Re: Jim Fulton : Extensible compound statements -- new exec flavor

Bill Janssen (janssen@parc.xerox.com)
Wed, 8 Feb 1995 20:17:05 PST

Excerpts from ext.python: 8-Feb-95 Re: Jim Fulton : Extensible.. Marc
Wachowitz@ipx2.rz.u (1620)

> > (I remember a message from Bill Janssen announcing a malloc-replacing
> > GC with finalization support -- anyone got time to look into that?)

> I'd guess that's a conservative collector. Is that going to work on for a
> non-Unix implementation of Python (I don't care personally, but ... ;-) ?

That's the Boehm-Demers-Weiser conservative garbage collector (see
ftp://ftp.parc.xerox.com/pub/gc/gc.html for details). It contains ports
for many platforms; from gc.html file: ``The collector is not
completely portable, but the distribution includes ports to most
standard PC and UNIX platforms. (Win32, win32s, OS/2, and UNIX
environments are supported on Intel-based PCs, as are all common UNIX
workstations, MacOS, and AmigaDOS.'' It contains a variety of
interesting access points.

But my opinion on this has ``grown'' since I originally made that
suggestion; I now believe that Python should be hosted on top of PARC
``PPCR''. Here's the abstract (from
ftp://ftp.parc.xerox.com/pub/ppcr/v1.20/README): ``The Posix Portable
Common Runtime (PPCR) provides integrated user-level support for
pre-emptive lightweight threads, garbage collected storage, and dynamic
programming loading. It should run on any POSIX.1-conforming
implementation that also supports BSD select() or System V poll(). PPCR
can take advantage of kernel thread extensions of the underlying system,
such as the LWP facility of Solaris 2.3 and the sproc facility of Irix
5, to achieve true concurrent execution by its threads on
multiprocessors. It also uses memory protection features available in
some systems (e.g. mprotect()) to support incremental garbage
collection.''

Bill