Merge pull request #7525 from rhc54/topic/fence

Correct fence logic in MPI_Init

ompi/runtime/ompi_mpi_init.c

@@ -679,18 +679,15 @@ int ompi_mpi_init(int argc, char **argv, int requested, int *provided,
 #endif
 
     if (!ompi_singleton) {
-        /* If we have a non-blocking fence:
-         * if we are doing an async modex, but we are collecting all
+        if (opal_pmix_base_async_modex) {
+            /* if we are doing an async modex, but we are collecting all
              * data, then execute the non-blocking modex in the background.
              * All calls to modex_recv will be cached until the background
              * modex completes. If collect_all_data is false, then we skip
              * the fence completely and retrieve data on-demand from the
              * source node.
-         *
-         * If we do not have a non-blocking fence, then we must always
-         * execute the blocking fence as the system does not support
-         * later data retrieval. */
-        if (opal_pmix_base_async_modex) {
+             */
+            if (opal_pmix_collect_all_data) {
                 /* execute the fence_nb in the background to collect
                  * the data */
                 background_fence = true;
@@ -704,13 +701,17 @@ int ompi_mpi_init(int argc, char **argv, int requested, int *provided,
                     error = "PMIx_Fence_nb() failed";
                     goto error;
                 }
-
-        } else if (!opal_pmix_base_async_modex) {
-            /* we want to do the modex */
+            }
+        } else {
+            /* we want to do the modex - we block at this point, but we must
+             * do so in a manner that allows us to call opal_progress so our
+             * event library can be cycled as we have tied PMIx to that
+             * event base */
             active = true;
             OPAL_POST_OBJECT(&active);
             PMIX_INFO_LOAD(&info[0], PMIX_COLLECT_DATA, &opal_pmix_collect_all_data, PMIX_BOOL);
-            if( PMIX_SUCCESS != (rc = PMIx_Fence_nb(NULL, 0, info, 1, fence_release, (void*)&active))) {
+            rc = PMIx_Fence_nb(NULL, 0, info, 1, fence_release, (void*)&active);
+            if( PMIX_SUCCESS != rc) {
                 ret = opal_pmix_convert_status(rc);
                 error = "PMIx_Fence() failed";
                 goto error;