diff --git a/.github/workflows/abi-report.yml b/.github/workflows/abi-report.yml
index 9abbd2fd54c..5faa1f297b2 100644
--- a/.github/workflows/abi-report.yml
+++ b/.github/workflows/abi-report.yml
@@ -49,7 +49,7 @@ jobs:
       - uses: actions/checkout@v4.1.7
 
       - name: Get published binary (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
             name: tgz-ubuntu-2204_gcc-binary
             path: ${{ github.workspace }}
diff --git a/.github/workflows/clang-format-check.yml b/.github/workflows/clang-format-check.yml
index f0d89558baa..c4d68a8f004 100644
--- a/.github/workflows/clang-format-check.yml
+++ b/.github/workflows/clang-format-check.yml
@@ -11,7 +11,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4.1.7
     - name: Run clang-format style check for C and Java code
-      uses: DoozyX/clang-format-lint-action@v0.13
+      uses: DoozyX/clang-format-lint-action@v0.17
       with:
         source: '.'
         extensions: 'c,h,cpp,hpp,java'
diff --git a/.github/workflows/clang-format-fix.yml b/.github/workflows/clang-format-fix.yml
index 882e0b64a9f..2ce9f6e9dad 100644
--- a/.github/workflows/clang-format-fix.yml
+++ b/.github/workflows/clang-format-fix.yml
@@ -23,7 +23,7 @@ jobs:
     steps:
     - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
     - name: Fix C and Java formatting issues detected by clang-format
-      uses: DoozyX/clang-format-lint-action@9ea72631b74e61ce337d0839a90e76180e997283 # v0.13
+      uses: DoozyX/clang-format-lint-action@d3c7f85989e3b6416265a0d12f8b4a8aa8b0c4ff # v0.13
       with:
         source: '.'
         extensions: 'c,h,cpp,hpp,java'
diff --git a/.github/workflows/cmake-bintest.yml b/.github/workflows/cmake-bintest.yml
index bbe0172acbf..104818920b5 100644
--- a/.github/workflows/cmake-bintest.yml
+++ b/.github/workflows/cmake-bintest.yml
@@ -33,7 +33,7 @@ jobs:
 
       # Get files created by cmake-ctest script
       - name: Get published binary (Windows)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: zip-vs2022_cl-${{ inputs.build_mode }}-binary
               path: ${{ github.workspace }}/hdf5
@@ -107,7 +107,7 @@ jobs:
           distribution: 'temurin'
 
       - name: Get published binary (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-ubuntu-2204_gcc-${{ inputs.build_mode }}-binary
               path: ${{ github.workspace }}
@@ -147,7 +147,7 @@ jobs:
   # MacOS w/ Clang + CMake
   #
     name: "MacOS Clang Binary Test"
-    runs-on: macos-latest
+    runs-on: macos-13
     steps:
       - name: Install Dependencies (MacOS)
         run: brew install ninja doxygen
@@ -159,9 +159,9 @@ jobs:
           distribution: 'temurin'
 
       - name: Get published binary (MacOS)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
-              name: tgz-osx-${{ inputs.build_mode }}-binary
+              name: tgz-osx13-${{ inputs.build_mode }}-binary
               path: ${{ github.workspace }}
 
       - name: Uncompress hdf5 binary (MacOS)
@@ -204,3 +204,64 @@ jobs:
           cmake --workflow --preset=ci-StdShar-OSX-Clang --fresh
         shell: bash
 
+  test_binary_mac_latest:
+  # MacOS w/ Clang + CMake
+  #
+    name: "MacOS Clang Binary Test"
+    runs-on: macos-latest
+    steps:
+      - name: Install Dependencies (MacOS_latest)
+        run: brew install ninja doxygen
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Get published binary (MacOS_latest)
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
+        with:
+          name: tgz-osx-${{ inputs.build_mode }}-binary
+          path: ${{ github.workspace }}
+
+      - name: Uncompress hdf5 binary (MacOS_latest)
+        run:  |
+          cd "${{ github.workspace }}"
+          tar -zxvf ${{ github.workspace }}/HDF5-*-Darwin.tar.gz --strip-components 1
+
+      - name: set hdf5lib name
+        id: set-hdf5lib-name
+        run: |
+          HDF5DIR=${{ github.workspace }}/HDF_Group/HDF5/
+          FILE_NAME_HDF5=$(ls ${{ github.workspace }}/HDF_Group/HDF5)
+          echo "HDF5_ROOT=$HDF5DIR$FILE_NAME_HDF5" >> $GITHUB_OUTPUT
+          echo "HDF5_PLUGIN_PATH=$HDF5_ROOT/lib/plugin" >> $GITHUB_OUTPUT
+
+      - name: List files for the binaries (MacOS_latest)
+        run: |
+          ls -l ${{ github.workspace }}/HDF_Group/HDF5
+
+      - name: List files for the space (MacOS_latest)
+        run: |
+          ls ${{ github.workspace }}
+          ls ${{ runner.workspace }}
+
+      # symlinks the compiler executables to a common location 
+      - name: Setup GNU Fortran
+        uses: fortran-lang/setup-fortran@v1
+        id: setup-fortran
+        with:
+          compiler: gcc
+          version: 12
+
+      - name: Run ctest (MacOS_latest)
+        id: run-ctest
+        env:
+          HDF5_ROOT: ${{ steps.set-hdf5lib-name.outputs.HDF5_ROOT }}
+          HDF5_PLUGIN_PATH: ${{ steps.set-hdf5lib-name.outputs.HDF5_PLUGIN_PATH }}
+        run: |
+          cd "${{ steps.set-hdf5lib-name.outputs.HDF5_ROOT }}/share/HDF5Examples"
+          cmake --workflow --preset=ci-StdShar-OSX-Clang --fresh
+        shell: bash
+
diff --git a/.github/workflows/cmake-ctest.yml b/.github/workflows/cmake-ctest.yml
index 70baea28baa..162519831d7 100644
--- a/.github/workflows/cmake-ctest.yml
+++ b/.github/workflows/cmake-ctest.yml
@@ -60,7 +60,7 @@ jobs:
 
       # Get files created by release script
       - name: Get zip-tarball (Windows)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: zip-tarball
               path: ${{ github.workspace }}
@@ -86,11 +86,15 @@ jobs:
           cmake --workflow --preset=${{ inputs.preset_name }}-MSVC --fresh
         shell: bash
 
-      - name: Publish binary (Windows)
-        id: publish-ctest-binary
+      - name: Create build folders (Windows)
         run: |
           mkdir "${{ runner.workspace }}/build"
           mkdir "${{ runner.workspace }}/build/hdf5"
+        shell: bash
+
+      - name: Publish binary (Windows)
+        id: publish-ctest-binary
+        run: |
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING_LBNL_HDF5 -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-MSVC/README.md -Destination ${{ runner.workspace }}/build/hdf5/
@@ -102,8 +106,6 @@ jobs:
       - name: Publish msi binary (Windows)
         id: publish-ctest-msi-binary
         run: |
-          mkdir "${{ runner.workspace }}/build"
-          mkdir "${{ runner.workspace }}/build/hdf5"
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING_LBNL_HDF5 -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-MSVC/README.md -Destination ${{ runner.workspace }}/build/hdf5/
@@ -164,7 +166,7 @@ jobs:
 
       # Get files created by release script
       - name: Get tgz-tarball (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-tarball
               path: ${{ github.workspace }}
@@ -273,6 +275,12 @@ jobs:
         with:
           version: "1.9.7"
 
+      - name: Set up JDK 19
+        uses: actions/setup-java@v4
+        with:
+          java-version: '19'
+          distribution: 'temurin'
+
       - name: Set file base name (MacOS)
         id: set-file-base
         run: |
@@ -288,7 +296,7 @@ jobs:
 
       # Get files created by release script
       - name: Get tgz-tarball (MacOS)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-tarball
               path: ${{ github.workspace }}
@@ -326,7 +334,7 @@ jobs:
           cp ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-Clang/README.md ${{ runner.workspace }}/build/hdf5
           cp ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-Clang/*.tar.gz ${{ runner.workspace }}/build/hdf5
           cd "${{ runner.workspace }}/build"
-          tar -zcvf ${{ steps.set-file-base.outputs.FILE_BASE }}-osx.tar.gz hdf5
+          tar -zcvf ${{ steps.set-file-base.outputs.FILE_BASE }}-osx13.tar.gz hdf5
         shell: bash
 
       - name: List files in the space (MacOS)
@@ -336,6 +344,95 @@ jobs:
 
