On Mon, Oct 5, 2015 at 2:52 PM, Sturla Molden <sturla.mol...@gmail.com> wrote: > On 02/10/15 13:05, Daπid wrote: > >> Have you tried asking Python-dev for help with this? Hopefully they >> would have some weight there. > > It seems both GCC dev and Apple (for GCD and Accelerate) has taken a similar > stance on this. There is tiny set of functions the POSIX standard demands > should work on both sides of a fork without exec, but OpenMP, GCD, BLAS or > LAPAPCK are not included. As long as there is no bug, it is hard to convince > them to follow Intel and allow fork-based multiprocessing.
To be clear, the GCC devs are open to supporting fork+OpenMP in principle, they just aren't willing to do it in a way that risks breaking strict POSIX or OpenMP compatibility. But that isn't even the problem -- we have a patch that is strictly compatible with POSIX and OpenMP. The problem is that with the patch, the cases that would formerly have deadlocked instead leak some memory. This is not a big deal IMO for a variety of reasons (mostly that a one time leak per child process is tiny, esp. compared to the current situation with deadlocks), but it means the patch needs someone serious in the GCC community to take a look at it carefully, understand what the tradeoffs actually are, and make a judgement call. And so far we haven't convinced anyone to do this. -n -- Nathaniel J. Smith -- http://vorpus.org _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org https://mail.scipy.org/mailman/listinfo/numpy-discussion
