Re: [OMPI devel] malloc(0) warnings in post/wait and start/complete calls with GROUP_EMPTY

[Gilles Gouaillardet]

Lisandro,

here is attached a patch (master does things differently, so this has to 
be a one-off patch anyway)
could you please give it a try ?
btw, how do you get these warnings automatically ?

Cheers,

Gilles

On 2/2/2016 12:02 AM, Lisandro Dalcin wrote:
You might argue that the attached tests are naive, but still... (Open
MPI v1.10.2)

$ mpicc win_post_wait.c
$ mpiexec -n 1 ./a.out
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)
$ mpiexec -n 2 ./a.out
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)

$ mpicc win_start_complete.c
$ mpiexec -n 1 ./a.out
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)
$ mpiexec -n 2 ./a.out
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 76)
malloc debug: Request for 0 bytes (osc_pt2pt_active_target.c, 78)




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diff --git a/ompi/mca/osc/pt2pt/osc_pt2pt_active_target.c 
b/ompi/mca/osc/pt2pt/osc_pt2pt_active_target.c
index 1164413..03a6edc 100644
--- a/ompi/mca/osc/pt2pt/osc_pt2pt_active_target.c
+++ b/ompi/mca/osc/pt2pt/osc_pt2pt_active_target.c
@@ -12,7 +12,7 @@
  *                         reserved.
  * Copyright (c) 2010      IBM Corporation.  All rights reserved.
  * Copyright (c) 2012-2013 Sandia National Laboratories.  All rights reserved.
- * Copyright (c) 2015      Research Organization for Information Science
+ * Copyright (c) 2015-2016 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * $COPYRIGHT$
  *
@@ -213,15 +213,17 @@ ompi_osc_pt2pt_start(ompi_group_t *group,
                          "ompi_osc_pt2pt_start entering with group size %d...",
                          group_size));

-    ranks = get_comm_ranks(module, module->sc_group);
-    if (NULL == ranks) return OMPI_ERR_TEMP_OUT_OF_RESOURCE;
+    if (OPAL_LIKELY(0 < group_size)) {
+        ranks = get_comm_ranks(module, module->sc_group);
+        if (NULL == ranks) return OMPI_ERR_TEMP_OUT_OF_RESOURCE;

-    for (int i = 0 ; i < group_size ; ++i) {
-        /* when the post comes in we will be in an access epoch with this proc 
*/
-        module->peers[ranks[i]].access_epoch = true;
+        for (int i = 0 ; i < group_size ; ++i) {
+            /* when the post comes in we will be in an access epoch with this 
proc */
+            module->peers[ranks[i]].access_epoch = true;
+        }
+        free (ranks);
     }

-    free (ranks);

     OPAL_LIST_FOREACH_SAFE(pending_post, next, &module->pending_posts, 
ompi_osc_pt2pt_pending_post_t) {
         ompi_proc_t *pending_proc = ompi_comm_peer_lookup (module->comm, 
pending_post->rank);
@@ -284,8 +286,10 @@ ompi_osc_pt2pt_complete(ompi_win_t *win)
         return OMPI_ERR_RMA_SYNC;
     }

-    ranks = get_comm_ranks(module, module->sc_group);
-    if (NULL == ranks) return OMPI_ERR_TEMP_OUT_OF_RESOURCE;
+    if (OPAL_LIKELY(0 < ompi_group_size(module->sc_group))) {
+        ranks = get_comm_ranks(module, module->sc_group);
+        if (NULL == ranks) return OMPI_ERR_TEMP_OUT_OF_RESOURCE;
+    }

     OPAL_THREAD_LOCK(&module->lock);

@@ -375,9 +379,7 @@ ompi_osc_pt2pt_complete(ompi_win_t *win)

     OPAL_OUTPUT_VERBOSE((50, ompi_osc_base_framework.framework_output,
                          "ompi_osc_pt2pt_complete complete"));
-    free (ranks);
-
-    return OMPI_SUCCESS;
+    ret = OMPI_SUCCESS;

  cleanup:
     if (NULL != ranks) free(ranks);
@@ -428,6 +430,10 @@ ompi_osc_pt2pt_post(ompi_group_t *group,
     OPAL_OUTPUT_VERBOSE((50, ompi_osc_base_framework.framework_output,
                          "sending post messages"));

+    if (OPAL_UNLIKELY(0 == ompi_group_size(module->pw_group))) {
+        return OMPI_SUCCESS;
+    }
+
     ranks = get_comm_ranks(module, module->pw_group);
     if (NULL == ranks) {
         return OMPI_ERR_OUT_OF_RESOURCE;