[Python-3000] Delayed reference counting idea

[Ronald Oussoren]

On Sep 18, 2006, at 9:56 PM, Raymond Hettinger wrote:

>
> * I doubt the anecdotal comments about Boehm GC with respect to
> performance.  It may be better or it may be worse.  While I think the
> latter is more likely, only an implementation patch will tell the  
> tale.

hear, hear ;-). Other anecdotical evidence says that a GC can be  
significantly faster than manual allocation, especially a copying  
collector where allocation can be really, really cheap. Boehm's GC  
isn't a copying collector, but I wouldn't count it out just because  
"everybody knows that GC is slow".

I'd be more worried about changes in semantics, it's pretty  
convenient to write 'open(somefile, 'r').read()' to read a file in  
bulk, currently this will immediately close the file but with a GC  
system it may be a long time before the file is actually closed.

Another reason to be scared of GC is some bad experience I've had  
with Java's GC, its rather annoying if you're a sysadmin, get a Java  
app thrown over the wall and then have to tweak obscure GC-related  
parameters to get decent performance (or rather, an application that  
doesn't crash after running for a couple of days). That may have been  
bad code in the application, but I'm not entirely convinced that  
Java's GC doesn't deserve to get some of the blame.

Ronald
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