       # Save files created by ctest script
       - name: Save published binary (MacOS)
+        uses: actions/upload-artifact@v4
+        with:
+              name: tgz-osx13-binary
+              path: ${{ runner.workspace }}/build/${{ steps.set-file-base.outputs.FILE_BASE }}-osx13.tar.gz
+              if-no-files-found: error # 'warn' or 'ignore' are also available, defaults to `warn`
+
+  build_and_test_mac_latest:
+  # MacOS w/ Clang + CMake
+  #
+    name: "MacOS Clang CMake"
+    runs-on: macos-latest
+    steps:
+      - name: Install Dependencies (MacOS_latest)
+        run: brew install ninja
+
+      - name: Install Dependencies
+        uses: ssciwr/doxygen-install@v1
+        with:
+          version: "1.9.7"
+
+      - name: Set up JDK 19
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Set file base name (MacOS_latest)
+        id: set-file-base
+        run: |
+          FILE_NAME_BASE=$(echo "${{ inputs.file_base }}")
+          echo "FILE_BASE=$FILE_NAME_BASE" >> $GITHUB_OUTPUT
+          if [[ '${{ inputs.use_environ }}' == 'release' ]]
+          then
+            SOURCE_NAME_BASE=$(echo "${{ inputs.snap_name }}")
+          else
+            SOURCE_NAME_BASE=$(echo "hdfsrc")
+          fi
+          echo "SOURCE_BASE=$SOURCE_NAME_BASE" >> $GITHUB_OUTPUT
+
+      # Get files created by release script
+      - name: Get tgz-tarball (MacOS_latest)
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
+        with:
+              name: tgz-tarball
+              path: ${{ github.workspace }}
+
+      - name: List files for the space (MacOS_latest)
+        run: |
+              ls ${{ github.workspace }}
+              ls ${{ runner.workspace }}
+
+      - name: Uncompress source (MacOS_latest)
+        run: tar -zxvf ${{ github.workspace }}/${{ steps.set-file-base.outputs.FILE_BASE }}.tar.gz
+
+      # symlinks the compiler executables to a common location 
+      - name: Setup GNU Fortran
+        uses: fortran-lang/setup-fortran@v1
+        id: setup-fortran
+        with:
+          compiler: gcc
+          version: 12
+
+      - name: Run ctest (MacOS_latest)
+        id: run-ctest
+        run: |
+          cd "${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}"
+          cmake --workflow --preset=${{ inputs.preset_name }}-OSX-Clang --fresh
+        shell: bash
+
+      - name: Publish binary (MacOS_latest)
+        id: publish-ctest-binary
+        run: |
+          mkdir "${{ runner.workspace }}/build"
+          mkdir "${{ runner.workspace }}/build/hdf5"
+          cp ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING ${{ runner.workspace }}/build/hdf5
+          cp ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING_LBNL_HDF5 ${{ runner.workspace }}/build/hdf5
+          cp ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-Clang/README.md ${{ runner.workspace }}/build/hdf5
+          cp ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-Clang/*.tar.gz ${{ runner.workspace }}/build/hdf5
+          cd "${{ runner.workspace }}/build"
+          tar -zcvf ${{ steps.set-file-base.outputs.FILE_BASE }}-osx.tar.gz hdf5
+        shell: bash
+
+      - name: List files in the space (MacOS_latest)
+        run: |
+              ls ${{ github.workspace }}
+              ls -l ${{ runner.workspace }}
+
+      # Save files created by ctest script
+      - name: Save published binary (MacOS_latest)
         uses: actions/upload-artifact@v4
         with:
               name: tgz-osx-binary
@@ -369,7 +466,7 @@ jobs:
 
       # Get files created by release script
       - name: Get tgz-tarball (Linux S3)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-tarball
               path: ${{ github.workspace }}
@@ -447,7 +544,7 @@ jobs:
 
       # Get files created by release script
       - name: Get zip-tarball (Windows_intel)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: zip-tarball
               path: ${{ github.workspace }}
@@ -477,11 +574,15 @@ jobs:
           cmake --workflow --preset=${{ inputs.preset_name }}-win-Intel --fresh
         shell: pwsh
 
-      - name: Publish binary (Windows_intel)
-        id: publish-ctest-binary
+      - name: Create build folders (Windows_intel)
         run: |
           mkdir "${{ runner.workspace }}/build"
           mkdir "${{ runner.workspace }}/build/hdf5"
+        shell: bash
+
+      - name: Publish binary (Windows_intel)
+        id: publish-ctest-binary
+        run: |
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING_LBNL_HDF5 -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-Intel/README.md -Destination ${{ runner.workspace }}/build/hdf5/
@@ -493,8 +594,6 @@ jobs:
       - name: Publish msi binary (Windows_intel)
         id: publish-ctest-msi-binary
         run: |
-          mkdir "${{ runner.workspace }}/build"
-          mkdir "${{ runner.workspace }}/build/hdf5"
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/${{ steps.set-file-base.outputs.SOURCE_BASE }}/COPYING_LBNL_HDF5 -Destination ${{ runner.workspace }}/build/hdf5/
           Copy-Item -Path ${{ runner.workspace }}/hdf5/build/${{ inputs.preset_name }}-Intel/README.md -Destination ${{ runner.workspace }}/build/hdf5/
@@ -557,7 +656,7 @@ jobs:
 
       # Get files created by release script
       - name: Get tgz-tarball (Linux_intel)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-tarball
               path: ${{ github.workspace }}
diff --git a/.github/workflows/main-cmake.yml b/.github/workflows/main-cmake.yml
index 8c939ae23b1..8dc5fa1176d 100644
--- a/.github/workflows/main-cmake.yml
+++ b/.github/workflows/main-cmake.yml
@@ -312,6 +312,14 @@ jobs:
         if:  ${{ (matrix.os == 'ubuntu-latest') && (inputs.thread_safety != 'TS') && (inputs.concurrent != 'CC') }}
 
       - name: Save published binary (Mac)
+        uses: actions/upload-artifact@v4
+        with:
+            name: tgz-osx13-${{ inputs.build_mode }}-binary
+            path: ${{ runner.workspace }}/build/HDF5-*-Darwin.tar.gz
+            if-no-files-found: error # 'warn' or 'ignore' are also available, defaults to `warn`
+        if: ${{ (matrix.os == 'macos-13') && (inputs.thread_safety != 'TS') }}
+
+      - name: Save published binary (Mac_latest)
         uses: actions/upload-artifact@v4
         with:
               name: tgz-osx-${{ inputs.build_mode }}-binary
diff --git a/.github/workflows/publish-branch.yml b/.github/workflows/publish-branch.yml
index 1ee8ee22bea..1e5b99bd0b0 100644
--- a/.github/workflows/publish-branch.yml
+++ b/.github/workflows/publish-branch.yml
@@ -12,8 +12,9 @@ on:
         description: 'hdf5 target bucket directory'
         type: string
         required: true
-    permissions:
-      contents: read
+
+permissions:
+  contents: read
 
 jobs:
   publish-tag:
diff --git a/.github/workflows/publish-release.yml b/.github/workflows/publish-release.yml
index d7c7fd091d1..c153d217d87 100644
--- a/.github/workflows/publish-release.yml
+++ b/.github/workflows/publish-release.yml
@@ -8,12 +8,17 @@ on:
         description: 'HDF5 Release version tag'
         type: string
         required: true
+      file_name:
+        description: 'HDF5 Release file name base'
+        type: string
+        required: true
       target_dir:
         description: 'HDF5 target bucket directory'
         type: string
         required: true
-    permissions:
-      contents: read
+
+permissions:
+  contents: read
 
 jobs:
   publish-tag:
@@ -47,9 +52,9 @@ jobs:
                 aws s3 sync ./HDF5 s3://${{ secrets.AWS_S3_BUCKET }}/${{ vars.TARGET_PATH }}/${{ inputs.target_dir }}/downloads --delete
 
         - name: Uncompress source (Linux)
-          run: tar -zxvf ${{ github.workspace }}/HDF5/${{ inputs.use_hdf }}.doxygen.tar.gz
+          run: unzip ${{ github.workspace }}/HDF5/${{ inputs.file_name }}.doxygen.zip
 
         - name: Sync userguide to S3 bucket
           run: |
-                aws s3 sync ./HDF5/doxygen s3://${{ secrets.AWS_S3_BUCKET }}/${{ vars.TARGET_PATH }}/${{ inputs.target_dir }}/documentation/doxygen --delete
+                aws s3 sync ./${{ inputs.file_name }}.doxygen s3://${{ secrets.AWS_S3_BUCKET }}/${{ vars.TARGET_PATH }}/${{ inputs.target_dir }}/documentation/doxygen --delete
 
diff --git a/.github/workflows/release-files.yml b/.github/workflows/release-files.yml
index 24c40786aec..b438e2dfc09 100644
--- a/.github/workflows/release-files.yml
+++ b/.github/workflows/release-files.yml
@@ -73,7 +73,7 @@ jobs:
 
       # Get files created by tarball script
       - name: Get doxygen (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: docs-doxygen
               path: ${{ github.workspace }}/${{ steps.get-file-base.outputs.FILE_BASE }}.doxygen
@@ -82,94 +82,94 @@ jobs:
         run: zip -r ${{ steps.get-file-base.outputs.FILE_BASE }}.doxygen.zip ./${{ steps.get-file-base.outputs.FILE_BASE }}.doxygen
 
       - name: Get tgz-tarball (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-tarball
               path: ${{ github.workspace }}
 
       - name: Get zip-tarball (Windows)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: zip-tarball
               path: ${{ github.workspace }}
 
       # Get files created by cmake-ctest script
       - name: Get published binary (Windows)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: zip-vs2022_cl-binary
               path: ${{ github.workspace }}
 
       - name: Get published msi binary (Windows)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: msi-vs2022_cl-binary
               path: ${{ github.workspace }}
 
       - name: Get published binary (MacOS)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-osx-binary
               path: ${{ github.workspace }}
 
       - name: Get published binary (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-ubuntu-2204_gcc-binary
               path: ${{ github.workspace }}
 
       - name: Get published deb binary (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: deb-ubuntu-2204_gcc-binary
               path: ${{ github.workspace }}
 
       - name: Get published rpm binary (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: rpm-ubuntu-2204_gcc-binary
               path: ${{ github.workspace }}
 
       - name: Get published binary (Linux S3)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-ubuntu-2204_gcc_s3-binary
               path: ${{ github.workspace }}
 
       - name: Get published binary (Windows_intel)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: zip-vs2022_intel-binary
               path: ${{ github.workspace }}
 
       - name: Get published msi binary (Windows_intel)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: msi-vs2022_intel-binary
               path: ${{ github.workspace }}
 
       - name: Get published binary (Linux_intel)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-ubuntu-2204_intel-binary
               path: ${{ github.workspace }}
 
       - name: Get published abi reports (Linux)
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: abi-reports
               path: ${{ github.workspace }}
 
       - name: Get published nonversioned source (tgz)
         if: ${{ (inputs.use_environ == 'release') }}
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: tgz-tarball-nover
               path: ${{ github.workspace }}
 
       - name: Get published nonversioned source (zip)
         if: ${{ (inputs.use_environ == 'release') }}
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: zip-tarball-nover
               path: ${{ github.workspace }}
@@ -202,7 +202,7 @@ jobs:
           echo "${{ steps.get-file-base.outputs.FILE_BASE }}" > ./last-file.txt
 
       - name: Get NEWSLETTER
-        uses: actions/download-artifact@65a9edc5881444af0b9093a5e628f2fe47ea3b2e # v4.1.7
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
               name: NEWSLETTER
               path: ${{ github.workspace }}
@@ -214,7 +214,7 @@ jobs:
       - name: PreRelease tag
         id: create_prerelease
         if: ${{ (inputs.use_environ == 'snapshots') }}
-        uses: softprops/action-gh-release@a74c6b72af54cfa997e81df42d94703d6313a2d0 # v2.0.6
+        uses: softprops/action-gh-release@c062e08bd532815e2082a85e87e3ef29c3e6d191 # v2.0.8
         with:
           tag_name: "${{ inputs.use_tag }}"
           prerelease: true
@@ -241,7 +241,7 @@ jobs:
       - name: Release tag
         id: create_release
         if: ${{ (inputs.use_environ == 'release') }}
-        uses: softprops/action-gh-release@a74c6b72af54cfa997e81df42d94703d6313a2d0 # v2.0.6
+        uses: softprops/action-gh-release@c062e08bd532815e2082a85e87e3ef29c3e6d191 # v2.0.8
         with:
           tag_name: "${{ inputs.use_tag }}"
           prerelease: false
diff --git a/.github/workflows/scorecard.yml b/.github/workflows/scorecard.yml
index b826ee51164..e67627fd885 100644
--- a/.github/workflows/scorecard.yml
+++ b/.github/workflows/scorecard.yml
@@ -37,7 +37,7 @@ jobs:
           persist-credentials: false
 
       - name: "Run analysis"
-        uses: ossf/scorecard-action@dc50aa9510b46c811795eb24b2f1ba02a914e534 # v2.3.3
+        uses: ossf/scorecard-action@62b2cac7ed8198b15735ed49ab1e5cf35480ba46 # v2.4.0
         with:
           results_file: results.sarif
           results_format: sarif
@@ -67,6 +67,6 @@ jobs:
 
       # Upload the results to GitHub's code scanning dashboard.
       - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@b611370bb5703a7efb587f9d136a52ea24c5c38c # v3.25.11
+        uses: github/codeql-action/upload-sarif@afb54ba388a7dca6ecae48f608c4ff05ff4cc77a # v3.25.15
         with:
           sarif_file: results.sarif
diff --git a/HDF5Examples/C/H5G/test-pc.sh b/HDF5Examples/C/H5G/test-pc.sh
index 4c996a45a58..4cff7780fe7 100755
--- a/HDF5Examples/C/H5G/test-pc.sh
+++ b/HDF5Examples/C/H5G/test-pc.sh
@@ -1,7 +1,6 @@
 #! /bin/sh
 #
 # Copyright by The HDF Group.
-# Copyright by the Board of Trustees of the University of Illinois.
 # All rights reserved.
 #
 # This file is part of HDF5.  The full HDF5 copyright notice, including
diff --git a/HDF5Examples/C/H5T/test-pc.sh b/HDF5Examples/C/H5T/test-pc.sh
index 5a773f6097b..69c948759d2 100755
--- a/HDF5Examples/C/H5T/test-pc.sh
+++ b/HDF5Examples/C/H5T/test-pc.sh
@@ -1,7 +1,6 @@
 #! /bin/sh
 #
 # Copyright by The HDF Group.
-# Copyright by the Board of Trustees of the University of Illinois.
 # All rights reserved.
 #
 # This file is part of HDF5.  The full HDF5 copyright notice, including
diff --git a/HDF5Examples/CMakePresets.json b/HDF5Examples/CMakePresets.json
index d9fdd04201a..1dc335ea715 100644
--- a/HDF5Examples/CMakePresets.json
+++ b/HDF5Examples/CMakePresets.json
@@ -49,6 +49,8 @@
       "description": "MSVC Standard Config for x64 (Release)",
       "inherits": [
         "ci-x64-Release-MSVC",
+        "ci-StdJava",
+        "ci-StdFortran",
         "ci-StdShar"
       ]
     },
@@ -57,6 +59,8 @@
       "description": "Clang Standard Config for x64 (Release)",
       "inherits": [
         "ci-x64-Release-Clang",
+        "ci-StdJava",
+        "ci-StdFortran",
         "ci-StdShar"
       ]
     },
@@ -65,6 +69,8 @@
       "description": "GNUC Standard Config for x64 (Release)",
       "inherits": [
         "ci-x64-Release-GNUC",
+        "ci-StdJava",
+        "ci-StdFortran",
         "ci-StdShar"
       ]
     },
@@ -73,6 +79,8 @@
       "description": "Intel Standard Config for x64 (Release)",
       "inherits": [
         "ci-x64-Release-Intel",
+        "ci-StdJava",
+        "ci-StdFortran",
         "ci-StdShar"
       ]
     }
@@ -98,7 +106,7 @@
       "name": "ci-StdShar-GNUC",
       "description": "GNUC Standard Build for x64 (Release)",
       "configurePreset": "ci-StdShar-GNUC",
-      "verbose": false,
+      "verbose": true,
       "inherits": [
         "ci-x64-Release-GNUC"
       ]
@@ -107,7 +115,7 @@
       "name": "ci-StdShar-Intel",
       "description": "Intel Standard Build for x64 (Release)",
       "configurePreset": "ci-StdShar-Intel",
-      "verbose": false,
+      "verbose": true,
       "inherits": [
         "ci-x64-Release-Intel"
       ]
diff --git a/HDF5Examples/FORTRAN/H5G/test-pc.sh b/HDF5Examples/FORTRAN/H5G/test-pc.sh
index 90b02f117dd..29781f3565d 100755
--- a/HDF5Examples/FORTRAN/H5G/test-pc.sh
+++ b/HDF5Examples/FORTRAN/H5G/test-pc.sh
@@ -1,7 +1,6 @@
 #! /bin/sh
 #
 # Copyright by The HDF Group.
-# Copyright by the Board of Trustees of the University of Illinois.
 # All rights reserved.
 #
 # This file is part of HDF5.  The full HDF5 copyright notice, including
diff --git a/HDF5Examples/FORTRAN/H5T/test-pc.sh b/HDF5Examples/FORTRAN/H5T/test-pc.sh
index c11fa1d8297..12163a6f1f4 100755
--- a/HDF5Examples/FORTRAN/H5T/test-pc.sh
+++ b/HDF5Examples/FORTRAN/H5T/test-pc.sh
@@ -1,7 +1,6 @@
 #! /bin/sh
 #
 # Copyright by The HDF Group.
-# Copyright by the Board of Trustees of the University of Illinois.
 # All rights reserved.
 #
 # This file is part of HDF5.  The full HDF5 copyright notice, including
diff --git a/HDF5Examples/config/cmake/HDFExampleMacros.cmake b/HDF5Examples/config/cmake/HDFExampleMacros.cmake
index c5e7b70c6bb..9888c06d36a 100644
--- a/HDF5Examples/config/cmake/HDFExampleMacros.cmake
+++ b/HDF5Examples/config/cmake/HDFExampleMacros.cmake
@@ -191,9 +191,17 @@ macro (HDF5_SUPPORT)
         endif ()
         set (H5EX_HDF5_DUMP_EXECUTABLE $<TARGET_FILE:${HDF5_NAMESPACE}h5dump>)
       else ()
+        if (HDF5_BUILD_MODE)
+          string (TOUPPER "_${HDF5_BUILD_MODE}" UPPER_BUILD_TYPE)
+        elseif (HDF_CFG_NAME)
+          string (TOUPPER "_${HDF_CFG_NAME}" UPPER_BUILD_TYPE)
+        else ()
+          set (UPPER_BUILD_TYPE "")
+        endif ()
+        get_filename_component (_LIBRARY_PATH ${HDF5_INCLUDE_DIR} DIRECTORY)
+        set (HDF5_LIBRARY_PATH "${_LIBRARY_PATH}/lib")
         if (USE_SHARED_LIBS AND HDF5_shared_C_FOUND)
           set (H5EX_HDF5_LINK_LIBS ${H5EX_HDF5_LINK_LIBS} ${HDF5_C_SHARED_LIBRARY})
-          set (HDF5_LIBRARY_PATH ${PACKAGE_PREFIX_DIR}/lib)
         else ()
           set (H5EX_HDF5_LINK_LIBS ${H5EX_HDF5_LINK_LIBS} ${HDF5_C_STATIC_LIBRARY})
         endif ()
@@ -227,20 +235,11 @@ macro (HDF5_SUPPORT)
         if (HDF_BUILD_JAVA AND HDF5_Java_FOUND)
           if (${HDF5_BUILD_JAVA})
             set (CMAKE_JAVA_INCLUDE_PATH "${CMAKE_JAVA_INCLUDE_PATH};${HDF5_JAVA_INCLUDE_DIRS}")
-            if (HDF5_BUILD_MODE)
-              string(TOUPPER "${HDF5_BUILD_MODE}" UPPER_BUILD_TYPE)
-              get_target_property(libsoname ${HDF5_JAVA_LIBRARY} IMPORTED_SONAME_${UPPER_BUILD_TYPE})
-            elseif (HDF_CFG_NAME)
-              string(TOUPPER "${HDF_CFG_NAME}" UPPER_BUILD_TYPE)
-              get_target_property(libsoname ${HDF5_JAVA_LIBRARY} IMPORTED_SONAME_${UPPER_BUILD_TYPE})
-            else()
-              get_target_property(libsoname ${HDF5_JAVA_LIBRARY} IMPORTED_SONAME)
-            endif()
+            get_target_property (libsoname ${HDF5_JAVA_LIBRARY} IMPORTED_SONAME${UPPER_BUILD_TYPE})
             get_filename_component (libname ${libsoname} NAME_WE)
             string (REGEX REPLACE "^lib" "" libname ${libname})
             message (STATUS "HDF5 lib:${HDF5_JAVA_LIBRARY} OR ${libsoname} OR ${libname}")
             set (H5EX_JAVA_LIBRARY ${libname})
-#            set (H5EX_JAVA_LIBRARY $<TARGET_FILE_BASE_NAME:${HDF5_JAVA_LIBRARY}>)
             set (H5EX_JAVA_LIBRARIES ${HDF5_JAVA_LIBRARY})
             message (STATUS "HDF5 lib:${H5EX_JAVA_LIBRARY} jars:${HDF5_JAVA_INCLUDE_DIRS}}")
           else ()
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 4499fa67292..58a0eccb840 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1137,8 +1137,7 @@ if (BUILD_SHARED_LIBS)
   TARGET_C_PROPERTIES (${HDF5_LIBSH_TARGET} SHARED)
   target_link_libraries (${HDF5_LIBSH_TARGET}
       PRIVATE ${LINK_LIBS} ${LINK_COMP_LIBS}
-              "$<$<OR:$<BOOL:${HDF5_ENABLE_THREADSAFE}>,$<BOOL:${HDF5_ENABLE_SUBFILING_VFD}>>:Threads::Threads>"
-      PUBLIC "$<$<NOT:$<PLATFORM_ID:Windows>>:${CMAKE_DL_LIBS}>" "$<$<BOOL:${HDF5_ENABLE_PARALLEL}>:MPI::MPI_C>"
+      PUBLIC "$<$<NOT:$<PLATFORM_ID:Windows>>:${CMAKE_DL_LIBS}>" "$<$<BOOL:${HDF5_ENABLE_PARALLEL}>:MPI::MPI_C>" "$<$<OR:$<BOOL:${HDF5_ENABLE_THREADS}>,$<BOOL:${HDF5_ENABLE_SUBFILING_VFD}>>:Threads::Threads>"
   )
   set_global_variable (HDF5_LIBRARIES_TO_EXPORT "${HDF5_LIBRARIES_TO_EXPORT};${HDF5_LIBSH_TARGET}")
   H5_SET_LIB_OPTIONS (${HDF5_LIBSH_TARGET} ${HDF5_LIB_NAME} SHARED "LIB")
diff --git a/src/H5TSatomic.h b/src/H5TSatomic.h
index 1d8011c577b..478760e8c4d 100644
--- a/src/H5TSatomic.h
+++ b/src/H5TSatomic.h
@@ -344,4 +344,4 @@ H5TS_atomic_compare_exchange_strong_voidp(H5TS_atomic_voidp_t *obj, void **expec
     return ret_value;
 } /* end H5TS_atomic_compare_exchange_strong_voidp() */
 
-#endif /* H5_HAVE_THREADS */
+#endif /* H5_HAVE_STDATOMIC_H */
diff --git a/src/H5Tcommit.c b/src/H5Tcommit.c
index 56b22042d66..d64c4e82439 100644
--- a/src/H5Tcommit.c
+++ b/src/H5Tcommit.c
@@ -59,6 +59,7 @@ static herr_t H5T__commit_api_common(hid_t loc_id, const char *name, hid_t type_
 static hid_t  H5T__open_api_common(hid_t loc_id, const char *name, hid_t tapl_id, void **token_ptr,
                                    H5VL_object_t **_vol_obj_ptr);
 static H5T_t *H5T__open_oid(const H5G_loc_t *loc);
+static herr_t H5T_destruct_datatype(void *datatype, H5VL_t *vol_connector);
 
 /*********************/
 /* Public Variables */
@@ -662,7 +663,7 @@ H5T__open_api_common(hid_t loc_id, const char *name, hid_t tapl_id, void **token
 done:
     /* Cleanup on error */
     if (H5I_INVALID_HID == ret_value)
-        if (dt && H5VL_datatype_close(*vol_obj_ptr, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL) < 0)
+        if (dt && H5T_destruct_datatype(dt, (*vol_obj_ptr)->connector) < 0)
             HDONE_ERROR(H5E_DATATYPE, H5E_CLOSEERROR, H5I_INVALID_HID, "unable to release datatype");
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1260,6 +1261,41 @@ H5T_construct_datatype(H5VL_object_t *vol_obj)
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5T_construct_datatype() */
 
+/*-------------------------------------------------------------------------
+ * Function:    H5T_destruct_datatype
+ *
+ * Purpose:     Helper function to free a committed datatype object that
+ *              hasn't yet been wrapped within a VOL object. This usually
+ *              happens when a failure occurs during opening a committed
+ *              datatype. When this happens, the datatype must be wrapped
+ *              inside a temporary VOL object in order to route the close
+ *              operation through the stack of VOL connectors.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T_destruct_datatype(void *datatype, H5VL_t *vol_connector)
+{
+    H5VL_object_t *vol_obj   = NULL;
+    herr_t         ret_value = FAIL;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if (NULL == (vol_obj = H5VL_create_object(datatype, vol_connector)))
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTALLOC, FAIL, "can't create VOL object for committed datatype");
+
+    if (H5VL_datatype_close(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL) < 0)
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CLOSEERROR, FAIL, "unable to release datatype");
+
+done:
+    if (vol_obj && H5VL_free_object(vol_obj) < 0)
+        HDONE_ERROR(H5E_DATATYPE, H5E_CANTFREE, FAIL, "can't free VOL object");
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T_destruct_datatype() */
+
 /*-------------------------------------------------------------------------
  * Function:    H5T_get_named_type
  *
diff --git a/src/H5VLint.c b/src/H5VLint.c
index f3648b14a87..295b71e2854 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -586,6 +586,12 @@ H5VL__new_vol_obj(H5I_type_t type, void *object, H5VL_t *vol_connector, bool wra
     if (NULL == ret_value) {
         if (conn_rc_incr && H5VL_conn_dec_rc(vol_connector) < 0)
             HDONE_ERROR(H5E_VOL, H5E_CANTDEC, NULL, "unable to decrement ref count on VOL connector");
+
+        if (new_vol_obj) {
+            if (wrap_obj && new_vol_obj->data)
+                (void)H5VL_object_unwrap(new_vol_obj);
+            (void)H5FL_FREE(H5VL_object_t, new_vol_obj);
+        }
     } /* end if */
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -706,7 +712,7 @@ H5VL_register(H5I_type_t type, void *object, H5VL_t *vol_connector, bool app_ref
     /* Set up VOL object for the passed-in data */
     /* (Does not wrap object, since it's from a VOL callback) */
     if (NULL == (vol_obj = H5VL__new_vol_obj(type, object, vol_connector, false)))
-        HGOTO_ERROR(H5E_VOL, H5E_CANTCREATE, FAIL, "can't create VOL object");
+        HGOTO_ERROR(H5E_VOL, H5E_CANTCREATE, H5I_INVALID_HID, "can't create VOL object");
 
     /* Register VOL object as _object_ type, for future object API calls */
     if ((ret_value = H5I_register(type, vol_obj, app_ref)) < 0)
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index c6e063a3ddd..9c3f28a01d1 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -575,12 +575,9 @@ target_include_directories (ttsafe PRIVATE "${HDF5_SRC_INCLUDE_DIRS};${HDF5_SRC_
 if (NOT BUILD_SHARED_LIBS)
   TARGET_C_PROPERTIES (ttsafe STATIC)
   target_link_libraries (ttsafe PRIVATE ${HDF5_TEST_LIB_TARGET})
-  if (NOT WIN32)
-    target_link_libraries (ttsafe PRIVATE "$<$<BOOL:${HDF5_ENABLE_THREADSAFE}>:Threads::Threads>")
-  endif ()
 else ()
   TARGET_C_PROPERTIES (ttsafe SHARED)
-  target_link_libraries (ttsafe PRIVATE ${HDF5_TEST_LIBSH_TARGET} "$<$<BOOL:${HDF5_ENABLE_THREADSAFE}>:Threads::Threads>")
+  target_link_libraries (ttsafe PRIVATE ${HDF5_TEST_LIBSH_TARGET})
 endif ()
 set_target_properties (ttsafe PROPERTIES FOLDER test)
 
