test/mpi: Add non-collective sessions init test

src/mpid/ch4/netmod/ofi/ofi_init.c

@@ -852,7 +852,7 @@ int MPIDI_OFI_mpi_finalize_hook(void)
         /* sockets provider need flush any last lightweight send. */
         mpi_errno = flush_send_queue();
         MPIR_ERR_CHECK(mpi_errno);
-    } else if (MPIR_CVAR_NO_COLLECTIVE_FINALIZE) {
+    } else if (!MPIR_Process.comm_world || MPIR_CVAR_NO_COLLECTIVE_FINALIZE) {
         /* skip collective work arounds */
     } else if (strcmp("verbs;ofi_rxm", MPIDI_OFI_global.prov_use[0]->fabric_attr->prov_name) == 0
                || strcmp("psm2", MPIDI_OFI_global.prov_use[0]->fabric_attr->prov_name) == 0

src/mpid/ch4/netmod/ucx/ucx_init.c

@@ -243,7 +243,7 @@ int MPIDI_UCX_mpi_finalize_hook(void)
     int n = MPIDI_UCX_global.num_vcis;
     pending = MPL_malloc(sizeof(ucs_status_ptr_t) * MPIR_Process.size * n * n, MPL_MEM_OTHER);
 
-    if (!MPIR_CVAR_NO_COLLECTIVE_FINALIZE) {
+    if (MPIR_Process.comm_world && !MPIR_CVAR_NO_COLLECTIVE_FINALIZE) {
         /* if some process are not present, the disconnect may timeout and give errors */
         mpi_errno = MPIR_pmi_barrier();
         MPIR_ERR_CHECK(mpi_errno);

test/mpi/.gitignore

@@ -1181,10 +1181,6 @@
 /init/finalized
 /init/initstat
 /init/library_version
-/init/session
-/init/session_mult_init
-/init/session_psets
-/init/session_self
 /init/timeout
 /init/version
 /io/async
@@ -1528,6 +1524,15 @@
 /rma/wintest
 /rma/wintest_shm
 /rma/win_zero
+/session/session
+/session/session_mult_init
+/session/session_re_init
+/session/session_psets
+/session/session_self
+/session/session_inter
+/session/session_4x4
+/session/session_bsend
+/session/session_local_only
 /spawn/concurrent_spawns
 /spawn/disconnect
 /spawn/disconnect2

test/mpi/session/Makefile.am

@@ -18,7 +18,8 @@ noinst_PROGRAMS = \
     session_self \
     session_inter \
     session_4x4 \
-    session_bsend
+    session_bsend \
+    session_local_only
 
 session_mult_init_SOURCES = session.c
 session_mult_init_CPPFLAGS = -DMULT_INIT $(AM_CPPFLAGS)

test/mpi/session/session_local_only.c

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) by Argonne National Laboratory
+ *     See COPYRIGHT in top-level directory
+ */
+
+#include "mpi.h"
+#include "stdio.h"
+
+/*
+static char MTEST_Descrip[] = "Test MPI Sessions local-only behavior.
+No communication is performed. Intended to run with a minimum of 2 MPI
+processes and at least 1 non-MPI process. This verifies the local,
+non-collective nature of MPI Sessions initialization and group
+construction APIs. Example launch command:
+
+  mpiexec -n 2 ./session_local_only : -n 1 true
+
+The world group size will be 3, but only 2 processes will initialize
+and make MPI calls. A correct implementation should not hang.
+*/
+
+int main(int argc, char *argv[])
+{
+    MPI_Session session;
+    MPI_Group group;
+    int rank, size;
+
+    MPI_Session_init(MPI_INFO_NULL, MPI_ERRORS_RETURN, &session);
+
+    MPI_Group_from_session_pset(session, "mpi://world", &group);
+    MPI_Group_rank(group, &rank);
+    MPI_Group_size(group, &size);
+    if (size < 3) {
+        /* no communicator so directly call errhandler */
+        MPI_Session_call_errhandler(session, 1);
+    }
+
+    MPI_Group_free(&group);
+    MPI_Session_finalize(&session);
+    if (rank == 0) {
+        printf("No Errors\n");
+    }
+
+    return 0;
+}

test/mpi/session/testlist

@@ -7,3 +7,5 @@ session_self 1
 session_inter 5
 session_4x4 16
 session_bsend 2
+# args to session_local_only append ": -n 1 true" to mpiexec
+session_local_only 2 timeLimit=10 arg=: arg=-n arg=1 arg=true