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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