[PD] audio drop-outs when resizing tables??

Miller Puckette mpuckett at imusic1.ucsd.edu
Sun Aug 19 20:09:51 CEST 2007

Resizing large memory objects in a real-time thread can block as the
OS pages other memory out to disk... so the operation is never safe
unless done in a separate thread.  This would be a major change, and
would move in the direction of making Pd harder to maintain in the long

Fixing the tabread~ object to do a double dereference would fix the problem
in 99% of cases... which is just the wrong thing to do if you want to be
able to use software on stage :)


On Sun, Aug 19, 2007 at 02:27:43PM +0200, Tim Blechmann wrote:
> On Sun, 2007-08-19 at 13:53 +0200, Matteo Sisti Sette wrote:
> > >> Does PD recompute the whole DSP chain whenever a table (with one or
> > more
> > >> tabread~ reading from it) is resized?
> > >
> > >yes, the dsp chain is recreated ...
> > 
> > Why does it need to recompute the dsp graph?
> > 
> > I know nothing about pd internals, but (or should I say "so") I really
> > can't 
> > see the reason for recomputing the dsp graph after resizing a table.
> don't ask me, ask miller (imho, this is one of the big design faults of
> pd).
> i can only guess, that it is done due to performance reasons ... it
> saves one pointer dereferencing. this is of course not a real
> explanation, as it is perfectly possible to keep track of the pointers
> in the dsp chain ... neither is it that expensive to do an additional
> pointer dereferencing ...
> > It seems it does not even recompute it when you send a
> > [set ...( message to 
> > a tabread~ (at least I get no dropouts)... why do it when you resize
> > a 
> > table? 
> that is the other direction ... when objects are bound to the table,
> then they can just call garray_getfloatarray ... if tables change,
> garray_getfloatarray has to be called from all objects, that are bound
> to this table ...
> cheers, tim
> --
> tim at klingt.org    ICQ: 96771783
> http://tim.klingt.org
> I had nothing to offer anybody except my own confusion
>   Jack Kerouac

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