diff --git a/test/testframe.c b/test/testframe.c
index ff12413a62e..50daede8eea 100644
--- a/test/testframe.c
+++ b/test/testframe.c
@@ -590,7 +590,7 @@ TestErrPrintf(const char *format, ...)
  * Set (control) which test will be tested.
  * SKIPTEST: skip this test
  * ONLYTEST: do only this test
- * BEGINETEST: skip all tests before this test
+ * BEGINTEST: skip all tests before this test
  *
  */
 void
diff --git a/test/ttsafe_rec_rw_lock.c b/test/ttsafe_rec_rw_lock.c
new file mode 100644
index 00000000000..f7230af3d9d
--- /dev/null
+++ b/test/ttsafe_rec_rw_lock.c
@@ -0,0 +1,1137 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/********************************************************************
+ *
+ * Test the correctness of the recursive R/W lock in the HDF5 library
+ * -------------------------------------------------------------
+ *
+ * Test the recursive R/W lock in isolation, using a combination of
+ * error return values and statistics collected by the recursive
+ * R/W lock to detect any failures.
+ *
+ * No file is created.
+ *
+ * Multiple threads are created, and allowed to compete for the lock.
+ * The number of threads, and the number of times they obtain the
+ * lock depends on the express test level.
+ *
+ ********************************************************************/
+
+#include "ttsafe.h"
+
+#ifdef H5_HAVE_THREADS
+#ifndef H5_HAVE_WIN_THREADS
+
+#define MAX_NUM_THREADS 32
+#define MAX_LOCK_CYCLES (1000 * 1000)
+
+/* structure used to configure test threads in the recursive
+ * R/W/ lock tests.
+ */
+/***********************************************************************
+ *
+ * Structure rec_rw_lock_test_udata_t
+ *
+ * Arrays of instances of rec_rw_lock_test_udata_t are used to configure
+ * the threads used to test the recursive R/W lock, and to collect
+ * statistics on their behaviour.  These statistics are aggregated and
+ * used to cross-check the statistics collected by the recursive R/W
+ * lock proper.
+ *
+ * The fields of the structure are discussed below:
+ *
+ * rw_lock: Pointer to the recursive R/W under test.
+ *
+ * target_rd_lock_cycles: The number of times the test thread is
+ *              required to obtain and drop the read lock.  Note
+ *              that this value restricts the number of initial
+ *              read locks only.  Additional recursive locks are
+ *              possible -- see max_recursive_lock_depth below.
+ *
+ * target_wr_lock_cycles: The number of times the test thread is
+ *              required to obtain and drop the write lock.  Note
+ *              that this value restricts the number of initial
+ *              write locks only.  Additional recursive locks are
+ *              possible -- see max_recursive_lock_depth below.
+ *
+ * max_recursive_lock_depth: Once a test thread gains a lock, it does
+ *              random recursive leocks and unlocks until it happens
+ *              to drop the lock.  The max_recursive_lock_depth
+ *              places an upper bound on the net number of locks.
+ *              Any attempt exceed this limit is converted into
+ *              an unlock.
+ *
+ * The remaining fields are used for statistics collection.  They are
+ * thread specific versions of the fields of the same name in
+ * H5TS_rw_lock_stats_t.  See the header comment for that
+ * structure (in H5TSprivate.h) for further details.
+ *
+ ***********************************************************************/
+typedef struct rec_rw_lock_test_udata_t {
+
+    /* thread control fields */
+    H5TS_rw_lock_t *rw_lock;
+    int32_t         target_rd_lock_cycles;
+    int32_t         target_wr_lock_cycles;
+    int32_t         max_recursive_lock_depth;
+
+    /* thread stats fields */
+    int64_t read_locks_granted;
+    int64_t read_locks_released;
+    int64_t real_read_locks_granted;
+    int64_t real_read_locks_released;
+    int64_t write_locks_granted;
+    int64_t write_locks_released;
+    int64_t real_write_locks_granted;
+    int64_t real_write_locks_released;
+
+} rec_rw_lock_test_udata_t;
+
+/*
+ **********************************************************************
+ * tts_rw_lock_smoke_check_test_thread
+ *
+ * Perform a sequence of recursive read and/or write locks on the
+ * target recursive R/W lock as directed by the supplied user data.
+ * Record all operations in the user data for later cross-checking
+ * with the statistics maintained by the recursive R/W lock.
+ *
+ * Note: while the number of read and/or write locks is fixed, the
+ * number of _recursive_ lock and unlock calls is random, as is the
+ * order of the read and write locks, if both are enabled.
+ *
+ **********************************************************************
+ */
+static H5TS_THREAD_RETURN_TYPE
+tts_rw_lock_smoke_check_test_thread(void *_udata)
+{
+    hbool_t                   read;
+    int32_t                   rec_lock_depth = 0;
+    int32_t                   max_rec_lock_depth;
+    int32_t                   rd_locks_remaining;
+    int32_t                   wr_locks_remaining;
+    herr_t                    result;
+    H5TS_rw_lock_t           *rw_lock;
+    rec_rw_lock_test_udata_t *udata = (rec_rw_lock_test_udata_t *)_udata;
+
+    assert(_udata);
+    rd_locks_remaining = udata->target_rd_lock_cycles;
+    wr_locks_remaining = udata->target_wr_lock_cycles;
+    max_rec_lock_depth = udata->max_recursive_lock_depth;
+    rw_lock            = udata->rw_lock;
+
+    while (rd_locks_remaining > 0 || wr_locks_remaining > 0) {
+        if (wr_locks_remaining == 0)
+            read = TRUE;
+        else if (rd_locks_remaining == 0)
+            read = FALSE;
+        else {
+            if ((rand() % 2) == 0)
+                read = TRUE;
+            else
+                read = FALSE;
+        }
+
+        if (read) {
+            result = H5TS__rw_rdlock(rw_lock);
+            CHECK_I(result, "H5TS__rw_rdlock");
+
+            udata->read_locks_granted++;
+            udata->real_read_locks_granted++;
+            rd_locks_remaining--;
+            rec_lock_depth = 1;
+
+            while (rec_lock_depth > 0) {
+                if (rec_lock_depth >= max_rec_lock_depth || (rand() % 2) == 0) {
+                    result = H5TS__rw_unlock(rw_lock);
+                    CHECK_I(result, "H5TS__rw_unlock");
+
+                    rec_lock_depth--;
+                    udata->read_locks_released++;
+                }
+                else {
+                    result = H5TS__rw_rdlock(rw_lock);
+                    CHECK_I(result, "H5TS__rw_rdlock");
+
+                    rec_lock_depth++;
+                    udata->read_locks_granted++;
+                }
+            }
+
+            udata->real_read_locks_released++;
+        }
+        else {
+            result = H5TS__rw_wrlock(rw_lock);
+            CHECK_I(result, "H5TS__rw_wrlock");
+
+            udata->write_locks_granted++;
+            udata->real_write_locks_granted++;
+            wr_locks_remaining--;
+            rec_lock_depth = 1;
+
+            while (rec_lock_depth > 0) {
+                if (rec_lock_depth >= max_rec_lock_depth || (rand() % 2) == 0) {
+                    result = H5TS__rw_unlock(rw_lock);
+                    CHECK_I(result, "H5TS__rw_unlock");
+
+                    rec_lock_depth--;
+                    udata->write_locks_released++;
+                }
+                else {
+                    result = H5TS__rw_wrlock(rw_lock);
+                    CHECK_I(result, "H5TS__rw_wrlock");
+
+                    rec_lock_depth++;
+                    udata->write_locks_granted++;
+                }
+            }
+
+            udata->real_write_locks_released++;
+        }
+    }
+
+    return (H5TS_thread_ret_t)0;
+} /* end tts_rw_lock_smoke_check_test_thread() */
+
+/*
+ **********************************************************************
+ * tts_rec_rw_lock_smoke_check_1
+ *
+ * Single thread test to verify basic functionality and error
+ * rejection of the recursive R/W lock.
+ *
+ *  1) Initialize an instance of the recursive R/W lock.
+ *
+ *  2) Obtain a read lock.
+ *
+ *  3) Drop the read lock.
+ *
+ *  4) Verify the expected stats, and then reset them.
+ *
+ *  5) Obtain a read lock.
+ *
+ *  6) Obtain the read lock a second time.
+ *
+ *  7) Drop the read lock.
+ *
+ *  8) Drop the read lock a second time.
+ *
+ *  9) Verify the expected stats, and then reset them.
+ *
+ * 10) Obtain a write lock.
+ *
+ * 11) Drop the write lock.
+ *
+ * 12) Verify the expected stats, and then reset them.
+ *
+ * 13) Obtain a write lock.
+ *
+ * 14) Obtain the write lock a second time.
+ *
+ * 15) Drop the write lock.
+ *
+ * 16) Drop the write lock a second time.
+ *
+ * 17) Verify the expected stats, and then reset them.
+ *
+ * 18) Obtain a write lock.
+ *
+ * 19) Attempt to obtain a read lock -- should fail.
+ *
+ * 20) Drop the write lock.
+ *
+ * 21) Obtain a read lock.
+ *
+ * 22) Attempt to obtain a write lock -- should fail.
+ *
+ * 23) Drop the read lock.
+ *
+ * 24) Verify the expected stats, and then reset them.
+ *
+ * 25) Shut down the recursive R/W lock.
+ *
+ **********************************************************************
+ */
+void
+tts_rec_rw_lock_smoke_check_1(void)
+{
+    herr_t result;
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    H5TS_rw_lock_stats_t stats;
+#endif
+    H5TS_rw_lock_t rec_rw_lock;
+
+    /* 1) Initialize an instance of the recursive R/W lock. */
+    result = H5TS__rw_lock_init(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_init");
+
+    /* 2) Obtain a read lock. */
+    result = H5TS__rw_rdlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_rdlock");
+
+    /* 3) Drop the read lock. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* 4) Verify the expected stats, and then reset them. */
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    result = H5TS__rw_lock_reset_stats(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_reset_stats");
+
+    /* clang-format makes this conditional unreadable, so turn it off. */
+    /* clang-format off */
+    if (stats.read_locks_granted             != 1 ||
+        stats.read_locks_released            != 1 ||
+        stats.real_read_locks_granted        != 1 ||
+        stats.real_read_locks_released       != 1 ||
+        stats.max_read_locks                 != 1 ||
+        stats.max_read_lock_recursion_depth  != 1 ||
+        stats.read_locks_delayed             != 0 ||
+        stats.write_locks_granted            != 0 ||
+        stats.write_locks_released           != 0 ||
+        stats.real_write_locks_granted       != 0 ||
+        stats.real_write_locks_released      != 0 ||
+        stats.max_write_locks                != 0 ||
+        stats.max_write_lock_recursion_depth != 0 ||
+        stats.write_locks_delayed            != 0 ||
+        stats.max_write_locks_pending        != 0 ) {
+
+        TestErrPrintf("Unexpected recursive R/W lock stats -- 1");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+    }
+    /* clang-format on */
+#endif
+
+    /* 5) Obtain a read lock. */
+    result = H5TS__rw_rdlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_rdlock");
+
+    /* 6) Obtain the read lock a second time. */
+    result = H5TS__rw_rdlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_rdlock");
+
+    /* 7) Drop the read lock. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+    /* 8) Drop the read lock a second time. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* 9) Verify the expected stats, and then reset them. */
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    result = H5TS__rw_lock_reset_stats(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_reset_stats");
