[PD] Segmented Patch Chords? PVar / PV?

[Mathieu Bouchard]

On Tue, 14 Feb 2006, Roman Haefeli wrote:

> "Mathieu Bouchard" <matju at artengine.ca> wrote:
> > > $0-send/receive: what would be the difference to a NOT-fake-mechanism?
> > Avoiding pollution of the symbol-table?
> this topic has been mentioned already a few times on this list, but suddenly i
> still don't know what this means exactly. does pollution mean, that the
> symbol-table uses a lot of ram? does that have any bad effects on performance?
> is there a good way to avoid pollution (i mean when patching) ?

Pd starts up with a fixed-size symbol-table. This is a big array of
symbols. If the table becomes full (or even just crowded) there are more
and more symbols that share the same cell in the symbol-table by chaining
one symbol to another. Long chains of symbols are slow. If you use many
symbols, the quick fix is to increase the size of the table but to do 
that you need to recompile pd.

Most of the problem of having many symbols comes from the fact that most
symbols have two parts, because they're made like $0-foo where $0 is some
integer. There's no quick escape from that. Pd needs a new atom type for
local symbols. When it gets it, all externals would have to be updated in 
order to support it.

The other main cause of symbol pollution is that pd doesn't have text
strings. Strings can be deallocated, while symbols are æternal, that is,
until you quit pd. If you use pd for heavy string processing in an art
installation, make sure you do scheduled shutdowns in order to prevent
swapping, thrashing and crashing; make tests and extrapolations to figure 
out when it would have used all of your RAM, etc.

 _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada