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

[Kurt C. <kur...@gm...>]

It may be something in the form rendering - the download of the XSLT file
takes very little time, but I'm looking at 15-20s before the form itself is
rendered in Chrome - compared to 2-3 for the October release which I had
been using. Firefox is faster, but not appreciably. This is being delivered
out of MarkLogic.

Kurt Cagle
Invited Expert, XForms Working Group, W3C
Managing Editor, XMLToday.org
kur...@gm...
443-837-8725




On Wed, Dec 14, 2011 at 3:11 PM, Alain Couthures <
ala...@ag...> wrote:

>  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...
> 443-837-8725
>
>
>
>
> On Fri, Dec 9, 2011 at 4:09 PM, Alain Couthures <
> 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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