+
+    /* clang-format makes this conditional unreadable, so turn it off. */
+    /* clang-format off */
+    if (stats.read_locks_granted             != 2 ||
+        stats.read_locks_released            != 2 ||
+        stats.real_read_locks_granted        != 1 ||
+        stats.real_read_locks_released       != 1 ||
+        stats.max_read_locks                 != 1 ||
+        stats.max_read_lock_recursion_depth  != 2 ||
+        stats.read_locks_delayed             != 0 ||
+        stats.write_locks_granted            != 0 ||
+        stats.write_locks_released           != 0 ||
+        stats.real_write_locks_granted       != 0 ||
+        stats.real_write_locks_released      != 0 ||
+        stats.max_write_locks                != 0 ||
+        stats.max_write_lock_recursion_depth != 0 ||
+        stats.write_locks_delayed            != 0 ||
+        stats.max_write_locks_pending        != 0 ) {
+
+        TestErrPrintf("Unexpected recursive R/W lock stats -- 2");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+    }
+    /* clang-format on */
+#endif
+
+    /* 10) Obtain a write lock. */
+    result = H5TS__rw_wrlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_wrlock");
+
+    /* 11) Drop the write lock. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* 12) Verify the expected stats, and then reset them. */
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    result = H5TS__rw_lock_reset_stats(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_reset_stats");
+
+    /* clang-format makes this conditional unreadable, so turn it off. */
+    /* clang-format off */
+    if (stats.read_locks_granted             != 0 ||
+        stats.read_locks_released            != 0 ||
+        stats.real_read_locks_granted        != 0 ||
+        stats.real_read_locks_released       != 0 ||
+        stats.max_read_locks                 != 0 ||
+        stats.max_read_lock_recursion_depth  != 0 ||
+        stats.read_locks_delayed             != 0 ||
+        stats.write_locks_granted            != 1 ||
+        stats.write_locks_released           != 1 ||
+        stats.real_write_locks_granted       != 1 ||
+        stats.real_write_locks_released      != 1 ||
+        stats.max_write_locks                != 1 ||
+        stats.max_write_lock_recursion_depth != 1 ||
+        stats.write_locks_delayed            != 0 ||
+        stats.max_write_locks_pending        != 0 ) {
+
+        TestErrPrintf("Unexpected recursive R/W lock stats -- 3");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+    }
+    /* clang-format on */
+#endif
+
+    /* 13) Obtain a write lock. */
+    result = H5TS__rw_wrlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_wrlock");
+
+    /* 14) Obtain the write lock a second time. */
+    result = H5TS__rw_wrlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_wrlock");
+
+    /* 15) Drop the write lock. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+    /* 16) Drop the write lock a second time. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* 17) Verify the expected stats, and then reset them. */
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    result = H5TS__rw_lock_reset_stats(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_reset_stats");
+
+    /* clang-format makes this conditional unreadable, so turn it off. */
+    /* clang-format off */
+    if (stats.read_locks_granted             != 0 ||
+        stats.read_locks_released            != 0 ||
+        stats.real_read_locks_granted        != 0 ||
+        stats.real_read_locks_released       != 0 ||
+        stats.max_read_locks                 != 0 ||
+        stats.max_read_lock_recursion_depth  != 0 ||
+        stats.read_locks_delayed             != 0 ||
+        stats.write_locks_granted            != 2 ||
+        stats.write_locks_released           != 2 ||
+        stats.real_write_locks_granted       != 1 ||
+        stats.real_write_locks_released      != 1 ||
+        stats.max_write_locks                != 1 ||
+        stats.max_write_lock_recursion_depth != 2 ||
+        stats.write_locks_delayed            != 0 ||
+        stats.max_write_locks_pending        != 0 ) {
+
+        TestErrPrintf("Unexpected recursive R/W lock stats -- 4");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+    }
+    /* clang-format on */
+#endif
+
+    /* 18) Obtain a write lock. */
+    result = H5TS__rw_wrlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_wrlock");
+
+    /* 19) Attempt to obtain a read lock -- should fail. */
+    result = H5TS__rw_rdlock(&rec_rw_lock);
+    VERIFY(result, FAIL, "H5TS__rw_rdlock");
+
+    /* 20) Drop the write lock. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+    /* 21) Obtain a read lock. */
+    result = H5TS__rw_rdlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_rdlock");
+
+    /* 22) Attempt to obtain a write lock -- should fail. */
+    result = H5TS__rw_wrlock(&rec_rw_lock);
+    VERIFY(result, FAIL, "H5TS__rw_wrlock");
+
+    /* 23) Drop the read lock. */
+    result = H5TS__rw_unlock(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_unlock");
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* 24) Verify the expected stats, and then reset them. */
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    result = H5TS__rw_lock_reset_stats(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_reset_stats");
+
+    /* clang-format makes this conditional unreadable, so turn it off. */
+    /* clang-format off */
+    if (stats.read_locks_granted             != 1 ||
+        stats.read_locks_released            != 1 ||
+        stats.real_read_locks_granted        != 1 ||
+        stats.real_read_locks_released       != 1 ||
+        stats.max_read_locks                 != 1 ||
+        stats.max_read_lock_recursion_depth  != 1 ||
+        stats.read_locks_delayed             != 0 ||
+        stats.write_locks_granted            != 1 ||
+        stats.write_locks_released           != 1 ||
+        stats.real_write_locks_granted       != 1 ||
+        stats.real_write_locks_released      != 1 ||
+        stats.max_write_locks                != 1 ||
+        stats.max_write_lock_recursion_depth != 1 ||
+        stats.write_locks_delayed            != 0 ||
+        stats.max_write_locks_pending        != 0 ) {
+
+        TestErrPrintf("Unexpected recursive R/W lock stats");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+    }
+    /* clang-format on */
+#endif
+
+    /* 25) Shut down the recursive R/W lock. */
+    result = H5TS__rw_lock_destroy(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_destroy");
+} /* end tts_rec_rw_lock_smoke_check_1() */
+
+/*
+ **********************************************************************
+ * tts_rec_rw_lock_smoke_check_2 -- mob of readers
+ *
+ * Multi-threaded test to check management of multiple readers ONLY by
+ * the recursive R/W lock.  Test proceeds as follows:
+ *
+ *  1) Initialize an instance of the recursive R/W lock.
+ *
+ *  2) Setup the user data to be passed to each reader test thread.
+ *
+ *  3) Create the reader threads, each with its own user data.
+ *     Activities of the reader threads is discussed in the header
+ *     comment to tts_rw_lock_smoke_check_test_thread().
+ *
+ *  4) Wait for all threads to complete.
+ *
+ *  5) Examine the user data from the threads, to determine the
+ *     total number of real and recursive read locks and unlocks.
+ *
+ *  6) Obtain the stats from the recursive R/W lock, and compare
+ *     with the data gathered above.
+ *
+ *  7) Shut down the recursive R/W lock.
+ *
+ * The reader threads obtain and drop the read lock a specified
+ * number of times.  Once a reader has a read lock, it does random
+ * recursive read locks / unlocks until drops the read lock, and then
+ * repeats the process until the specified number of read locks have
+ * been acquired and dropped.
+ *
+ **********************************************************************
+ */
+void
+tts_rec_rw_lock_smoke_check_2(void)
+{
+    herr_t                    result;
+    int                       express_test;
+    int                       i;
+    int                       num_threads = MAX_NUM_THREADS;
+    int                       lock_cycles = MAX_LOCK_CYCLES;
+    H5TS_thread_t             threads[MAX_NUM_THREADS];
+    rec_rw_lock_test_udata_t *udata = NULL;
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    hbool_t              verbose                     = FALSE;
+    int32_t              total_target_rd_lock_cycles = 0;
+    int32_t              total_target_wr_lock_cycles = 0;
+    H5TS_rw_lock_stats_t stats;
+    H5TS_rw_lock_stats_t expected;
+#endif
+    H5TS_rw_lock_t rec_rw_lock;
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* Reset expected stats fields to zero -- we will construct the expected
+     * stats from the thread udata after completion.
+     */
+    memset(&expected, 0, sizeof(expected));
+#endif
+
+    /* Allocate the udata */
+    udata = malloc(sizeof(*udata) * MAX_NUM_THREADS);
+    if (NULL == udata) {
+        TestErrPrintf("thread udata allocation failed.\n");
+
+        /* We can't do anything without the udata, so just return */
+        return;
+    }
+
+    /* Reduce # of threads and test cycles for higher levels of express testing */
+    express_test = GetTestExpress();
+    if (express_test >= 1) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+    if (express_test >= 2) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+    if (express_test >= 3) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+
+    /* 1) Initialize an instance of the recursive R/W lock. */
+    result = H5TS__rw_lock_init(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_init");
+
+    /* 2) Setup the user data to be passed to each reader test thread. */
+    for (i = 0; i < MAX_NUM_THREADS; i++) {
+        memset(&udata[i], 0, sizeof(udata[i]));
+        udata[i].rw_lock                  = &rec_rw_lock;
+        udata[i].target_rd_lock_cycles    = lock_cycles;
+        udata[i].max_recursive_lock_depth = 10;
+    }
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    uint64_t start_time = H5_now_usec();
+#endif
+    /* 3) Create the reader threads, each with its own user data. */
+    for (i = 0; i < num_threads; i++)
+        if (H5TS_thread_create(&threads[i], tts_rw_lock_smoke_check_test_thread, &udata[i]) < 0)
+            TestErrPrintf("thread # %d did not start", i);
+
+    /* 4) Wait for all threads to complete. */
+    for (i = 0; i < num_threads; i++)
+        if (H5TS_thread_join(threads[i], NULL) < 0)
+            TestErrPrintf("thread %d failed to join", i);
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    uint64_t end_time  = H5_now_usec();
+    uint64_t elap_time = (unsigned long long)(end_time - start_time);
+    if (verbose)
+        fprintf(stdout, "elapsed usec: %" PRIu64 ", usec per lock_cycle = %" PRIu64 "\n", elap_time,
+                (elap_time / (uint64_t)lock_cycles));
+#endif
+
+    /* 5) Examine the user data from the threads, to determine the
+     *    total number of real and recursive read locks and unlocks.
+     *
+     *    First, tally up the lock entries and exits from the test threads,
+     *    and store this data in the expected recursive R/W/ lock stats..
+     *    In passing, verify that each thread has done the expected number
+     *    of locks and unlocks.  Do these as asserts -- will run checks on
+     *    aggregate data shortly.
+     */
+
+    for (i = 0; i < num_threads; i++) {
+        assert(udata[i].target_rd_lock_cycles == udata[i].real_read_locks_granted);
