[pypy-dev] STM

Armin Rigo arigo at tunes.org
Mon Jan 9 14:03:18 CET 2012


Hi Andrew,

On Sun, Jan 8, 2012 at 21:24, Andrew Francis <andrewfr_ice at yahoo.com> wrote:
> A silly question? What is the paper you are discussing?

The Problem with Threads, Edward A. Lee, EECS 2006.

> Perhaps this is off-topic, in  non-trivial stackless programme using
> cooperative scheduling, unless you explicitly impose a logical ordering, it is difficult to predict
> when a particular tasklet will  run. The round-robin doesn't mean much.

Ok, so basically no real Stackless program relies on a particular
order anyway.  This is in line with what I expected.

> If I understand what you are proposing, the problem I see with yielding in
> the coarse-grained tasklet-as-transaction, is that you probably need more
> machinery to ensure ACID properties, since you are now getting thread
> interweaving and potential race conditions.

Yes, and this machinery is exactly what STM libraries offer.  Given
that you have multiple transactions that can *mostly* occur in
parallel, STM ensures that in *all* cases, it will look like the
transactions have been run serially, while actually performing them in
parallel under the hood.


A bientôt,

Armin.


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