coll/base: neg. priority cleanup, verbose output improvements

* Print a verbose message if the component was disqualified because of
   a negative priority.
 * If a disqualified component provided a module, release it.
 * Display list of selected components in priority order
   - During the process of volunteering collective functions for a
     communicator, print the component name and priority. This will
     cause the verbose messages to be displayed in reverse priority
     order (lowest priority first, up to highest). This is helpful
     when determining which collective components are active in which
     order for a given communicator.
     To see the messages you need the following MCA parameter set to 9
     or higher: `-mca coll_base_verbose 9`
 * Adjust verbose for commonly needed verbose output from 10 to 9 to
   make it easier to access this information.

ompi/mca/coll/base/coll_base_comm_select.c

@@ -19,6 +19,7 @@
  *                         reserved.
  * Copyright (c) 2014      Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
+ * Copyright (c) 2016      IBM Corporation.  All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -52,6 +53,7 @@ struct avail_coll_t {
 
     int ac_priority;
     mca_coll_base_module_2_1_0_t *ac_module;
+    const char * ac_component_name;
 };
 typedef struct avail_coll_t avail_coll_t;
 
@@ -110,7 +112,7 @@ int mca_coll_base_comm_select(ompi_communicator_t * comm)
     int ret;
 
     /* Announce */
-    opal_output_verbose(10, ompi_coll_base_framework.framework_output,
+    opal_output_verbose(9, ompi_coll_base_framework.framework_output,
                         "coll:base:comm_select: new communicator: %s (cid %d)",
                         comm->c_name, comm->c_contextid);
 
@@ -143,6 +145,12 @@ int mca_coll_base_comm_select(ompi_communicator_t * comm)
 
         /* initialize the module */
         ret = avail->ac_module->coll_module_enable(avail->ac_module, comm);
+
+        opal_output_verbose(9, ompi_coll_base_framework.framework_output,
+                            "coll:base:comm_select: selecting  %10s, priority %3d, %s",
+                            avail->ac_component_name, avail->ac_priority,
+                            (OMPI_SUCCESS == ret ? "Enabled": "Disabled") );
+
         if (OMPI_SUCCESS == ret) {
 
             /* copy over any of the pointers */
@@ -295,9 +303,23 @@ static opal_list_t *check_components(opal_list_t * components,
             avail = OBJ_NEW(avail_coll_t);
             avail->ac_priority = priority;
             avail->ac_module = module;
+            // Point to the string so we don't have to free later
+            avail->ac_component_name = component->mca_component_name;
 
             opal_list_append(selectable, &avail->super);
         }
+        else {
+            opal_output_verbose(10, ompi_coll_base_framework.framework_output,
+                                "coll:base:comm_select: component disqualified: %s (priority %d < 0)",
+                                component->mca_component_name, priority );
+
+            // If the disqualified collective returned a module make sure we
+            // release it here, since it will become a leak otherwise.
+            if( NULL != module ) {
+                OBJ_RELEASE(module);
+                module = NULL;
+            }
+        }
     }
 
     /* If we didn't find any available components, return an error */