+        assert(udata[i].target_rd_lock_cycles == udata[i].real_read_locks_released);
+        assert(udata[i].target_wr_lock_cycles == udata[i].real_write_locks_granted);
+        assert(udata[i].target_wr_lock_cycles == udata[i].real_write_locks_released);
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+        total_target_rd_lock_cycles += udata[i].target_rd_lock_cycles;
+        total_target_wr_lock_cycles += udata[i].target_wr_lock_cycles;
+
+        expected.read_locks_granted += udata[i].read_locks_granted;
+        expected.read_locks_released += udata[i].read_locks_released;
+        expected.real_read_locks_granted += udata[i].real_read_locks_granted;
+        expected.real_read_locks_released += udata[i].real_read_locks_released;
+        expected.write_locks_granted += udata[i].write_locks_granted;
+        expected.write_locks_released += udata[i].write_locks_released;
+        expected.real_write_locks_granted += udata[i].real_write_locks_granted;
+        expected.real_write_locks_released += udata[i].real_write_locks_released;
+#endif
+    }
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* Verify that the threads executed the expected number of read and write
+     * lock cycles.  If they didn't, some thread probably encountered an error
+     * and exited early.
+     */
+    if (total_target_rd_lock_cycles != expected.real_read_locks_granted ||
+        total_target_rd_lock_cycles != expected.real_read_locks_released ||
+        total_target_wr_lock_cycles != expected.real_write_locks_granted ||
+        total_target_wr_lock_cycles != expected.real_write_locks_released)
+        TestErrPrintf("Threads reported unexpected number of locks/unlocks.\n");
+
+    /* initialize remaining non-zero fields in the expected stats */
+    expected.max_read_locks                = num_threads;
+    expected.max_read_lock_recursion_depth = 10;
+
+    /* 6) Obtain the stats from the recursive R/W lock, and compare
+     *     with the data gathered above.
+     */
+
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    /* turn off clang-format for readability */
+    /* clang-format off */
+    if (stats.read_locks_granted                 != expected.read_locks_granted ||
+            stats.read_locks_released            != expected.read_locks_released ||
+            stats.real_read_locks_granted        != expected.real_read_locks_granted ||
+            stats.real_read_locks_released       != expected.real_read_locks_released ||
+            stats.max_read_locks                  > expected.max_read_locks ||
+            stats.max_read_locks                  < 1 ||
+            stats.max_read_lock_recursion_depth   > expected.max_read_lock_recursion_depth ||
+            stats.max_read_lock_recursion_depth   < 1 ||
+            stats.read_locks_delayed             != expected.read_locks_delayed ||
+            stats.write_locks_granted            != expected.write_locks_granted ||
+            stats.write_locks_released           != expected.write_locks_released ||
+            stats.real_write_locks_granted       != expected.real_write_locks_granted ||
+            stats.real_write_locks_released      != expected.real_write_locks_released ||
+            stats.max_write_locks                != expected.max_write_locks ||
+            stats.max_write_lock_recursion_depth != expected.max_write_lock_recursion_depth ||
+            stats.write_locks_delayed            != expected.write_locks_delayed ||
+            stats.max_write_locks_pending        != expected.max_write_locks_pending) {
+        TestErrPrintf("Unexpected recursive R/W lock stats");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+        H5TS__rw_lock_print_stats("Expected stats", &expected);
+    }
+    /* clang-format on */
+
+    if (verbose)
+        H5TS__rw_lock_print_stats("mob of readers stats", &stats);
+#endif
+
+    /* 7) Shut down the recursive R/W lock. */
+    result = H5TS__rw_lock_destroy(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_destroy");
+
+    /* discard the udata if it exists */
+    if (udata)
+        free(udata);
+} /* end tts_rec_rw_lock_smoke_check_2() */
+
+/*
+ **********************************************************************
+ * tts_rec_rw_lock_smoke_check_3 -- mob of writers
+ *
+ * Multi-thread test to check management of multiple writers ONLY by
+ * the recursive R/W lock.  Test proceeds as follows:
+ *
+ *  1) Initialize an instance of the recursive R/W lock.
+ *
+ *  2) Setup the user data to be passed to each writer test thread.
+ *
+ *  3) Create the writer threads, each with its own user data.
+ *     Activities of the writer threads is discussed in the header
+ *     comment to tts_rw_lock_smoke_check_test_thread().
+ *
+ *  4) Wait for all threads to complete.
+ *
+ *  5) Examine the user data from the threads, to determine the
+ *     total number of real and recursive read locks and unlock.
+ *
+ *  6) Obtain the stats from the recursive R/W lock, and compare
+ *     with the data gathered above.
+ *
+ *  7) Shut down the recursive R/W lock.
+ *
+ * The writer threads obtain and drop the read lock a specified
+ * number of times.  Once a writeer has a write lock, it does random
+ * recursive write locks / unlocks until drops the write lock, and then
+ * repeats the process until the specified number of write locks have
+ * been acquired and dropped.
+ *
+ **********************************************************************
+ */
+void
+tts_rec_rw_lock_smoke_check_3(void)
+{
+    herr_t                    result;
+    int                       i;
+    int                       express_test;
+    int                       num_threads = MAX_NUM_THREADS;
+    int                       lock_cycles = MAX_LOCK_CYCLES;
+    H5TS_thread_t             threads[MAX_NUM_THREADS];
+    rec_rw_lock_test_udata_t *udata = NULL;
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    hbool_t              verbose                     = FALSE;
+    int32_t              total_target_rd_lock_cycles = 0;
+    int32_t              total_target_wr_lock_cycles = 0;
+    H5TS_rw_lock_stats_t stats;
+    H5TS_rw_lock_stats_t expected;
+#endif
+    H5TS_rw_lock_t rec_rw_lock;
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* Reset expected stats fields to zero -- we will construct the expected
+     * stats from the thread udata after completion.
+     */
+    memset(&expected, 0, sizeof(expected));
+#endif
+
+    /* Allocate the udata */
+    udata = malloc(sizeof(*udata) * MAX_NUM_THREADS);
+    if (udata == NULL) {
+        TestErrPrintf("thread udata allocation failed.\n");
+
+        /* We can't do anything without the udata, so just return */
+        return;
+    }
+
+    /* Reduce # of threads and test cycles for higher levels of express testing */
+    express_test = GetTestExpress();
+    if (express_test >= 1) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+    if (express_test >= 2) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+    if (express_test >= 3) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+
+    /* 1) Initialize an instance of the recursive R/W lock. */
+    result = H5TS__rw_lock_init(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_init");
+
+    /* 2) Setup the user data to be passed to each writer test thread. */
+    for (i = 0; i < MAX_NUM_THREADS; i++) {
+        memset(&udata[i], 0, sizeof(udata[i]));
+        udata[i].rw_lock                  = &rec_rw_lock;
+        udata[i].target_wr_lock_cycles    = lock_cycles;
+        udata[i].max_recursive_lock_depth = 10;
+    }
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    uint64_t start_time = H5_now_usec();
+#endif
+    /* 3) Create the writer threads, each with its own user data. */
+    for (i = 0; i < num_threads; i++)
+        if (H5TS_thread_create(&threads[i], tts_rw_lock_smoke_check_test_thread, &udata[i]) < 0)
+            TestErrPrintf("thread # %d did not start", i);
+
+    /* 4) Wait for all threads to complete. */
+    for (i = 0; i < num_threads; i++)
+        if (H5TS_thread_join(threads[i], NULL) < 0)
+            TestErrPrintf("thread %d failed to join", i);
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    uint64_t end_time  = H5_now_usec();
+    uint64_t elap_time = (unsigned long long)(end_time - start_time);
+    if (verbose)
+        fprintf(stdout, "elapsed usec: %" PRIu64 ", usec per lock_cycle = %" PRIu64 "\n", elap_time,
+                (elap_time / (uint64_t)lock_cycles));
+#endif
+
+    /* 5) Examine the user data from the threads, to determine the
+     *    total number of real and recursive read locks and unlock.
+     *
+     *    First, tally up the lock entries and exits from the test threads,
+     *    and store this data in the expected recursive R/W/ lock stats..
+     *    In passing, verify that each thread has done the expected number
+     *    of locks and unlocks.  Do these as asserts -- will run checks on
+     *    aggregate data shortly.
+     */
+
+    for (i = 0; i < num_threads; i++) {
+        assert(udata[i].target_rd_lock_cycles == udata[i].real_read_locks_granted);
+        assert(udata[i].target_rd_lock_cycles == udata[i].real_read_locks_released);
+        assert(udata[i].target_wr_lock_cycles == udata[i].real_write_locks_granted);
+        assert(udata[i].target_wr_lock_cycles == udata[i].real_write_locks_released);
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+        total_target_rd_lock_cycles += udata[i].target_rd_lock_cycles;
+        total_target_wr_lock_cycles += udata[i].target_wr_lock_cycles;
+
+        expected.read_locks_granted += udata[i].read_locks_granted;
+        expected.read_locks_released += udata[i].read_locks_released;
+        expected.real_read_locks_granted += udata[i].real_read_locks_granted;
+        expected.real_read_locks_released += udata[i].real_read_locks_released;
+        expected.write_locks_granted += udata[i].write_locks_granted;
+        expected.write_locks_released += udata[i].write_locks_released;
+        expected.real_write_locks_granted += udata[i].real_write_locks_granted;
+        expected.real_write_locks_released += udata[i].real_write_locks_released;
+#endif
+    }
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* Verify that the threads executed the expected number of read and write
+     * lock cycles.  If they didn't, some thread probably encountered an error
+     * and exited early.
+     */
+    if (total_target_rd_lock_cycles != expected.real_read_locks_granted ||
+        total_target_rd_lock_cycles != expected.real_read_locks_released ||
+        total_target_wr_lock_cycles != expected.real_write_locks_granted ||
+        total_target_wr_lock_cycles != expected.real_write_locks_released)
+        TestErrPrintf("Threads reported unexpected number of locks/unlocks.\n");
+
+    /* initialize remaining non-zero fields in the expected stats */
+    expected.max_write_locks                = 1;
+    expected.max_write_lock_recursion_depth = 10;
+    expected.max_write_locks_pending        = num_threads - 1;
+
+    /* 6) Obtain the stats from the recursive R/W lock, and compare
+     *     with the data gathered above.
+     */
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    /* turn off clang-format for readability */
+    /* clang-format off */
+    if (stats.read_locks_granted                 != expected.read_locks_granted ||
+            stats.read_locks_released            != expected.read_locks_released ||
+            stats.real_read_locks_granted        != expected.real_read_locks_granted ||
+            stats.real_read_locks_released       != expected.real_read_locks_released ||
