On Thu, Mar 30, 2017 at 8:39 AM, Lawrence Mitchell < lawrence.mitchell@imperial.ac.uk> wrote:
On 30/03/17 14:28, Matthew Knepley wrote:
What is going on here? It looks like you are using subprocess. Why would you do that on a cluster rather than MPI?
It's all pretty icky. One of the JIT steps involves forking something. Plausibly, Henrik, your MPI doesn't like fork. I went round at one point to try and set up a single subprocess that was able to fork before MPI_Init.
For example, when using craypich, I need to say:
export MPICH_GNI_FORK_MODE=FULLCOPY
Old OpenMPI versions, especially those using some infiniband stuff, don't like fork either, for example https://www.open-mpi.org/faq/?category=openfabrics#ofa-fork
Matt, here is David's response (you're not subscribed I think, so didn't get it):
Is there a simple thing we can do to shut this off for testing? He is on a cluster I believe. Hendrik, do you know what MPI you are using? Thanks, Matt
Hi Matt,
Are you sure? To me it looks like pulp is using subprocess to fork the linear program solver. Nothing to do with parallel.
David
Lawrence
-- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener