Re: threads and shared interpreter data structures

[Elizabeth Mattijsen]

Please note that these are comments from a Parrot list lurker and 
outsider, but also as someone with some hands on experience with Perl 
threads...  ;-)   And probably stating the bleedingly obvious.

At 11:09 +0100 12/21/03, Leopold Toetsch wrote:
 *If* ParrotClasses are per thread (very likely yes - different 
threads might create different objects of different classes 
dynamically) *and if* Parrot_class_register() creates entries in 
Parrot_base_vtables[], then this structure has to be per interpreter 
too.
I agree.

Ideally I'd see a COWed structure: a thread startup would not 
actually copy the main vtable structure.  As soon as something needs 
to be specific for the thread, only then needs that structure to be 
copied for the thread (and possibly only that part that is actually 
different from the thread a thread is inheriting from.

The main problem with Perl 5 ithreads is the thread startup CPU and 
memory usage.  It's what makes Perl 5 ithreads _very_ hard to use in 
a production environment.  That overhead needs to be prevented at all 
costs in Parrot.

Hope this made sense.

Liz