From c4a146efc40c66de7d06a387465c9f7ea9b2e280 Mon Sep 17 00:00:00 2001
From: jhendersonHDF <jhenderson@hdfgroup.org>
Date: Thu, 19 Oct 2023 08:14:20 -0500
Subject: [PATCH] Fix issue with unmatched messages in ph5diff (#3719)

---
 release_docs/RELEASE.txt        | 13 +++++++++++++
 tools/lib/h5diff.c              |  3 ---
 tools/src/h5diff/ph5diff_main.c |  8 ++++----
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index ea774af456..83c20b07d3 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -791,6 +791,19 @@ Bug Fixes since HDF5-1.14.0 release
 
     Tools
     -----
+    - Fixed an issue with unmatched MPI messages in ph5diff
+
+      The "manager" MPI rank in ph5diff was unintentionally sending "program end"
+      messages to its workers twice, leading to an error from MPICH similar to the
+      following:
+
+      Abort(810645519) on node 1 (rank 1 in comm 0): Fatal error in internal_Finalize: Other MPI error, error stack:
+      internal_Finalize(50)...........: MPI_Finalize failed
+      MPII_Finalize(394)..............:
+      MPIR_Comm_delete_internal(1224).: Communicator (handle=44000000) being freed has 1 unmatched message(s)
+      MPIR_Comm_release_always(1250)..:
+      MPIR_finalize_builtin_comms(154):
+
     - Fixed an issue in h5repack for variable-length typed datasets
 
       When repacking datasets into a new file, h5repack tries to determine whether
diff --git a/tools/lib/h5diff.c b/tools/lib/h5diff.c
index 924f9f35de..15f2a1428b 100644
--- a/tools/lib/h5diff.c
+++ b/tools/lib/h5diff.c
@@ -1485,9 +1485,6 @@ diff_match(hid_t file1_id, const char *grp1, trav_info_t *info1, hid_t file2_id,
                 } /* end else */
             }     /* end while */
 
-            for (i = 1; (int)i < g_nTasks; i++)
-                MPI_Send(NULL, 0, MPI_BYTE, (int)i, MPI_TAG_END, MPI_COMM_WORLD);
-
             /* Print any final data waiting in our queue */
             print_incoming_data();
         } /* end if */
diff --git a/tools/src/h5diff/ph5diff_main.c b/tools/src/h5diff/ph5diff_main.c
index 0f43261078..f90bd484ac 100644
--- a/tools/src/h5diff/ph5diff_main.c
+++ b/tools/src/h5diff/ph5diff_main.c
@@ -127,7 +127,7 @@ ph5diff_worker(int nID)
             char filenames[2][MAX_FILENAME];
 
             /* Retrieve filenames */
-            MPI_Recv(filenames, MAX_FILENAME * 2, MPI_CHAR, 0, MPI_ANY_TAG, MPI_COMM_WORLD, &Status);
+            MPI_Recv(filenames, MAX_FILENAME * 2, MPI_CHAR, 0, MPI_TAG_PARALLEL, MPI_COMM_WORLD, &Status);
 
             /* disable error reporting */
             H5E_BEGIN_TRY
@@ -173,7 +173,7 @@ ph5diff_worker(int nID)
 
                 /* When get token, send all of our output to the manager task and then return the token */
                 for (i = 0; i < outBuffOffset; i += PRINT_DATA_MAX_SIZE)
-                    MPI_Send(outBuff + i, PRINT_DATA_MAX_SIZE, MPI_BYTE, 0, MPI_TAG_PRINT_DATA,
+                    MPI_Send(outBuff + i, PRINT_DATA_MAX_SIZE, MPI_CHAR, 0, MPI_TAG_PRINT_DATA,
                              MPI_COMM_WORLD);
 
                 /* An overflow file exists, so we send it's output to the manager too and then delete it */
@@ -188,7 +188,7 @@ ph5diff_worker(int nID)
                     while ((tmp = getc(overflow_file)) >= 0) {
                         *(out_data + i++) = (char)tmp;
                         if (i == PRINT_DATA_MAX_SIZE) {
-                            MPI_Send(out_data, PRINT_DATA_MAX_SIZE, MPI_BYTE, 0, MPI_TAG_PRINT_DATA,
+                            MPI_Send(out_data, PRINT_DATA_MAX_SIZE, MPI_CHAR, 0, MPI_TAG_PRINT_DATA,
                                      MPI_COMM_WORLD);
                             i = 0;
                             memset(out_data, 0, PRINT_DATA_MAX_SIZE);
@@ -196,7 +196,7 @@ ph5diff_worker(int nID)
                     }
 
                     if (i > 0)
-                        MPI_Send(out_data, PRINT_DATA_MAX_SIZE, MPI_BYTE, 0, MPI_TAG_PRINT_DATA,
+                        MPI_Send(out_data, PRINT_DATA_MAX_SIZE, MPI_CHAR, 0, MPI_TAG_PRINT_DATA,
                                  MPI_COMM_WORLD);
 
                     fclose(overflow_file);