Re: [Xsltforms-support] getting your feet wet with the profiler (was Re: optimization question)

[Alain C. <ala...@ag...>]

Kurt,

I'm not sure I understand correctly. Is it that, when clicking on the 
Profiler button, you have to wait a very long time especially on Chrome 
with which once you got an alert about a Javascript execution overload??

Thanks!

-Alain

Le 13/12/2011 17:30, Kurt Cagle a écrit :
> Alain,
>
> I too like the profiler, though I'm a bit distressed with the overall 
> download time for the package - on Firefox it's long but acceptable, 
> but on Chrome it seems to take forever to load (it times out at least 
> once).
>
> Kurt Cagle
> Invited Expert, XForms Working Group, W3C
> Managing Editor, XMLToday.org
> kur...@gm... <mailto:kur...@gm...>
> 443-837-8725
>
>
>
>
> On Fri, Dec 9, 2011 at 4:09 PM, Alain Couthures 
> <ala...@ag... <mailto:ala...@ag...>> 
> wrote:
>
>     Wow! What an impressive Christmas gift for XML fans!
>
>     You're absolutely right about the Profiler I added to XSLTForms:
>     it's a
>     wonderful tool to locate time-costing XPath expressions and refreshes.
>
>     In the latest builds, the Profiler is even a form: this means that it
>     can be customized by authors themselves. The profiling data is
>     collected
>     as an XML document and a specific processing-instruction tells
>     XSLTForms
>     which form to associate with.
>
>     I plan to add more information in the Profiler instance (instances
>     copies, the calling form source, ...): the Profiler will progressively
>     become a real XForms Debugger written in XForms.
>
>     About your form performance, I already suspected that counting
>     preceding
>     siblings would cost a lot of time: Javascript doesn't like loops
>     (XSLTForms has to have its own XPath machine written in
>     Javascript... I
>     proposed a paper for XML Prague 2012 about how to write an XQuery
>     compiler into Javascript instructions). I recently added support
>     for the
>     id() function and it's even much better for performance.
>
>     Defining a subform is now another possibility to simplify a form. This
>     is not yet documented but I already love it much. Don't hesitate
>     to ask
>     me about subforms if you're interested in.
>
>     If you want to load another form in a new browser tab from an instance
>     without server exchanges, defining an extra parameter for the load
>     action should be simple with the processing-instruction capability I
>     already use for the Profiler (this processing-instruction mechanism is
>     very promising indeed, I'm currently building a small XRAP
>     (XForms-REST-Apache-PHP) application with minimal generic PHP scripts,
>     XML files and folders on server).
>
>     XML allows us to consider programs as data. We might not be
>     numerous to
>     envision this (but the community is strong) and I have to confess that
>     I'm still marveled by this.
>
>     Thank you very much for your feedbacks!
>
>     -Alain
>
>     Le 09/12/2011 02:41, C. M. Sperberg-McQueen a écrit :
>     > Just a short report, for the record, of my experience with the
>     profiler
>     > now built into XSLTForms.
>     >
>     > Short version:  the profiler is very helpful; in this case three
>     relatively
>     > simple changes produced a five-fold speedup in the form.
>     >
>     > Long version:
>     >
>     > Looking at the profile information for the form I was worrying
>     about,
>     > which had gotten too slow when the document it was operating on got
>     > bigger, I found that the most expensive XPath expressions were those
>     > used for numbering the cells of the stack and for numbering the
>     > instructions in the code area.  I hard-coded appropriate numbers
>     into
>     > attributes in the machine description, and I added a set of
>     actions for
>     > adding a numbering attribute to the instructions in a program, after
>     > loading it. I then replaced each XPath expression of the form
>     > count(preceding-sibling::cell) +1 or count(preceding-sibling::i)
>     with
>     > a reference to @n.  I also removed the support for editing the
>     program
>     > code; I'll move it to a separate form which communicates with the
>     > main form by bouncing the XML representation of the document off
>     > of a routine on the server.
>     >
>     > The first two changes (prenumbering the stack cells and
>     autonumbering
>     > the instructions in the program) reduced the XForms Cumulative
>     Refresh
>     > Time after loading a program and stepping through 50 cycles of
>     machine
>     > time (i.e. clicking Step 50 times) from 94.6 seconds to 42.3
>     seconds,
>     > making the program about twice as fast.
>     >
>     > The third change (removing the editing functionality to a
>     separate form)
>     > took it down to 17.7 seconds, another twofold speedup, for a
>     five-fold
>     > speedup overall.
>     >
>     > Those who are curious can compare the timings and the subjective
>     > experience of the form by looking at the old and new versions of the
>     > form at
>     >
>     > http://blackmesatech.com/2011/12/pl0/v01.xhtml (old)
>     > http://blackmesatech.com/2011/12/pl0/index.xhtml (new)
>     >
>     > (Hmm.  I notice that the XSLTforms I'm using on that server is
>     > an old version that doesn't yet have the profiler.  I'll have to
>     update soon.)
>     >
>
>
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