[Python-ideas] Exploration PEP : Concurrency for moderately massive (4 to 32 cores) multi-core architectures

[Jim Jewett]

On 9/18/07, Brian Granger <ellisonbg.net at gmail.com> wrote:

> If there were infinitely many people willing for work on this stuff,
> then I agree, but I don't see even a dozen people hacking on the GIL.

In part because many people don't believe it would be productive.

For threading to be useful in terms of parallel processing, most
memory access has to be read-only.  That isn't true today, largely
because of reference counts.

There are ways around that, by using indirection, or delayed counts,
or multiple refcount buckets per object, or even just switching to a
tracing GC.

So far, no one has been able to make these changes without seriously
mangling the C API and/or slowing things down a lot.  The current
refcount mechanism is so lightweight that it isn't clear this would
even be possible.  (With 4 or more cores dedicated to just python, it
might be worth it anyhow -- but it isn't yet.)  So if you want the GIL
removed, you need to provide an existence proof that (CPython) memory
management can be handled efficiently without it.

-jJ