On 11-nov-10, at 20:10, Russel Winder wrote:
On Thu, 2010-11-11 at 18:24 +0100, Tobias Pfaff wrote:
[ . . . ]
Unfortunately I only know about the standard stuff, OpenMP/OpenCL...
Speaking of which: Are there any attempts to support lightweight
multithreading in D, that is, something like OpenMP ?
I'd hardly call OpenMP lightweight. I agree that as a meta-notation
for
directing the compiler how to insert appropriate code to force
multithreading of certain classes of code, using OpenMP generally
beats
manual coding of the threads. But OpenMP is very Fortran oriented
even
though it can be useful for C, and indeed C++ as well.
However, given things like Threading Building Blocks (TBB) and the
functional programming inspired techniques used by Chapel, OpenMP
increasingly looks like a "hack" rather than a solution.
I agree I think that TBB offers primitives for many parallelization
kinds, and is more clean and flexible than OpenMP, but in my opinion
it has a big weakness: it cannot cope well with independent tasks.
Coping well wit both nested parallelism and independent tasks is a
crucial thing to have a generic solution that can be applied to
several problems.
This is missing as far as I know also from Chapel.
I think that having a solution that copes well with both nested
parallelism and independent tasks is an excellent starting on which to
build almost all other higher level parallelization schemes.
It is important to handle this centrally, because the number of
threads that one should spawn should ideally stay limited to the
number of execution units.
