Fix the vprotocol initialization.

Add a comment about the stages in the vprotocols initialization and why
we cant use the threading provided during the PML initialization.
Instead, use the OMPI internal threading status to prevent the use of
message logging in multi-threaded applications.

Signed-off-by: George Bosilca <bosilca@icl.utk.edu>

Author: bosilca

ompi/mca/pml/v/pml_v_component.c

@@ -28,6 +28,7 @@
 #include "ompi/mca/vprotocol/base/base.h"
 #include "pml_v_output.h"
 #include "pml_v.h"
+#include "ompi/runtime/mpiruntime.h"
 
 static int mca_pml_v_component_register(void);
 static int mca_pml_v_component_open(void);
@@ -61,9 +62,6 @@ mca_pml_base_component_2_0_0_t mca_pml_v_component =
     .pmlm_finalize = mca_pml_v_component_finalize,
 };
 
-static bool pml_v_enable_progress_treads = OPAL_ENABLE_PROGRESS_THREADS;
-static bool pml_v_enable_mpi_thread_multiple = 1;
-
 static char *ompi_pml_vprotocol_include_list;
 static char *ompi_pml_v_output;
 static int ompi_pml_v_verbose;
@@ -205,17 +203,19 @@ static int mca_pml_v_component_parasite_close(void)
 
 
 /*******************************************************************************
- * Init/finalize for MCA PML components
+ * The init function for the V PML is never supposed to be called, as the mechanism
+ * that enables the PML V to work require a real PML to move data across. Thus, a
+ * normal PML should be selected (so the PML V cannot be in the MCA list of PMLs)
+ * and if the PML V is enabled (via the activation of a vprotocol) it will insert
+ * itself before the selected PML (assuming no DIRECT_call PML).
  */
-static mca_pml_base_module_t *mca_pml_v_component_init(int *priority,
-                                                      bool enable_progress_threads,
-                                                      bool enable_mpi_thread_multiple)
+static mca_pml_base_module_t*
+mca_pml_v_component_init(int *priority,
+                         bool enable_progress_threads,
+                         bool enable_mpi_thread_multiple)
 {
     V_OUTPUT_VERBOSE(1, "init: I'm not supposed to be here until BTL loading stuff gets fixed!? That's strange...");
 
-    pml_v_enable_progress_treads = enable_progress_threads;
-    pml_v_enable_mpi_thread_multiple = enable_mpi_thread_multiple;
-
     /* I NEVER want to be the selected PML, so I report less than possible
      * priority and a NULL module
      */
@@ -249,8 +249,8 @@ static int mca_pml_v_enable(bool enable)
     if(enable) {
         /* Check if a protocol have been selected during init */
         if(! mca_vprotocol_base_selected())
-            mca_vprotocol_base_select(pml_v_enable_progress_treads,
-                                      pml_v_enable_mpi_thread_multiple);
+            mca_vprotocol_base_select(OPAL_ENABLE_PROGRESS_THREADS,
+                                      ompi_mpi_thread_multiple);
 
         /* Check if we succeeded selecting a protocol */
         if(mca_vprotocol_base_selected()) {

ompi/mca/vprotocol/pessimist/vprotocol_pessimist_component.c

@@ -100,7 +100,7 @@ static int mca_vprotocol_pessimist_component_register(void)
 static int mca_vprotocol_pessimist_component_open(void)
 {
     V_OUTPUT_VERBOSE(500, "vprotocol_pessimist: component_open: read priority %d", _priority);
-  return OMPI_SUCCESS;
+    return OMPI_SUCCESS;
 }
 
 static int mca_vprotocol_pessimist_component_close(void)
@@ -111,16 +111,22 @@ static int mca_vprotocol_pessimist_component_close(void)
 
 /** VPROTOCOL level functions (same as PML one)
   */
-static mca_vprotocol_base_module_t *mca_vprotocol_pessimist_component_init( int* priority,
-                                                                          bool enable_progress_threads,
-                                                                          bool enable_mpi_threads)
+static mca_vprotocol_base_module_t*
+mca_vprotocol_pessimist_component_init( int* priority,
+                                        bool enable_progress_threads,
+                                        bool enable_mpi_threads)
 {
     V_OUTPUT_VERBOSE(500, "vprotocol_pessimist: component_init");
     *priority = _priority;
 
     /* sanity check */
-    if(enable_mpi_threads)
-    {
+    if(enable_mpi_threads) {
+        /**
+         * Prevent the pessimistic protocol from activating if we are in a potentially multithreaded
+         * applications. The reason is that without tracking the thread initiator of messages it is
+         * extrmely difficult to provide a global message ordering in threaded-scenarios. Thus, the
+         * safe approach is to turn off the logger.
+         */
         opal_output(0, "vprotocol_pessimist: component_init: threads are enabled, and not supported by vprotocol pessimist fault tolerant layer, will not load");
         return NULL;
     }