Re: Sibelius Software UK office shuts down

[Tim Roberts]

George_ wrote:
> WRT (1): Someone in this thread suggested using individual threads to render
> a bar at a time. The end result would be messy, but what if one or two
> threads were dedicated to running 'behind' the main threads to clean up and
> knit together output?

Multithreading works well when there are "natural" subdivisions of the
work.  It's really hard to come up with a "natural" subdivision for
Lilypond.  Bars are not particularly fundamental to Lilypond music.  Bar
lines are just another thing that get engraved.  Plus, Lilypond does not
require that all staves in a system have the same bar structure. 
Dividing into systems would be convenient, but you don't really know
where the next system starts until you're done with the current one.

Having done quite a lot of threaded programming, when I think of the job
Lilypond is doing, I don't see any natural breakdown.  It's a very
sequential process.

Now, it might be possible to have one thread producing an internal
representation of the score -- kind of an intermediate language -- and
have another thread sucking on that representation and blowing PDF or
EPS or MIDI or whatever.  Even that would only be possible if the
internal representation did not change fundamentally after it was
created.  When I see status messages that say, for example "fitting
music onto 4 or 5 pages", that leads me to believe that there is "global
optimization" going on that might go back and move things on earlier pages.

-- 
Tim Roberts, address@hidden
Providenza & Boekelheide, Inc.