+            stats.max_read_locks                 != expected.max_read_locks ||
+            stats.max_read_lock_recursion_depth  != expected.max_read_lock_recursion_depth ||
+            stats.read_locks_delayed             != expected.read_locks_delayed ||
+            stats.write_locks_granted            != expected.write_locks_granted ||
+            stats.write_locks_released           != expected.write_locks_released ||
+            stats.real_write_locks_granted       != expected.real_write_locks_granted ||
+            stats.real_write_locks_released      != expected.real_write_locks_released ||
+            stats.max_write_locks                != expected.max_write_locks ||
+            stats.max_write_lock_recursion_depth  > expected.max_write_lock_recursion_depth ||
+            stats.max_write_lock_recursion_depth  < 1 ||
+            stats.write_locks_delayed             < expected.write_locks_delayed ||
+            stats.max_write_locks_pending         > expected.max_write_locks_pending) {
+        TestErrPrintf("Unexpected recursive R/W lock stats");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+        H5TS__rw_lock_print_stats("Expected stats", &expected);
+    }
+    /* clang-format on */
+
+    if (verbose)
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+#endif
+
+    /* 7) Shut down the recursive R/W lock. */
+    result = H5TS__rw_lock_destroy(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_destroy");
+
+    /* discard the udata if it exists */
+    if (udata)
+        free(udata);
+} /* end tts_rec_rw_lock_smoke_check_3() */
+
+/*
+ **********************************************************************
+ * tts_rec_rw_lock_smoke_check_4 -- mixed mob
+ *
+ * Multi-thread test to check management of multiple readers and
+ * writers by the recursive R/W lock.  Test proceeds as follows:
+ *
+ *  1) Initialize an instance of the recursive R/W lock.
+ *
+ *  2) Setup the user data to be passed to each writer test thread.
+ *
+ *  3) Create the reader / writer threads, each with its own user data.
+ *     Activities of the reader / writer threads is discussed in the
+ *     header comment to tts_rw_lock_smoke_check_test_thread().
+ *
+ *  4) Wait for all threads to complete.
+ *
+ *  5) Examine the user data from the threads, to determine the
+ *     total number of real and recursive read & write locks and
+ *     unlock.
+ *
+ *  6) Obtain the stats from the recursive R/W lock, and compare
+ *     with the data gathered above.
+ *
+ *  7) Shut down the recursive R/W lock.
+ *
+ * The reader / writer threads obtain and drop the read or write
+ * locks a specified number of times.  Once a thread has a lock, it
+ * does random recursive locks / unlocks until drops the lock, and then
+ * repeats the process until the specified number of locks have
+ * been acquired and dropped.
+ *
+ **********************************************************************
+ */
+void
+tts_rec_rw_lock_smoke_check_4(void)
+{
+    herr_t                    result;
+    int                       i;
+    int                       express_test;
+    int                       num_threads = MAX_NUM_THREADS;
+    int                       lock_cycles = MAX_LOCK_CYCLES;
+    H5TS_thread_t             threads[MAX_NUM_THREADS];
+    rec_rw_lock_test_udata_t *udata = NULL;
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    hbool_t              verbose                     = FALSE;
+    int32_t              total_target_rd_lock_cycles = 0;
+    int32_t              total_target_wr_lock_cycles = 0;
+    H5TS_rw_lock_stats_t stats;
+    H5TS_rw_lock_stats_t expected;
+#endif
+    H5TS_rw_lock_t rec_rw_lock;
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* Reset expected stats fields to zero -- we will construct the expected
+     * stats from the thread udata after completion.
+     */
+    memset(&expected, 0, sizeof(expected));
+#endif
+
+    /* Allocate the udata */
+    udata = malloc(sizeof(*udata) * MAX_NUM_THREADS);
+    if (udata == NULL) {
+        TestErrPrintf("thread udata allocation failed.\n");
+
+        /* We can't do anything without the udata, so just return */
+        return;
+    }
+
+    /* Reduce # of threads and test cycles for higher levels of express testing */
+    express_test = GetTestExpress();
+    if (express_test >= 1) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+    if (express_test >= 2) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+    if (express_test >= 3) {
+        num_threads /= 2;
+        lock_cycles /= 10;
+    }
+
+    /* 1) Initialize an instance of the recursive R/W lock. */
+    result = H5TS__rw_lock_init(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_init");
+
+    /* 2) Setup the user data to be passed to each writer test thread. */
+    for (i = 0; i < MAX_NUM_THREADS; i++) {
+        memset(&udata[i], 0, sizeof(udata[i]));
+        udata[i].rw_lock                  = &rec_rw_lock;
+        udata[i].target_rd_lock_cycles    = lock_cycles;
+        udata[i].target_wr_lock_cycles    = lock_cycles;
+        udata[i].max_recursive_lock_depth = 10;
+    }
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    uint64_t start_time = H5_now_usec();
+#endif
+    /* 3) Create the reader threads, each with its own user data. */
+    for (i = 0; i < num_threads; i++)
+        if (H5TS_thread_create(&threads[i], tts_rw_lock_smoke_check_test_thread, &udata[i]) < 0)
+            TestErrPrintf("thread # %d did not start", i);
+
+    /* 4) Wait for all threads to complete. */
+    for (i = 0; i < num_threads; i++)
+        if (H5TS_thread_join(threads[i], NULL) < 0)
+            TestErrPrintf("thread %d failed to join", i);
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    uint64_t end_time  = H5_now_usec();
+    uint64_t elap_time = (unsigned long long)(end_time - start_time);
+    if (verbose)
+        fprintf(stdout, "elapsed usec: %" PRIu64 ", usec per lock_cycle = %" PRIu64 "\n", elap_time,
+                (elap_time / (uint64_t)lock_cycles));
+#endif
+
+    /* 5) Examine the user data from the threads, to determine the
+     *    total number of real and recursive read locks and unlock.
+     *
+     *    First, tally up the lock entries and exits from the test threads,
+     *    and store this data in the expected recursive R/W/ lock stats..
+     *    In passing, verify that each thread has done the expected number
+     *    of locks and unlocks.  Do these as asserts -- will run checks on
+     *    aggregate data shortly.
+     */
+
+    for (i = 0; i < num_threads; i++) {
+        assert(udata[i].target_rd_lock_cycles == udata[i].real_read_locks_granted);
+        assert(udata[i].target_rd_lock_cycles == udata[i].real_read_locks_released);
+        assert(udata[i].target_wr_lock_cycles == udata[i].real_write_locks_granted);
+        assert(udata[i].target_wr_lock_cycles == udata[i].real_write_locks_released);
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+        total_target_rd_lock_cycles += udata[i].target_rd_lock_cycles;
+        total_target_wr_lock_cycles += udata[i].target_wr_lock_cycles;
+
+        expected.read_locks_granted += udata[i].read_locks_granted;
+        expected.read_locks_released += udata[i].read_locks_released;
+        expected.real_read_locks_granted += udata[i].real_read_locks_granted;
+        expected.real_read_locks_released += udata[i].real_read_locks_released;
+        expected.write_locks_granted += udata[i].write_locks_granted;
+        expected.write_locks_released += udata[i].write_locks_released;
+        expected.real_write_locks_granted += udata[i].real_write_locks_granted;
+        expected.real_write_locks_released += udata[i].real_write_locks_released;
+#endif
+    }
+
+#if H5TS_ENABLE_REC_RW_LOCK_STATS
+    /* Verify that the threads executed the expected number of read and write
+     * lock cycles.  If they didn't, some thread probably encountered an error
+     * and exited early.
+     */
+    if (total_target_rd_lock_cycles != expected.real_read_locks_granted ||
+        total_target_rd_lock_cycles != expected.real_read_locks_released ||
+        total_target_wr_lock_cycles != expected.real_write_locks_granted ||
+        total_target_wr_lock_cycles != expected.real_write_locks_released)
+        TestErrPrintf("Threads reported unexpected number of locks/unlocks.\n");
+
+    /* initialize remaining non-zero fields in the expected stats */
+    expected.max_read_locks                 = num_threads;
+    expected.max_read_lock_recursion_depth  = 10;
+    expected.max_write_locks                = 1;
+    expected.max_write_lock_recursion_depth = 10;
+    expected.max_write_locks_pending        = num_threads - 1;
+
+    /* 6) Obtain the stats from the recursive R/W lock, and compare
+     *     with the data gathered above.
+     */
+    result = H5TS__rw_lock_get_stats(&rec_rw_lock, &stats);
+    CHECK_I(result, "H5TS__rw_lock_get_stats");
+
+    /* turn off clang-format for readability */
+    /* clang-format off */
+    if (stats.read_locks_granted                 != expected.read_locks_granted ||
+            stats.read_locks_released            != expected.read_locks_released ||
+            stats.real_read_locks_granted        != expected.real_read_locks_granted ||
+            stats.real_read_locks_released       != expected.real_read_locks_released ||
+            stats.max_read_locks                  > expected.max_read_locks ||
+            stats.max_read_locks                  < 1 ||
+            stats.max_read_lock_recursion_depth   > expected.max_read_lock_recursion_depth ||
+            stats.read_locks_delayed              < expected.read_locks_delayed ||
+            stats.write_locks_granted            != expected.write_locks_granted ||
+            stats.write_locks_released           != expected.write_locks_released ||
+            stats.real_write_locks_granted       != expected.real_write_locks_granted ||
+            stats.real_write_locks_released      != expected.real_write_locks_released ||
+            stats.max_write_locks                != expected.max_write_locks ||
+            stats.max_write_lock_recursion_depth  > expected.max_write_lock_recursion_depth ||
+            stats.max_write_lock_recursion_depth  < 1 ||
+            stats.write_locks_delayed             < expected.write_locks_delayed ||
+            stats.max_write_locks_pending         > expected.max_write_locks_pending) {
+        TestErrPrintf("Unexpected recursive R/W lock stats");
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+        H5TS__rw_lock_print_stats("Expected stats", &expected);
+    }
+    /* clang-format on */
+
+    if (verbose)
+        H5TS__rw_lock_print_stats("Actual stats", &stats);
+#endif
+
+    /* 7) Shut down the recursive R/W lock. */
+    result = H5TS__rw_lock_destroy(&rec_rw_lock);
+    CHECK_I(result, "H5TS__rw_lock_destroy");
+
+    /* discard the udata if it exists */
+    if (udata)
+        free(udata);
+} /* end tts_rec_rw_lock_smoke_check_4() */
+
+#endif /* H5_HAVE_WIN_THREADS */
+#endif /* H5_HAVE_THREADS */
diff --git a/tools/lib/h5diff.c b/tools/lib/h5diff.c
index bd8112f2c65..60dc5595aef 100644
--- a/tools/lib/h5diff.c
+++ b/tools/lib/h5diff.c
@@ -1746,7 +1746,7 @@ handle_worker_request(char *worker_tasks, int *n_busy_tasks, diff_opt_t *opts, h
     MPI_Status         status;
     int                task_idx  = 0;
     int                source    = 0;
-    herr_t             ret_value = H5DIFF_NO_ERR;
+    diff_err_t         ret_value = H5DIFF_NO_ERR;
 
     /* Must have at least one busy worker task */
     assert(*n_busy_tasks > 0);