FYI: https://github.com/open-mpi/ompi/issues/5798 brought up what may be the
same issue.
> On Oct 2, 2018, at 3:16 AM, Gilles Gouaillardet <gil...@rist.or.jp> wrote:
>
> Folks,
>
>
> When running a simple helloworld program on OS X, we can end up with the
> following error message
>
>
> A system call failed during shared memory initialization that should
> not have. It is likely that your MPI job will now either abort or
> experience performance degradation.
>
> Local host: c7.kmc.kobe.rist.or.jp
> System call: unlink(2)
> /tmp/ompi.c7.1000/pid.23376/1/vader_segment.c7.17d80001.54
> Error: No such file or directory (errno 2)
>
>
> the error does not occur on linux by default since the vader segment is in
> /dev/shm by default.
>
> the patch below can be used to evidence the issue on linux
>
>
> diff --git a/opal/mca/btl/vader/btl_vader_component.c
> b/opal/mca/btl/vader/btl_vader_component.c
> index 115bceb..80fec05 100644
> --- a/opal/mca/btl/vader/btl_vader_component.c
> +++ b/opal/mca/btl/vader/btl_vader_component.c
> @@ -204,7 +204,7 @@ static int mca_btl_vader_component_register (void)
> OPAL_INFO_LVL_3,
> MCA_BASE_VAR_SCOPE_GROUP, &mca_btl_vader_component.single_copy_mechanism);
> OBJ_RELEASE(new_enum);
>
> - if (0 == access ("/dev/shm", W_OK)) {
> + if (0 && 0 == access ("/dev/shm", W_OK)) {
> mca_btl_vader_component.backing_directory = "/dev/shm";
> } else {
> mca_btl_vader_component.backing_directory =
> opal_process_info.job_session_dir;
>
>
> From my analysis, here is what happens :
>
> - each rank is supposed to have its own vader_segment unlinked by btl/vader
> in vader_finalize().
>
> - but this file might have already been destroyed by an other task in
> orte_ess_base_app_finalize()
>
> if (NULL == opal_pmix.register_cleanup) {
> orte_session_dir_finalize(ORTE_PROC_MY_NAME);
> }
>
> *all* the tasks end up removing
> opal_os_dirpath_destroy("/tmp/ompi.c7.1000/pid.23941/1")
>
>
> I am not really sure about the best way to fix this.
>
> - one option is to perform an intra node barrier in vader_finalize()
>
> - an other option would be to implement an opal_pmix.register_cleanup
>
>
> Any thoughts ?
>
>
> Cheers,
>
>
> Gilles
>
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--
Jeff Squyres
jsquy...@cisco.com
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