think that would need more careful study than we've carried out so 
far. But from what I've gleaned lurking on the list in the last couple 
of months, it wouldn't surprise me at all if namespaces are the culprit. 
They usually are.
> 3. In general is JDOM2 'better' to work with than JDOM1? Is it going in
> the right direction? Do you even notice it?
I don't think we'd have noticed it at all if we hadn't been deliberately 
exploring the way the descendant axis navigation is now done. To be 
honest, my main motivation was to see if there were any ideas here worth 
> 4. Are there any other changes that would make your life easier
> (API/etc.)?
> Well, apart from a total redesign to make it more strongly typed... The most tedious part is probably merging adjacent text nodes. I imagine that's a usability hazard for ordinary users too. Also, I suspect that sorting nodes into document order is probably more expensive than it needs to be.
Michael Kay

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