On 01/15/15 15:34, Nathaniel Smith wrote:
On Thu, Jan 15, 2015 at 9:04 PM, Jeff Law <l...@redhat.com> wrote:
Stage3 is closing rapidly. I've drained my queue of patches I was tracking
for gcc-5. However, note that I don't track everything. If it's a patch
for a backend, language other than C or seemingly has another maintainer
that's engaged in review, then I haven't been tracking the patch.
So this is my final call for patch pings. I've got some bandwidth and may
be able to look at a few patches that have otherwise stalled.
I've been pinging this for about a year now in case it's of interest:
https://gcc.gnu.org/ml/gcc-patches/2014-10/msg01871.html
It fixes a show-stopper for using GOMP in libraries -- currently you
cannot use GOMP in any code where you don't control the whole program,
b/c it breaks fork(). (GOMP is the only OMP implementation that has
this problem.) This is particularly annoying for Python, since it
manifests as person A writing a fancy numerical package that happens
to use OMP internally (b/c they don't know any better), and then
person B trying to use Python's standard 'multiprocessing' library and
getting weird hangs and having no idea why.
Jakub, myself and management have discussed this issue extensively and
those patches specifically. I'm painfully aware of how this affects the
ability to utilize numerical packages in Python.
The fundamental problem is you're penalizing conformant code to make
non-conformant code work. In the last iteration I think the problem was
major memory leakage and nobody could see a way to avoid that.
It's highly unfortunate that posix, openmp, etc haven't tackled any of
the composability problems yet. I heard rumblings that those issues
were going to be investigated by openmp back in 2013, but I don't think
any significant progress has been made.
I don't see any way any of those patches are going to get in.
jeff
