Hi Andrew, On Thu, Oct 24, 2013 at 8:27 PM, Andrew Francis <andrewfr_...@yahoo.com> wrote: > A bit more context - I have looked at the C code for the Go channel > implementation and said "wow, there is a lot of locking there"! I also have > been following conversations concerning race conditions and the race > detector (based on thread sanitizer) and asking myself: pypy-stm could do > this.
Precisely my point. You're coming with paper X describing Y and thinking "pypy-stm could do this", whereas I don't see any obvious connection between the two. To repeat myself, pypy-stm has no GIL internally, but exposes to the user semantics that are the same as a GIL Python. To be on the clear side, you could use CPython and write C, with GIL-releasing code around the complicated lock-free algorithm; but the point of the lock-free algorithm is to be very fast, negating the advantage of releasing the GIL in the first place. Is that correct? Then if you want to integrate it inside pypy-stm instead, it's more complicated than that: we don't want an algorithm (say a simple lock-free queue) without some behavior that is tailored to the stm world. For example, if you implement only a queue, then: - pops will appear out of order if they are done in some order but the transactions commit in a different orders; - pops will be lost if they are done by a transaction that aborts; - pushes must be at least delayed until the transaction commits, otherwise we see bogus data from other threads. So you need to think about it more deeply than just "pypy-stm is cool, let's use it for X". You can't just think about pypy-stm as a lock-free Python, because that's only half the truth. PyPy-stm is all about a special use of lock-free algorithms in order to give the user the illusion of the GIL. I would say that it's not really the correct ground to experiment with lock-free structures in general --- it's a place where we can experiment with custom adaptations of some lock-free structures, done towards a specific goal that makes sense for the user of pypy-stm. A bientôt, Armin. _______________________________________________ pypy-dev mailing list pypy-dev@python.org https://mail.python.org/mailman/listinfo/pypy-dev
