[texworks] CPU 100% when viewing pdf

[Stefan Löffler]

Hi,

Am 2010-06-29 01:48, schrieb kap4lin:
> After some more digging around, there seems to be a problem in
> displaying the proper page size as requested by the geometry package.
>   

This is very interesting indeed. Though not completely improbable. If
poppler gets the page size wrong somehow it will naturally run into
problems while rendering. But this is just speculation...

> On Mon, Jun 28, 2010 at 1:22 AM, Stefan Löffler <st.loeffler at gmail.com> wrote:
>   
>> Am 2010-06-27 21:39, schrieb kap4lin:
>>     
>>> On Fri, Jun 25, 2010 at 10:04 PM, kap4lin <kap4lin at gmail.com> wrote:
>>>
>>>       
>>>> I updated TeXworks to the current r663 version and "hell broke loose."
>>>> The CPU usage is 100% when a pdf file is opened. And Tw just stops
>>>> working. I have to kill the process. But no problems when just a tex
>>>> file is opened. Essentially, it is unusable now!
>>>>
>>>>         
>>  * Does this happen with all pdfs, even simple "Hello World" ones?
>>     
> Yes, whenever something other than "letterpaper" is set as the page
> size. I've attached a tex file - it has three cases, of which the
> third one (a4paper) creates problem. I'll be referring to these cases
> in this reply. Of course, a5paper or a3paper also create the same
> problem.
>   

Hm... cases 2 and 3 worked fine for me (I didn't go on to test case 1)
on Ubuntu 10.04 Linux with TL2009 and Tw r663. Could you also send a
problematic pdf file (in case it's a problem during typesetting)?

> The status quo, in all the 8 following cases, is this: Case 3: 100%
> cpu, Cases 1,2: fine
>
> Tw r649 + Qt 4.5.3 + poppler 0.12.2
> Tw r649 + Qt 4.5.3 + poppler 0.14.0
> Tw r649 + Qt 4.6.3 + poppler 0.12.2
> Tw r649 + Qt 4.6.3 + poppler 0.14.0
>
> Tw r663 + Qt 4.5.3 + poppler 0.12.2
> Tw r663 + Qt 4.5.3 + poppler 0.14.0
> Tw r663 + Qt 4.6.3 + poppler 0.12.2
> Tw r663 + Qt 4.6.3 + poppler 0.14.0
>   

Thanks for this quite extensive list!

> As you might have guessed. There is some interaction with the page
> size display. pdflatex compiles fine and both kpdf (from kde 3.5) and
> acroread can open hello_world.pdf in all three Cases. Looking under
> File > Properties in acroread shows the correct page dimensions as
> specified using \usepackage[...]{geometry} which implies that
> pdflatex's compilation is fine.
>   

I don't know what underlying pdf engine kpdf uses, but acroread
certainly uses a self-made one. Could you try in Okular (it's kde-based,
AFAIK) or some other poppler-based application (see
http://freedesktop.org/wiki/Software/poppler) to see how they react to
your files?

> Btw, is there any benefit in Qt 4.6.3 from Tw's point of view?
>   

>From Tw's POV, I'd say no. AFAIK, Tw doesn't use any particular features
of Qt 4.6 (we're still aiming at compatibility with 4.3). But it
probably has many bugfixes and enhancements, so it's probably not a bad
idea to update.

> In the meanwhile, I've tested Tw r663 on some of my actual documents
> which either don't have any paper specification or has letterpaper
> specified. And everything works fine.
>
> So, after all this, is it a poppler issue?
>
> FWIW, my TL installation was done by opting for letter instead of a4
> and 'tlmgr paper' shows all paper sizes as letter.
>   

It's exactly the reverse for me. Being Europe-based, everything's a4 for
me ;), but I haven't experienced any problem so far. So yes, this may be
a poppler issue.

HTH
Stefan