Make the opening of the io framework be lazy -- only occurs at the

first invocation of MPI_File_open or MPI_File_delete (whichever is
first).  The io framework is then only closed down if it was
successfully opened.  

This is the first [atomic] step to having a progress thread in the
ROMIO component; it wasn't strictly *necessary*, but it's logically
the same direction and provided a good test case.

This commit was SVN r3895.

src/mca/base/mca_base_init_select_components.c

@@ -87,12 +87,8 @@ int mca_base_init_select_components(int requested,
   allow_multi_user_threads &= user_threads;
   have_hidden_threads |= hidden_threads;
 
-  if (OMPI_SUCCESS != mca_io_base_find_available(&user_threads, 
-                                                 &hidden_threads)) {
-    return OMPI_ERROR;
-  }
-  allow_multi_user_threads &= user_threads;
-  have_hidden_threads |= hidden_threads;
+  /* io components are selected later, because the io framework is
+     opened lazily (at the first MPI_File_* function invocation). */
 
   /* Now that we have a final list of all available modules, do the
      selection.  pml is already selected. */

src/mpi/c/file_delete.c

@@ -20,6 +20,7 @@
 #include "errhandler/errhandler.h"
 #include "info/info.h"
 #include "file/file.h"
+#include "mca/io/io.h"
 #include "mca/io/base/base.h"
 
 #if OMPI_HAVE_WEAK_SYMBOLS && OMPI_PROFILING_DEFINES
@@ -48,6 +49,38 @@ int MPI_File_delete(char *filename, MPI_Info info)
         OMPI_ERRHANDLER_CHECK(rc, MPI_FILE_NULL, rc, FUNC_NAME);
     }
 
+    /* Note that MPI-2:9.7 (p265) says that errors in MPI_FILE_OPEN
+       (before the file handle is created) should invoke the default
+       error handler on MPI_FILE_NULL.  Hence, if we get a file handle
+       out of ompi_file_open(), invoke the error handler on that.  If
+       not, invoke the error handler on MPI_FILE_NULL. */
+
+    /* The io framework is only initialized lazily.  If it hasn't
+       already been initialized, do so now (note that MPI_FILE_OPEN
+       and MPI_FILE_DELETE are the only two places that it will be
+       initialized). */
+
+    if (!(mca_io_base_components_opened_valid ||
+          mca_io_base_components_available_valid)) {
+        bool user_threads = true;
+        bool hidden_threads = true;
+        if (OMPI_SUCCESS != (rc = mca_io_base_open())) {
+            return OMPI_ERRHANDLER_INVOKE(MPI_FILE_NULL, rc, FUNC_NAME);
+        }
+        /* JMS Need to do something here with user_threads and
+           hidden_threads -- technically this is no longer a query,
+           it's a mandate.  The query part is left over from when this
+           function was invoked during MPI_INIT.  Since we've now
+           long-since decided the user threads and hidden threads
+           stuff (i.e., during MPI_INIT), we can't change them now.
+           This is not hugely important now, since ROMIO is the only
+           io component that we have, but it should be fixed. */
+        if (OMPI_SUCCESS != (rc = mca_io_base_find_available(&user_threads, 
+                                                             &hidden_threads))) {
+            return OMPI_ERRHANDLER_INVOKE(MPI_FILE_NULL, rc, FUNC_NAME);
+        }
+    }
+
     /* Since there is no MPI_File handle associated with this
        function, the MCA has to do a selection and perform the
        action */

src/mpi/c/file_open.c

@@ -20,6 +20,8 @@
 #include "errhandler/errhandler.h"
 #include "info/info.h"
 #include "file/file.h"
+#include "mca/io/io.h"
+#include "mca/io/base/base.h"
 
 #if OMPI_HAVE_WEAK_SYMBOLS && OMPI_PROFILING_DEFINES
 #pragma weak MPI_File_open = PMPI_File_open
@@ -54,6 +56,32 @@ int MPI_File_open(MPI_Comm comm, char *filename, int amode,
        out of ompi_file_open(), invoke the error handler on that.  If
        not, invoke the error handler on MPI_FILE_NULL. */
 
+    /* The io framework is only initialized lazily.  If it hasn't
+       already been initialized, do so now (note that MPI_FILE_OPEN
+       and MPI_FILE_DELETE are the only two places that it will be
+       initialized). */
+
+    if (!(mca_io_base_components_opened_valid ||
+          mca_io_base_components_available_valid)) {
+        bool user_threads = true;
+        bool hidden_threads = true;
+        if (OMPI_SUCCESS != (rc = mca_io_base_open())) {
+            return OMPI_ERRHANDLER_INVOKE(MPI_FILE_NULL, rc, FUNC_NAME);
+        }
+        /* JMS Need to do something here with user_threads and
+           hidden_threads -- technically this is no longer a query,
+           it's a mandate.  The query part is left over from when this
+           function was invoked during MPI_INIT.  Since we've now
+           long-since decided the user threads and hidden threads
+           stuff (i.e., during MPI_INIT), we can't change them now.
+           This is not hugely important now, since ROMIO is the only
+           io component that we have, but it should be fixed. */
+        if (OMPI_SUCCESS != (rc = mca_io_base_find_available(&user_threads, 
+                                                             &hidden_threads))) {
+            return OMPI_ERRHANDLER_INVOKE(MPI_FILE_NULL, rc, FUNC_NAME);
+        }
+    }
+
     /* Create an empty MPI_File handle */
 
     *fh = MPI_FILE_NULL;

src/mpi/runtime/ompi_mpi_finalize.c

@@ -184,8 +184,14 @@ int ompi_mpi_finalize(void)
 
     /* Close down MCA modules */
 
-    if (OMPI_SUCCESS != (ret = mca_io_base_close())) {
-	return ret;
+    /* io is opened lazily, so it's only necessary to close it if it
+       was actually opened */
+
+    if (mca_io_base_components_opened_valid ||
+        mca_io_base_components_available_valid) {
+        if (OMPI_SUCCESS != (ret = mca_io_base_close())) {
+            return ret;
+        }
     }
     if (OMPI_SUCCESS != (ret = mca_topo_base_close())) {
 	return ret;

src/mpi/runtime/ompi_mpi_init.c

@@ -157,10 +157,9 @@ int ompi_mpi_init(int argc, char **argv, int requested, int *provided)
         error = "mca_topo_base_open() failed";
         goto error;
     }
-    if (OMPI_SUCCESS != (ret = mca_io_base_open())) {
-        error = "mca_io_base_open() failed";
-        goto error;
-    }
+
+    /* The io framework is initialized lazily, at the first use of any
+       MPI_File_* function, so it is not included here. */
 
     /* initialize module exchange */
     if (OMPI_SUCCESS != (ret = mca_base_modex_init())) {