[svn-r5689] Purpose:

    Bug Fix

Description:
    When parallel I/O is used, the MPI-I/O VFL driver uses a "lazy" model to
    call MPI_File_set_view() in order to reduce the number of calls to this
    function.  However, this is unsafe, because if a collective I/O which uses
    MPI derived types (and thus uses MPI_File_set_view()) is immediately
    followed by an independent I/O, the code will attempt to call
    MPI_File_set_view() in order to switch back to the default view of the
    file.  MPI_File_set_view() is a collective call however, and this causes
    the application to hang.

Solution:
    Removed "lazy" MPI_File_set_view() code, instead set the file view when it
    is needed (with MPI derived types) and immediately set the file view back to
    the default view before leaving the I/O routine.

Platforms tested:
    IRIX64 6.5 (modi4) w/parallel.  Also, tested with the latest development
    and release code for the SAF library, which now works correctly with this
    change.  (Although the release branch of the SAF library seems to have a
    bug, this 1.4.4 release candidate code gets as far as the version the SAF
    library is released on top of (1.4.2-patch1, I believe)).

2 files changed, 39 insertions, 21 deletions

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index cfed11b..b24171c 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -71,6 +71,9 @@ New Features
 
   o Parallel Library
   ==================
+    * Fixed bug in parallel I/O routines where a collective I/O which used
+      MPI derived types, followed by an independent I/O would cause the library
+      to hang.  QAK 2002/06/24
     * Added environment variable flag to control whether creating MPI derived
       typed is preferred or not.  This can affect performance, depending on
       which way the MPI-I/O library is optimized for.  The default is set to
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index 6724d18..09372f2 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -70,7 +70,6 @@ typedef struct H5FD_mpio_t {
     haddr_t	eof;		/*end-of-file marker			*/
     haddr_t	eoa;		/*end-of-address marker			*/
     haddr_t	last_eoa;	/* Last known end-of-address marker	*/
-    unsigned	old_use_view;   /*remember value of use_view		*/
 } H5FD_mpio_t;
 
 /* Prototypes */
@@ -1179,6 +1178,11 @@ H5FD_mpio_get_eof(H5FD_t *_file)
  *              the address of the dataset in MPI_File_set_view() calls, as
  *              necessary.
  *
+ *              Quincey Koziol - 2002/06/24
+ *              Removed "lazy" MPI_File_set_view() calls, since they would fail
+ *              if the first I/O was a collective I/O using MPI derived types
+ *              and the next I/O was an independent I/O.
+ *
  *-------------------------------------------------------------------------
  */
 static herr_t
@@ -1193,7 +1197,7 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t UNUSED type, hid_t dxpl_id, haddr_t add
     MPI_Status  		mpi_stat;
     MPI_Datatype		buf_type, file_type;
     int         		size_i, bytes_read, n;
-    unsigned			use_view_this_time=0, used_view_last_time;
+    unsigned			use_view_this_time=0;
     herr_t              	ret_value=SUCCEED;
 
     FUNC_ENTER(H5FD_mpio_read, FAIL);
@@ -1266,20 +1270,14 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t UNUSED type, hid_t dxpl_id, haddr_t add
     }
 
     /*
-     * Don't bother to reset the view if we're not using the types this time,
-     * and did we didn't use them last time either.
+     * Set the file view when we are using MPI derived types
      */
-    used_view_last_time = file->old_use_view;
-    if (used_view_last_time || /* change to new ftype or MPI_BYTE */
-            use_view_this_time) { 	/* almost certainly a different ftype */
+    if (use_view_this_time) {
         /*OKAY: CAST DISCARDS CONST QUALIFIER*/
         if (MPI_SUCCESS != MPI_File_set_view(file->f, mpi_disp, MPI_BYTE, file_type, (char*)"native",  file->info))
             HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_File_set_view failed");
-    }
+    } /* end if */
     
-    /* Keep the 'use view' flag around for the next I/O */
-    file->old_use_view = use_view_this_time;
-
     /* Read the data. */
     assert(H5FD_MPIO_INDEPENDENT==dx->xfer_mode || H5FD_MPIO_COLLECTIVE==dx->xfer_mode);
     if (H5FD_MPIO_INDEPENDENT==dx->xfer_mode) {
@@ -1335,6 +1333,15 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t UNUSED type, hid_t dxpl_id, haddr_t add
         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file read failed");
 
     /*
+     * Reset the file view when we used MPI derived types
+     */
+    if (use_view_this_time) {
+        /*OKAY: CAST DISCARDS CONST QUALIFIER*/
+        if (MPI_SUCCESS != MPI_File_set_view(file->f, 0, MPI_BYTE, MPI_BYTE, (char*)"native",  file->info))
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_File_set_view failed");
+    } /* end if */
+    
+    /*
      * This gives us zeroes beyond end of physical MPI file.  What about
      * reading past logical end of HDF5 file???
      */
@@ -1469,6 +1476,11 @@ done:
  *              the address of the dataset in MPI_File_set_view() calls, as
  *              necessary.
  *
+ *              Quincey Koziol - 2002/06/24
+ *              Removed "lazy" MPI_File_set_view() calls, since they would fail
+ *              if the first I/O was a collective I/O using MPI derived types
+ *              and the next I/O was an independent I/O.
+ *
  *-------------------------------------------------------------------------
  */
 static herr_t
@@ -1483,7 +1495,7 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr,
     MPI_Status			mpi_stat;
     MPI_Datatype		buf_type, file_type;
     int         		size_i, bytes_written;
-    unsigned			use_view_this_time=0, used_view_last_time;
+    unsigned			use_view_this_time=0;
     herr_t              	ret_value=SUCCEED;
 
     FUNC_ENTER(H5FD_mpio_write, FAIL);
@@ -1556,20 +1568,14 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr,
     }
 
     /*
-     * Don't bother to reset the view if we're not using the types this time,
-     * and did we didn't use them last time either.
+     * Set the file view when we are using MPI derived types
      */
-    used_view_last_time = file->old_use_view;
-    if (used_view_last_time ||	/* change to new ftype or MPI_BYTE */
-            use_view_this_time) {	/* almost certainly a different ftype */
+    if (use_view_this_time) {
         /*OKAY: CAST DISCARDS CONST QUALIFIER*/
         if (MPI_SUCCESS != MPI_File_set_view(file->f, mpi_disp, MPI_BYTE, file_type, (char*)"native", file->info))
             HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_File_set_view failed");
-    }
+    } /* end if */
     
-    /* Keep the 'use view' flag around for the next I/O */
-    file->old_use_view = use_view_this_time;
-
     /* Only p<round> will do the actual write if all procs in comm write same data */
     if ((type!=H5FD_MEM_DRAW) && H5_mpi_1_metawrite_g) {
         if (file->mpi_rank != file->mpi_round) {
@@ -1641,6 +1647,15 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr,
     if (bytes_written<0 || bytes_written>size_i)
         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file write failed");
 
+    /*
+     * Reset the file view when we used MPI derived types
+     */
+    if (use_view_this_time) {
+        /*OKAY: CAST DISCARDS CONST QUALIFIER*/
+        if (MPI_SUCCESS != MPI_File_set_view(file->f, 0, MPI_BYTE, MPI_BYTE, (char*)"native",  file->info))
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_File_set_view failed");
+    } /* end if */
+    
     /* Forget the EOF value (see H5FD_mpio_get_eof()) --rpm 1999-08-06 */
     file->eof = HADDR_UNDEF;