Re: Illegal C++

[Han-Wen Nienhuys]

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Wiz Aus wrote:
> > > Um...lilypond uses an interpretive language (Scheme), goes via TEX 
> > > and PS to produce output, and you're worried about a few extra C++ 
> > > function calls?  I would be flabbergasted if this made any measurable 
> > > difference to lilypond's performance.
> >
> > Actually, the optimization was pretty trivial once I had the 
> > precomputed methods going. FWIW, the top of the profile shows a lot of 
> > these "lowlevel" function calls that take a large amount of total 
> > execution time because of how often they are called.
> Ok, I just download the typeset of Beethoven's 7th symphony, 2nd 
> movement from www.mutopiaproject.com, and lilypond took a rather 
> languorous 2.5 minutes to produce a PDF!
> What would it have been *before* the optimizations?  

I don't know for sure. Try 2.6 if you want numbers.  The major 
optimization was actually reconfiguring some memory management 
parameters, which saved 30 to 40%. Most other optimizations were in the 
order of 2 to 5 %.

> I would expect 10 
> seconds absolute tops, and realistically, I would want to be able to 
> edit a score of this size (if not longer) and see my changes instantly - 
> i.e., subsecond output re-generation.  Obviously "regeneration" can 
> generally usually be done faster than generation from scratch (via 
> caching etc.), but 2.5 minutes seems kinda crazy.

I agree that it would be nice. If you have a constructive idea how we 
can do this, I'd be glad to hear about it.

> On top of this, the actual score produced is well...um...let's say "a 
> nice looking rough draft" - I'm not sure how much lilypond itself is to 
> blame (as opposed to the typesetter), but the score looks fairly free of 
> overrides and adjustments, so I was kinda surprised to see text 
> overlapping slurs and hairpins, 

I'm not claiming that Lily produces perfect output.  Better collision 
detection is on our radar, but the 2.7 series seems to be focused on 
page layout. Also, solving collisions algorithmically is tricky. For 
every case that you do correctly, there are also cases where the 
algorithm will make a bigger mess.

--
 Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen