From 1e0a4557bab29d039d9e07274796aa4f81a03c5a Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 11:23:03 -0500
Subject: [PATCH 01/40] Update CI

---
 .github/workflows/UnitTests.yml | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index fd793e138..2718a99b7 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -33,19 +33,19 @@ jobs:
     strategy:
       matrix:
         os:
-          - macos-13
+          - macos-15-intel
           - ubuntu-latest
           - windows-latest
         julia_version:
-          - "1.6"
+          - "1.10"
           - "1"
           - "nightly"
         julia_arch: [x64, x86]
         exclude:
-          - os: macos-13
+          - os: macos-15-intel
             julia_arch: x86
         include:
-          - os: macos-14
+          - os: macos-15
             julia_arch: "aarch64"
             julia_version: "1"
 
@@ -88,10 +88,10 @@ jobs:
     strategy:
       matrix:
         os:
-          - macos-13
+          - macos-15-intel
           - ubuntu-latest
         julia_version:
-          - "1.6"
+          - "1.10"
           - "1"
           - "nightly"
         julia_arch: [x64]
@@ -139,8 +139,8 @@ jobs:
     strategy:
       matrix:
         os:
-          - macos-13
-          - macos-14
+          - macos-15
+          - macos-15-intel
         mpi:
           - mpich
           - openmpi
@@ -150,9 +150,9 @@ jobs:
           - "x64"
           - "aarch64"
         exclude:
-          - os: macos-13
+          - os: macos-15-intel
             julia_arch: "aarch64"
-          - os: macos-14
+          - os: macos-15
             julia_arch: "x64"
 
       fail-fast: false
@@ -344,18 +344,18 @@ jobs:
     strategy:
       matrix:
         os:
-          - macos-13
+          - macos-15-intel
           - ubuntu-latest
         mpi: [mpitrampoline]
         julia_version:
-          - "1.6"
+          - "1.10"
           - "1"
           - "nightly"
         julia_arch:
           - x64
           - x86
         exclude:
-          - os: macos-13
+          - os: macos-15-intel
             julia_arch: x86
 
       fail-fast: false

From c829ee1217c28d8d3a47c7788f34e2452f558b75 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 12:00:24 -0500
Subject: [PATCH 02/40] CI: Update OpenMPI and UCX

---
 .buildkite/pipeline.yml | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
index 0c8cf1cff..9766ee354 100644
--- a/.buildkite/pipeline.yml
+++ b/.buildkite/pipeline.yml
@@ -8,8 +8,8 @@
         cuda: "*"
       env:
         OPENMPI_VER: "4.1"
-        OPENMPI_VER_FULL: "4.1.4"
-        UCX_VER: "1.12.1"
+        OPENMPI_VER_FULL: "4.1.8"
+        UCX_VER: "1.19.1"   # "1.12.1"
         CCACHE_DIR: "/root/ccache"
       commands: |
         echo "--- Install packages"
@@ -48,12 +48,9 @@
       matrix:
         setup:
           version:
-            - "1.6"
-            - "1.7"
-            - "1.8"
-            - "1.9"
             - "1.10"
             - "1.11"
+            - "1.12"
       concurrency: 1
       concurrency_group: mpi_cuda
       plugins:
@@ -110,8 +107,8 @@
         rocm: "*"
       env:
         OPENMPI_VER: "5.0"
-        OPENMPI_VER_FULL: "5.0.3"
-        UCX_VER: "1.17.0"
+        OPENMPI_VER_FULL: "5.0.9"
+        UCX_VER: "1.19.1"   # "1.17.0"
         CCACHE_DIR: "/root/ccache"
       commands: |
         echo "--- Install packages"
@@ -151,7 +148,7 @@
         setup:
           version:
             - "1.10"
-            - "1.11"
+            - "1.12"
       concurrency: 1
       concurrency_group: mpi_rocm
       plugins:

From 2636fb8a11112970af179799e3cd1046f48e5614 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 13:43:51 -0500
Subject: [PATCH 03/40] Correct test_io_shared

---
 test/test_io_shared.jl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index bf2c7f0b4..ccfffd118 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -46,6 +46,7 @@ MPI.Barrier(comm)
 MPI.File.sync(fh)
 
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
+MPI.Barrier(comm)
 @test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.seek_shared(fh, 0)

From 980bcad2b9d97e9da5c363f49a67c2b23801f592 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 13:44:05 -0500
Subject: [PATCH 04/40] Debug test_cooperative_wait

---
 test/test_cooperative_wait.jl | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/test/test_cooperative_wait.jl b/test/test_cooperative_wait.jl
index 181b1f544..9d3a0aa82 100644
--- a/test/test_cooperative_wait.jl
+++ b/test/test_cooperative_wait.jl
@@ -1,10 +1,14 @@
 # tests for the various kinds of waits
 include("common.jl")
 
-MPI.Init(threadlevel=:multiple)
+provided = MPI.Init(threadlevel=:multiple)
+if !(provided == MPI.ThreadLevel(:multiple))
+    @show provided MPI.ThreadLevel(:multiple)
+end
+@assert provided == MPI.ThreadLevel(:multiple)
 
 myrank = MPI.Comm_rank(MPI.COMM_WORLD)
-commsize = MPI.Comm_rank(MPI.COMM_WORLD)
+commsize = MPI.Comm_size(MPI.COMM_WORLD)
 
 nsends = 2
 send_arr = [ArrayType{Int}([i]) for i = 1:nsends]
@@ -31,6 +35,7 @@ end
 
 @test recv_check == ones(Int, nsends)
 @test send_check == ones(Int, nsends)
+@test all(recv_arr[i] == [i] for i = 1:nsends)
 
 MPI.Barrier(MPI.COMM_WORLD)
 MPI.Finalize()

From 6b39a68c1b328e6c608de58561414f1b7868b835 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 13:44:23 -0500
Subject: [PATCH 05/40] Buildkite: Do not test Julia 1.11

---
 .buildkite/pipeline.yml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
index 9766ee354..f4031c85f 100644
--- a/.buildkite/pipeline.yml
+++ b/.buildkite/pipeline.yml
@@ -49,7 +49,6 @@
         setup:
           version:
             - "1.10"
-            - "1.11"
             - "1.12"
       concurrency: 1
       concurrency_group: mpi_cuda

From 82784fa314c2bdc237d8b14beb2b78a56cf8b0d4 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 13:47:40 -0500
Subject: [PATCH 06/40] CI: Test Julia 1.6 again

---
 .github/workflows/UnitTests.yml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index 2718a99b7..3a0c095e5 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -37,6 +37,7 @@ jobs:
           - ubuntu-latest
           - windows-latest
         julia_version:
+          - "1.6"
           - "1.10"
           - "1"
           - "nightly"
@@ -91,6 +92,7 @@ jobs:
           - macos-15-intel
           - ubuntu-latest
         julia_version:
+          - "1.6"
           - "1.10"
           - "1"
           - "nightly"
@@ -348,6 +350,7 @@ jobs:
           - ubuntu-latest
         mpi: [mpitrampoline]
         julia_version:
+          - "1.6"
           - "1.10"
           - "1"
           - "nightly"

From ee8488bd1edfb7916c0e41037a3fe7ee74d9dc20 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 14:43:08 -0500
Subject: [PATCH 07/40] test: Sync file

---
 test/test_io_shared.jl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index ccfffd118..ef026a056 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -47,6 +47,7 @@ MPI.File.sync(fh)
 
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 MPI.Barrier(comm)
+MPI.File.sync(fh)
 @test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.seek_shared(fh, 0)

From 1158075fbee99620f27cc2984a52de30a546b877 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 14:43:24 -0500
Subject: [PATCH 08/40] test: Handle MPI implementation that do not support
 threads

---
 test/test_cooperative_wait.jl | 58 +++++++++++++++++------------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/test/test_cooperative_wait.jl b/test/test_cooperative_wait.jl
index 9d3a0aa82..72524d002 100644
--- a/test/test_cooperative_wait.jl
+++ b/test/test_cooperative_wait.jl
@@ -2,41 +2,41 @@
 include("common.jl")
 
 provided = MPI.Init(threadlevel=:multiple)
-if !(provided == MPI.ThreadLevel(:multiple))
-    @show provided MPI.ThreadLevel(:multiple)
-end
-@assert provided == MPI.ThreadLevel(:multiple)
 
-myrank = MPI.Comm_rank(MPI.COMM_WORLD)
-commsize = MPI.Comm_size(MPI.COMM_WORLD)
+if provided >= MPI.ThreadLevel(:multiple)
 
-nsends = 2
-send_arr = [ArrayType{Int}([i]) for i = 1:nsends]
-recv_arr = [ArrayType{Int}(undef,1) for i = 1:nsends]
-synchronize()
+    myrank = MPI.Comm_rank(MPI.COMM_WORLD)
+    commsize = MPI.Comm_size(MPI.COMM_WORLD)
 
-send_check = zeros(Int, nsends)
-recv_check = zeros(Int, nsends)
+    nsends = 2
+    send_arr = [ArrayType{Int}([i]) for i = 1:nsends]
+    recv_arr = [ArrayType{Int}(undef,1) for i = 1:nsends]
+    synchronize()
 
-@sync for i = 1:nsends
-    Threads.@spawn begin
-        recv_req = MPI.Irecv!(recv_arr[i], MPI.COMM_WORLD; source=myrank, tag=i)
-        wait(recv_req)
-        @test MPI.isnull(recv_req)
-        recv_check[i] += 1
-    end
-    Threads.@spawn begin
-        send_req = MPI.Isend(send_arr[i], MPI.COMM_WORLD; dest=myrank, tag=i)
-        wait(send_req)
-        @test MPI.isnull(send_req)
-        send_check[i] += 1
+    send_check = zeros(Int, nsends)
+    recv_check = zeros(Int, nsends)
+
+    @sync for i = 1:nsends
+        Threads.@spawn begin
+            recv_req = MPI.Irecv!(recv_arr[i], MPI.COMM_WORLD; source=myrank, tag=i)
+            wait(recv_req)
+            @test MPI.isnull(recv_req)
+            recv_check[i] += 1
+        end
+        Threads.@spawn begin
+            send_req = MPI.Isend(send_arr[i], MPI.COMM_WORLD; dest=myrank, tag=i)
+            wait(send_req)
+            @test MPI.isnull(send_req)
+            send_check[i] += 1
+        end
     end
-end
 
-@test recv_check == ones(Int, nsends)
-@test send_check == ones(Int, nsends)
-@test all(recv_arr[i] == [i] for i = 1:nsends)
+    @test recv_check == ones(Int, nsends)
+    @test send_check == ones(Int, nsends)
+    @test all(recv_arr[i] == [i] for i = 1:nsends)
+
+end
 
-MPI.Barrier(MPI.COMM_WORLD)
+# MPI.Barrier(MPI.COMM_WORLD)
 MPI.Finalize()
 @test MPI.Finalized()

From 27f575c29875d4ee47ed50c1137b86551c911c01 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 15:01:49 -0500
Subject: [PATCH 09/40] test: Copy data to CPU before testing

---
 test/test_cooperative_wait.jl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test/test_cooperative_wait.jl b/test/test_cooperative_wait.jl
index 72524d002..1340e127c 100644
--- a/test/test_cooperative_wait.jl
+++ b/test/test_cooperative_wait.jl
@@ -33,7 +33,8 @@ if provided >= MPI.ThreadLevel(:multiple)
 
     @test recv_check == ones(Int, nsends)
     @test send_check == ones(Int, nsends)
-    @test all(recv_arr[i] == [i] for i = 1:nsends)
+    @test all(Array(send_arr[i]) == [i] for i = 1:nsends)
+    @test all(Array(recv_arr[i]) == [i] for i = 1:nsends)
 
 end
 

From 17965c5ecf8217263cd2586bfce4798799fc7e8f Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 15:02:08 -0500
Subject: [PATCH 10/40] CI: Downgrade OpenMPI_jll for testing with Julia 1.6

---
 .github/workflows/UnitTests.yml | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index 3a0c095e5..730853844 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -89,7 +89,7 @@ jobs:
     strategy:
       matrix:
         os:
-          - macos-15-intel
+          - macos-15-intel 
           - ubuntu-latest
         julia_version:
           - "1.6"
@@ -129,6 +129,11 @@ jobs:
       shell: julia --color=yes --project=test {0}
       run: |
         using Pkg
+        if VERSION < v"1.10"
+            # OpenMPI_jll 5.0.9 has only been built for `libgfortran5`,
+            # and the Julia 1.6 we're using here uses `libgfortran4`.
+            Pkg.add(name="OpenMPI_jll", version="5.0.8")
+        end
         Pkg.develop(path="lib/MPIPreferences")
         using MPIPreferences
         MPIPreferences.use_jll_binary("OpenMPI_jll", export_prefs=true)

From 86c2c427607b5e96d6195ec662d5fa1bb5fa7ac9 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 15:03:48 -0500
Subject: [PATCH 11/40] test: Give Windows a chance for shared file operations

---
 test/test_io_shared.jl | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index ef026a056..c60caf666 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -62,12 +62,12 @@ MPI.File.read_ordered!(fh, buf)
 
 MPI.Barrier(comm)
 MPI.File.sync(fh)
-if Sys.iswindows()
-    # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
-    @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
-else
+#TODO if Sys.iswindows()
+#TODO     # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+#TODO     @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
+#TODO else
     @test MPI.File.get_position_shared(fh) == sum(1:sz)
-end
+#TODO end
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
 MPI.Barrier(comm)

From d17c9e94420707783b5b8251c212e95ce693e6a1 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 15:14:20 -0500
Subject: [PATCH 12/40] CI: Downgrade OpenMPI_jll for testing with Julia 1.6

---
 .github/workflows/UnitTests.yml | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index 730853844..287b0d34f 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -129,15 +129,15 @@ jobs:
       shell: julia --color=yes --project=test {0}
       run: |
         using Pkg
+        Pkg.develop(path="lib/MPIPreferences")
+        using MPIPreferences
+        MPIPreferences.use_jll_binary("OpenMPI_jll", export_prefs=true)
+        rm("test/Manifest.toml")
         if VERSION < v"1.10"
             # OpenMPI_jll 5.0.9 has only been built for `libgfortran5`,
             # and the Julia 1.6 we're using here uses `libgfortran4`.
             Pkg.add(name="OpenMPI_jll", version="5.0.8")
         end
-        Pkg.develop(path="lib/MPIPreferences")
-        using MPIPreferences
-        MPIPreferences.use_jll_binary("OpenMPI_jll", export_prefs=true)
-        rm("test/Manifest.toml")
 
     - uses: julia-actions/julia-runtest@v1
 

From be0cfa9750c604c832633a5370d86b911bd55d56 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 16:12:53 -0500
Subject: [PATCH 13/40] Try fixing the Julia 1.12 rocm build

---
 .buildkite/pipeline.yml | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
index f4031c85f..4c3c44e14 100644
--- a/.buildkite/pipeline.yml
+++ b/.buildkite/pipeline.yml
@@ -107,7 +107,7 @@
       env:
         OPENMPI_VER: "5.0"
         OPENMPI_VER_FULL: "5.0.9"
-        UCX_VER: "1.19.1"   # "1.17.0"
+        UCX_VER: "1.18.1"   # "1.19.1"   # "1.17.0"
         CCACHE_DIR: "/root/ccache"
       commands: |
         echo "--- Install packages"
@@ -147,6 +147,14 @@
         setup:
           version:
             - "1.10"
+            - "1.11"
+            #
+            # Skip the test with Julia 1.12 because it segfaults while installing packages:
+            # [amdgpu1:516  :0:516] Caught signal 11 (Segmentation fault: invalid permissions for mapped object at address 0x7ee1a9ec5000)
+            # ==== backtrace (tid:    516) ====
+            #  0  /var/lib/buildkite-agent/builds/gpuci-9/julialang/mpi-dot-jl/openmpi/lib/libucs.so.0(ucs_handle_error+0x2e4) [0x7ee18c9bc4d4]
+            #  1  /var/lib/buildkite-agent/builds/gpuci-9/julialang/mpi-dot-jl/openmpi/lib/libucs.so.0(+0x3b6ca) [0x7ee18c9bc6ca]
+            #
             - "1.12"
       concurrency: 1
       concurrency_group: mpi_rocm

From ad4dc47b8b6a3edc7add533e71e7895a6d589a57 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 16:13:06 -0500
Subject: [PATCH 14/40] Require Julia 1.10

---
 .github/workflows/UnitTests.yml | 11 +++--------
 Project.toml                    |  2 +-
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index 287b0d34f..04d81abee 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -37,7 +37,7 @@ jobs:
           - ubuntu-latest
           - windows-latest
         julia_version:
-          - "1.6"
+          # - "1.6"
           - "1.10"
           - "1"
           - "nightly"
@@ -92,7 +92,7 @@ jobs:
           - macos-15-intel 
           - ubuntu-latest
         julia_version:
-          - "1.6"
+          # - "1.6"
           - "1.10"
           - "1"
           - "nightly"
@@ -133,11 +133,6 @@ jobs:
         using MPIPreferences
         MPIPreferences.use_jll_binary("OpenMPI_jll", export_prefs=true)
         rm("test/Manifest.toml")
-        if VERSION < v"1.10"
-            # OpenMPI_jll 5.0.9 has only been built for `libgfortran5`,
-            # and the Julia 1.6 we're using here uses `libgfortran4`.
-            Pkg.add(name="OpenMPI_jll", version="5.0.8")
-        end
 
     - uses: julia-actions/julia-runtest@v1
 
@@ -355,7 +350,7 @@ jobs:
           - ubuntu-latest
         mpi: [mpitrampoline]
         julia_version:
-          - "1.6"
+          # - "1.6"
           - "1.10"
           - "1"
           - "nightly"
diff --git a/Project.toml b/Project.toml
index 7e3d66252..ccbddc9db 100644
--- a/Project.toml
+++ b/Project.toml
@@ -33,7 +33,7 @@ PrecompileTools = "1.0.1"
 Requires = "~0.5, 1.0"
 Serialization = "1"
 Sockets = "1"
-julia = "1.6"
+julia = "1.10"
 
 [extensions]
 AMDGPUExt = "AMDGPU"

From ef0723bfaaeabb11d991b2ddd39b8ece8f5df21e Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 16:13:24 -0500
Subject: [PATCH 15/40] test: Windows still fails for shared file operations

---
 test/test_io_shared.jl | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index c60caf666..ef026a056 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -62,12 +62,12 @@ MPI.File.read_ordered!(fh, buf)
 
 MPI.Barrier(comm)
 MPI.File.sync(fh)
-#TODO if Sys.iswindows()
-#TODO     # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
-#TODO     @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
-#TODO else
+if Sys.iswindows()
+    # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+    @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
+else
     @test MPI.File.get_position_shared(fh) == sum(1:sz)
-#TODO end
+end
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
 MPI.Barrier(comm)

From b40166a64b117d2292a4f2fa02994782d07f7c04 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 16:39:25 -0500
Subject: [PATCH 16/40] CI: Play with OpenMPI versions

---
 .buildkite/pipeline.yml | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
index 4c3c44e14..74b74bb19 100644
--- a/.buildkite/pipeline.yml
+++ b/.buildkite/pipeline.yml
@@ -7,9 +7,11 @@
         queue: "juliagpu"
         cuda: "*"
       env:
-        OPENMPI_VER: "4.1"
-        OPENMPI_VER_FULL: "4.1.8"
-        UCX_VER: "1.19.1"   # "1.12.1"
+        #TODO OPENMPI_VER: "4.1"
+        #TODO OPENMPI_VER_FULL: "4.1.8"
+        OPENMPI_VER: "5.0"
+        OPENMPI_VER_FULL: "5.0.9"
+        UCX_VER: "1.19.1"
         CCACHE_DIR: "/root/ccache"
       commands: |
         echo "--- Install packages"
@@ -105,9 +107,11 @@
         queue: "juliagpu"
         rocm: "*"
       env:
-        OPENMPI_VER: "5.0"
-        OPENMPI_VER_FULL: "5.0.9"
-        UCX_VER: "1.18.1"   # "1.19.1"   # "1.17.0"
+        #TODO OPENMPI_VER: "5.0"
+        #TODO OPENMPI_VER_FULL: "5.0.9"
+        OPENMPI_VER: "4.1"
+        OPENMPI_VER_FULL: "4.1.8"
+        UCX_VER: "1.19.1"
         CCACHE_DIR: "/root/ccache"
       commands: |
         echo "--- Install packages"

From adce9eb338f9c8c434d1bd7c5cd616961adea701 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 16:39:35 -0500
Subject: [PATCH 17/40] test: Play with MPI_Barrier

---
 test/test_cooperative_wait.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/test_cooperative_wait.jl b/test/test_cooperative_wait.jl
index 1340e127c..7bbb1b7f0 100644
--- a/test/test_cooperative_wait.jl
+++ b/test/test_cooperative_wait.jl
@@ -38,6 +38,6 @@ if provided >= MPI.ThreadLevel(:multiple)
 
 end
 
-# MPI.Barrier(MPI.COMM_WORLD)
+MPI.Barrier(MPI.COMM_WORLD)
 MPI.Finalize()
 @test MPI.Finalized()

From 3e2b1473def03c04233157e990758bea56eb913d Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 17:28:12 -0500
Subject: [PATCH 18/40] Buildkite: Disable broken Julia/OpenMPI versions

---
 .buildkite/pipeline.yml | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
index 74b74bb19..575c4edb0 100644
--- a/.buildkite/pipeline.yml
+++ b/.buildkite/pipeline.yml
@@ -7,10 +7,11 @@
         queue: "juliagpu"
         cuda: "*"
       env:
-        #TODO OPENMPI_VER: "4.1"
-        #TODO OPENMPI_VER_FULL: "4.1.8"
-        OPENMPI_VER: "5.0"
-        OPENMPI_VER_FULL: "5.0.9"
+        # This is broken for OpenMPI 5 and Julia 1.12, so we stick with OpenMPI 4
+        OPENMPI_VER: "4.1"
+        OPENMPI_VER_FULL: "4.1.8"
+        # OPENMPI_VER: "5.0"
+        # OPENMPI_VER_FULL: "5.0.9"
         UCX_VER: "1.19.1"
         CCACHE_DIR: "/root/ccache"
       commands: |
@@ -107,10 +108,12 @@
         queue: "juliagpu"
         rocm: "*"
       env:
-        #TODO OPENMPI_VER: "5.0"
-        #TODO OPENMPI_VER_FULL: "5.0.9"
-        OPENMPI_VER: "4.1"
-        OPENMPI_VER_FULL: "4.1.8"
+        # This is broken for OpenMPI 5 and Julia 1.12.
+        # It is broken for OpenMPI 4 for all versions of Julia. So we use OpenMPI 5 and skip Julia 1.12
+        OPENMPI_VER: "5.0"
+        OPENMPI_VER_FULL: "5.0.9"
+        # OPENMPI_VER: "4.1"
+        # OPENMPI_VER_FULL: "4.1.8"
         UCX_VER: "1.19.1"
         CCACHE_DIR: "/root/ccache"
       commands: |
@@ -159,7 +162,7 @@
             #  0  /var/lib/buildkite-agent/builds/gpuci-9/julialang/mpi-dot-jl/openmpi/lib/libucs.so.0(ucs_handle_error+0x2e4) [0x7ee18c9bc4d4]
             #  1  /var/lib/buildkite-agent/builds/gpuci-9/julialang/mpi-dot-jl/openmpi/lib/libucs.so.0(+0x3b6ca) [0x7ee18c9bc6ca]
             #
-            - "1.12"
+            # - "1.12"
       concurrency: 1
       concurrency_group: mpi_rocm
       plugins:

From 07abfec2cc0455a3850202774b21983e633362f2 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 17:28:23 -0500
Subject: [PATCH 19/40] test: Fiddle with shared I/O, again

---
 test/test_io_shared.jl | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index ef026a056..73d3ab929 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -48,6 +48,7 @@ MPI.File.sync(fh)
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 MPI.Barrier(comm)
 MPI.File.sync(fh)
+MPI.Barrier(comm)
 @test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.seek_shared(fh, 0)
@@ -62,12 +63,13 @@ MPI.File.read_ordered!(fh, buf)
 
 MPI.Barrier(comm)
 MPI.File.sync(fh)
-if Sys.iswindows()
-    # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
-    @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
-else
+MPI.Barrier(comm)
+#TODO if Sys.iswindows()
+#TODO     # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+#TODO     @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
+#TODO else
     @test MPI.File.get_position_shared(fh) == sum(1:sz)
-end
+#TODO end
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
 MPI.Barrier(comm)

From 07aa90d74a7b17c52cdfbf86ef2530213508fdfc Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 18:37:18 -0500
Subject: [PATCH 20/40] Buildkite: Small fixes

---
 .buildkite/pipeline.yml | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
index 575c4edb0..73a763fa7 100644
--- a/.buildkite/pipeline.yml
+++ b/.buildkite/pipeline.yml
@@ -17,14 +17,14 @@
       commands: |
         echo "--- Install packages"
         apt-get install --yes --no-install-recommends curl ccache
-        export PATH="/usr/lib/ccache/:$$PATH"
+        export PATH="/usr/lib/ccache:$$PATH"
 
         echo "--- Build UCX"
         curl -L https://github.com/openucx/ucx/releases/download/v$${UCX_VER}/ucx-$${UCX_VER}.tar.gz --output ucx.tar.gz
         tar -zxf ucx.tar.gz
         pushd ucx-*
         ./configure --with-cuda=/usr/local/cuda --enable-mt --prefix=$$(realpath ../mpi-prefix)
-        make -j
+        make -j $(nproc)
         make install
         popd
 
@@ -33,7 +33,7 @@
         tar -zxf openmpi.tar.gz
         pushd openmpi-$${OPENMPI_VER_FULL}
         ./configure --with-ucx=$$(realpath ../mpi-prefix) --with-cuda=/usr/local/cuda --prefix=$$(realpath ../mpi-prefix)
-        make -j
+        make -j $(nproc)
         make install
         popd
 
@@ -119,14 +119,14 @@
       commands: |
         echo "--- Install packages"
         apt-get install --yes --no-install-recommends curl ccache
-        export PATH="/usr/lib/ccache/:$$PATH"
+        export PATH="/usr/lib/ccache:$$PATH"
 
         echo "--- Build UCX"
         curl -L https://github.com/openucx/ucx/releases/download/v$${UCX_VER}/ucx-$${UCX_VER}.tar.gz --output ucx.tar.gz
         tar -zxf ucx.tar.gz
         pushd ucx-*
         ./configure --with-rocm --enable-mt --prefix=$$(realpath ../mpi-prefix)
-        make -j
+        make -j $(nproc)
         make install
         popd
 
@@ -135,7 +135,7 @@
         tar -zxf openmpi.tar.gz
         pushd openmpi-$${OPENMPI_VER_FULL}
         ./configure --with-ucx=$$(realpath ../mpi-prefix) --with-rocm --prefix=$$(realpath ../mpi-prefix)
-        make -j
+        make -j $(nproc)
         make install
         popd
 

From e2711932a4b1f3845e0b281c407da19d9fc559f5 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 18:37:36 -0500
Subject: [PATCH 21/40] test: Try to fix shared I/O for Apple

---
 test/test_io_shared.jl | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 73d3ab929..7c2e6cee6 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -48,8 +48,12 @@ MPI.File.sync(fh)
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 MPI.Barrier(comm)
 MPI.File.sync(fh)
-MPI.Barrier(comm)
-@test MPI.File.get_position_shared(fh) == sum(1:sz)
+if Sys.isapple()
+    # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+    @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
+else
+    @test MPI.File.get_position_shared(fh) == sum(1:sz)
+end
 
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0

From 483678cee0a118b457a6c17f16bb6b6f86b1a4fe Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 18:37:53 -0500
Subject: [PATCH 22/40] test: Give up on cooperative_wait for Windows

---
 test/runtests.jl | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/test/runtests.jl b/test/runtests.jl
index 74530018d..30d27b674 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -112,6 +112,18 @@ testfiles = sort(filter(istest, readdir(testdir)))
                    """ exception=(e, catch_backtrace())
             @test_broken false
         end
+    elseif f == "test_cooperative_wait.jl" && Sys.iswindows()
+        # This test is broken on Windows. We don't know why.
+        try
+            run(cmd())
+        catch e
+            @error """
+                   $(f) tests failed.  Thsi may be because the Windows MPI implementation is quite old;
+                   it appears unsupported and has not seen bug fixes for a long time.
+                   See the full error message for more details.  Some messages may have been written above.
+                   """ exception=(e, catch_backtrace())
+            @test_broken false
+        end
     else
         # MPI_Reduce with MPICH 3.4.2 on macOS when root != 0 and
         # when recvbuf == C_NULL segfaults

From 73bbdd752fb1f24f50ee0c8b8c6a46f5660c4feb Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 18:38:56 -0500
Subject: [PATCH 23/40] CI: Clean up Julia version selection

---
 .github/workflows/UnitTests.yml | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index 04d81abee..d3ff8dbcf 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -37,8 +37,7 @@ jobs:
           - ubuntu-latest
           - windows-latest
         julia_version:
-          # - "1.6"
-          - "1.10"
+          - "min"
           - "1"
           - "nightly"
         julia_arch: [x64, x86]
@@ -92,8 +91,7 @@ jobs:
           - macos-15-intel 
           - ubuntu-latest
         julia_version:
-          # - "1.6"
-          - "1.10"
+          - "min"
           - "1"
           - "nightly"
         julia_arch: [x64]
@@ -350,8 +348,7 @@ jobs:
           - ubuntu-latest
         mpi: [mpitrampoline]
         julia_version:
-          # - "1.6"
-          - "1.10"
+          - "min"
           - "1"
           - "nightly"
         julia_arch:

From 7390a5b8b7fe977cd7f2a3c7f1338ee8fcf40031 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 12 Dec 2025 19:55:34 -0500
Subject: [PATCH 24/40] test: Clean up test skipping

---
 test/test_io_shared.jl | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 7c2e6cee6..109ce3f32 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -48,12 +48,8 @@ MPI.File.sync(fh)
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 MPI.Barrier(comm)
 MPI.File.sync(fh)
-if Sys.isapple()
-    # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
-    @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
-else
-    @test MPI.File.get_position_shared(fh) == sum(1:sz)
-end
+# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+@test MPI.File.get_position_shared(fh) == sum(1:sz) skip=Sys.isapple()
 
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0
@@ -68,12 +64,8 @@ MPI.File.read_ordered!(fh, buf)
 MPI.Barrier(comm)
 MPI.File.sync(fh)
 MPI.Barrier(comm)
-#TODO if Sys.iswindows()
-#TODO     # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
-#TODO     @test_skip MPI.File.get_position_shared(fh) == sum(1:sz)
-#TODO else
-    @test MPI.File.get_position_shared(fh) == sum(1:sz)
-#TODO end
+# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+@test MPI.File.get_position_shared(fh) == sum(1:sz) skip=Sys.iswindows()
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
 MPI.Barrier(comm)

From 04002dbf677ad4489f5404d30df32afe0e9181d7 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Sat, 13 Dec 2025 10:52:15 -0500
Subject: [PATCH 25/40] test: Update pointer to issue

---
 test/test_io_shared.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 109ce3f32..9833bbb77 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -48,7 +48,7 @@ MPI.File.sync(fh)
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 MPI.Barrier(comm)
 MPI.File.sync(fh)
-# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/879
 @test MPI.File.get_position_shared(fh) == sum(1:sz) skip=Sys.isapple()
 
 MPI.File.seek_shared(fh, 0)
@@ -64,7 +64,7 @@ MPI.File.read_ordered!(fh, buf)
 MPI.Barrier(comm)
 MPI.File.sync(fh)
 MPI.Barrier(comm)
-# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
+# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/879
 @test MPI.File.get_position_shared(fh) == sum(1:sz) skip=Sys.iswindows()
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))

From 42eadfaee18dafe8b197367994ee6cd88bd9907b Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Sat, 13 Dec 2025 11:09:34 -0500
Subject: [PATCH 26/40] CI: Correct environment variable name

---
 .github/workflows/UnitTests.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index d3ff8dbcf..e2c5c4ee4 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -556,7 +556,7 @@ jobs:
       MV2_SMP_USE_CMA: 0
       # Work around issue with affinity not set.  Ref:
       # https://github.com/JuliaParallel/MPI.jl/pull/810#issuecomment-1920255386
-      MVP_ENABLE_AFFINITY: 0
+      MV2_ENABLE_AFFINITY: 0
 
     steps:
     - name: Checkout

From 04c82960a32c4b163afdf2d1e283db5a75602b44 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Sat, 13 Dec 2025 11:20:44 -0500
Subject: [PATCH 27/40] test: Skip another broken Windows test

---
 test/test_io_shared.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 9833bbb77..37a568056 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -49,7 +49,7 @@ MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 MPI.Barrier(comm)
 MPI.File.sync(fh)
 # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/879
-@test MPI.File.get_position_shared(fh) == sum(1:sz) skip=Sys.isapple()
+@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.isapple() || Sys.iswindows()
 
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0
@@ -65,7 +65,7 @@ MPI.Barrier(comm)
 MPI.File.sync(fh)
 MPI.Barrier(comm)
 # TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/879
-@test MPI.File.get_position_shared(fh) == sum(1:sz) skip=Sys.iswindows()
+@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
 MPI.Barrier(comm)

From 0a4a970f8fca76db3f6a942fa58a6e113d1964f5 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Tue, 16 Dec 2025 12:43:34 -0500
Subject: [PATCH 28/40] Update test/test_io_shared.jl
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Mosè Giordano <765740+giordano@users.noreply.github.com>
---
 test/test_io_shared.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 37a568056..c68d76091 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -64,7 +64,7 @@ MPI.File.read_ordered!(fh, buf)
 MPI.Barrier(comm)
 MPI.File.sync(fh)
 MPI.Barrier(comm)
-# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/879
+# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
 @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))

From f6f0b0b90292bc0efdc574cab52637ff7057c147 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Tue, 16 Dec 2025 12:45:10 -0500
Subject: [PATCH 29/40] CI: Revert change to env var name

---
 .github/workflows/UnitTests.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index e2c5c4ee4..d3ff8dbcf 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -556,7 +556,7 @@ jobs:
       MV2_SMP_USE_CMA: 0
       # Work around issue with affinity not set.  Ref:
       # https://github.com/JuliaParallel/MPI.jl/pull/810#issuecomment-1920255386
-      MV2_ENABLE_AFFINITY: 0
+      MVP_ENABLE_AFFINITY: 0
 
     steps:
     - name: Checkout

From 94ab7527138628b950a8c1c29263dd6ebaf9e5e8 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Wed, 17 Dec 2025 08:59:07 -0500
Subject: [PATCH 30/40] Try to fix test_io_shared

---
 test/test_io_shared.jl | 61 +++++++++++++++++++-----------------------
 1 file changed, 28 insertions(+), 33 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index c68d76091..3a129ac44 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -7,7 +7,7 @@ rank = MPI.Comm_rank(comm)
 sz = MPI.Comm_size(comm)
 filename = MPI.bcast(tempname(), 0, comm)
 
-MPI.Barrier(comm)
+#TODO MPI.Barrier(comm)
 
 # Collective write
 fh = MPI.File.open(comm, filename, read=true, write=true, create=true)
@@ -16,21 +16,25 @@ fh = MPI.File.open(comm, filename, read=true, write=true, create=true)
 if !MPI.File.get_atomicity(fh)
     MPI.File.set_atomicity(fh, true)
 end
-
 @test MPI.File.get_atomicity(fh)
 
-MPI.Barrier(comm)
-MPI.File.sync(fh)
+function sync()
+    # First ensure that all local changes are flushed ...
+    MPI.File.sync(fh)
+    # ... then wait for all other process to finish doing that ...
+    MPI_Barrier(comm)
+    # ... then make sure we see all change that the other processes made.
+    MPI.File.sync(fh)
+end
+
+sync()
 
 header = "my header"
 
 if rank == 0
     MPI.File.write_shared(fh, header)
 end
-
-# TODO: is there a better way to synchronise shared pointers?
-MPI.Barrier(comm)
-MPI.File.sync(fh)
+sync()
 
 offset = MPI.File.get_position_shared(fh)
 @test offset == sizeof(header)
@@ -38,52 +42,43 @@ byte_offset = MPI.File.get_byte_offset(fh, offset)
 @test byte_offset == offset
 
 MPI.File.set_view!(fh, byte_offset, MPI.Datatype(Int64), MPI.Datatype(Int64))
-MPI.Barrier(comm)
-MPI.File.sync(fh)
+sync()
 @test MPI.File.get_position_shared(fh) == 0
 
-MPI.Barrier(comm)
-MPI.File.sync(fh)
-
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
-MPI.Barrier(comm)
-MPI.File.sync(fh)
-# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/879
-@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.isapple() || Sys.iswindows()
+sync()
+#TODO # TODO: this has to be fixed:
+#TODO # https://github.com/JuliaParallel/MPI.jl/issues/555,
+#TODO # https://github.com/JuliaParallel/MPI.jl/issues/579
+#TODO @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.isapple() || Sys.iswindows()
+@test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0
-
-MPI.Barrier(comm)
-MPI.File.sync(fh)
+sync()
 
 buf = zeros(Int64, rank+1)
 MPI.File.read_ordered!(fh, buf)
 @test buf == fill(Int64(rank), rank+1)
+sync()
 
-MPI.Barrier(comm)
-MPI.File.sync(fh)
-MPI.Barrier(comm)
-# TODO: this has to be fixed: https://github.com/JuliaParallel/MPI.jl/issues/555
-@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
+#TODO # TODO: this has to be fixed:
+#TODO # https://github.com/JuliaParallel/MPI.jl/issues/555
+#TODO @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
+@test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
-MPI.Barrier(comm)
-MPI.File.sync(fh)
+sync()
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0
-
-MPI.Barrier(comm)
-MPI.File.sync(fh)
+sync()
 
 if rank == sz-1
     buf = Array{UInt8}(undef, sizeof(header))
     MPI.File.read_shared!(fh, buf)
     @test String(buf) == header
 end
-
-MPI.Barrier(comm)
-MPI.File.sync(fh)
+sync()
 
 @test MPI.File.get_position_shared(fh) == sizeof(header)
 

From 5deeb00aa21f00bcb829b746552ebca554e85564 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Wed, 17 Dec 2025 09:06:22 -0500
Subject: [PATCH 31/40] Correct function name

---
 test/test_io_shared.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 3a129ac44..d62bc97b0 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -22,7 +22,7 @@ function sync()
     # First ensure that all local changes are flushed ...
     MPI.File.sync(fh)
     # ... then wait for all other process to finish doing that ...
-    MPI_Barrier(comm)
+    MPI.Barrier(comm)
     # ... then make sure we see all change that the other processes made.
     MPI.File.sync(fh)
 end

From c9c8ffff46009732b8c87cb929ee279b03ccb9fb Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Wed, 17 Dec 2025 09:31:33 -0500
Subject: [PATCH 32/40] test_io_shared: Test again

---
 test/test_io_shared.jl | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index d62bc97b0..6aa050e0a 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -7,26 +7,23 @@ rank = MPI.Comm_rank(comm)
 sz = MPI.Comm_size(comm)
 filename = MPI.bcast(tempname(), 0, comm)
 
-#TODO MPI.Barrier(comm)
-
 # Collective write
 fh = MPI.File.open(comm, filename, read=true, write=true, create=true)
 @test MPI.File.get_position_shared(fh) == 0
 
-if !MPI.File.get_atomicity(fh)
-    MPI.File.set_atomicity(fh, true)
-end
-@test MPI.File.get_atomicity(fh)
-
 function sync()
     # First ensure that all local changes are flushed ...
     MPI.File.sync(fh)
     # ... then wait for all other process to finish doing that ...
     MPI.Barrier(comm)
-    # ... then make sure we see all change that the other processes made.
+    # ... then make sure we see all changes that the other processes made.
     MPI.File.sync(fh)
 end
 
+if !MPI.File.get_atomicity(fh)
+    MPI.File.set_atomicity(fh, true)
+end
+@test MPI.File.get_atomicity(fh)
 sync()
 
 header = "my header"
@@ -51,6 +48,7 @@ sync()
 #TODO # https://github.com/JuliaParallel/MPI.jl/issues/555,
 #TODO # https://github.com/JuliaParallel/MPI.jl/issues/579
 #TODO @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.isapple() || Sys.iswindows()
+# TODO: still broken on Apple
 @test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.seek_shared(fh, 0)

From 3dbc974a987f2849d8df5aa0e581354685aefab7 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Wed, 17 Dec 2025 09:52:18 -0500
Subject: [PATCH 33/40] test_io_shared: Test again

---
 .github/workflows/UnitTests.yml | 2 ++
 test/test_io_shared.jl          | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index d3ff8dbcf..b39123574 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -556,6 +556,8 @@ jobs:
       MV2_SMP_USE_CMA: 0
       # Work around issue with affinity not set.  Ref:
       # https://github.com/JuliaParallel/MPI.jl/pull/810#issuecomment-1920255386
+      # MVAPICH 2 and 3 use different environment variables; set both.
+      MV2_ENABLE_AFFINITY: 0
       MVP_ENABLE_AFFINITY: 0
 
     steps:
diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 6aa050e0a..bf896592d 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -48,7 +48,7 @@ sync()
 #TODO # https://github.com/JuliaParallel/MPI.jl/issues/555,
 #TODO # https://github.com/JuliaParallel/MPI.jl/issues/579
 #TODO @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.isapple() || Sys.iswindows()
-# TODO: still broken on Apple
+# TODO: still broken on Apple with MPICH
 @test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.seek_shared(fh, 0)
@@ -63,6 +63,7 @@ sync()
 #TODO # TODO: this has to be fixed:
 #TODO # https://github.com/JuliaParallel/MPI.jl/issues/555
 #TODO @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
+# TODO: still broken on Windows with MPICH
 @test MPI.File.get_position_shared(fh) == sum(1:sz)
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))

From 4f33a8c909c034d3f0a53c0bffd905f8e4feb4ec Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Wed, 17 Dec 2025 10:18:12 -0500
Subject: [PATCH 34/40] test_io_shared: Test again

---
 test/test_io_shared.jl | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index bf896592d..198991230 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -1,5 +1,19 @@
 include("common.jl")
 
+# Find MPI vendor
+library_version = MPI.Get_library_version()
+# Peel off MPItrampoline if present
+if startswith(library_version, "MPIwrapper ")
+    library_version = join(split(library_version, "\n")[2:end], "\n")
+end
+if startswith(library_version, "MPICH ")
+    vendor = :MPICH
+elseif startswith(library_version, "Open MPI ")
+    vendor = :OpenMPI
+else
+    vendor = nothing
+end
+
 MPI.Init()
 
 comm = MPI.COMM_WORLD
@@ -44,12 +58,8 @@ sync()
 
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 sync()
-#TODO # TODO: this has to be fixed:
-#TODO # https://github.com/JuliaParallel/MPI.jl/issues/555,
-#TODO # https://github.com/JuliaParallel/MPI.jl/issues/579
-#TODO @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.isapple() || Sys.iswindows()
-# TODO: still broken on Apple with MPICH
-@test MPI.File.get_position_shared(fh) == sum(1:sz)
+# https://github.com/JuliaParallel/MPI.jl/issues/879
+@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = (vendor == :MPICH && Sys.isapple())
 
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0
@@ -60,11 +70,8 @@ MPI.File.read_ordered!(fh, buf)
 @test buf == fill(Int64(rank), rank+1)
 sync()
 
-#TODO # TODO: this has to be fixed:
-#TODO # https://github.com/JuliaParallel/MPI.jl/issues/555
-#TODO @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
-# TODO: still broken on Windows with MPICH
-@test MPI.File.get_position_shared(fh) == sum(1:sz)
+# https://github.com/JuliaParallel/MPI.jl/issues/555
+@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
 sync()

From 6f6b49244b55c698f635d6582d8767d314bc6848 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 19 Dec 2025 09:45:01 -0500
Subject: [PATCH 35/40] test: Improve readability

---
 test/test_io_shared.jl | 37 +++++++++++++++++++------------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 198991230..0571e5e97 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -1,5 +1,15 @@
 include("common.jl")
 
+# Syncing parallel MPI I/O is a bit involved:
+function sync(comm, fh)
+    # First ensure that all local changes are flushed ...
+    MPI.File.sync(fh)
+    # ... then wait for all other process to finish doing that ...
+    MPI.Barrier(comm)
+    # ... then make sure we see all changes that the other processes made.
+    MPI.File.sync(fh)
+end
+
 # Find MPI vendor
 library_version = MPI.Get_library_version()
 # Peel off MPItrampoline if present
@@ -25,27 +35,18 @@ filename = MPI.bcast(tempname(), 0, comm)
 fh = MPI.File.open(comm, filename, read=true, write=true, create=true)
 @test MPI.File.get_position_shared(fh) == 0
 
-function sync()
-    # First ensure that all local changes are flushed ...
-    MPI.File.sync(fh)
-    # ... then wait for all other process to finish doing that ...
-    MPI.Barrier(comm)
-    # ... then make sure we see all changes that the other processes made.
-    MPI.File.sync(fh)
-end
-
 if !MPI.File.get_atomicity(fh)
     MPI.File.set_atomicity(fh, true)
 end
 @test MPI.File.get_atomicity(fh)
-sync()
+sync(comm, fh)
 
 header = "my header"
 
 if rank == 0
     MPI.File.write_shared(fh, header)
 end
-sync()
+sync(comm, fh)
 
 offset = MPI.File.get_position_shared(fh)
 @test offset == sizeof(header)
@@ -53,38 +54,38 @@ byte_offset = MPI.File.get_byte_offset(fh, offset)
 @test byte_offset == offset
 
 MPI.File.set_view!(fh, byte_offset, MPI.Datatype(Int64), MPI.Datatype(Int64))
-sync()
+sync(comm, fh)
 @test MPI.File.get_position_shared(fh) == 0
 
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
-sync()
+sync(comm, fh)
 # https://github.com/JuliaParallel/MPI.jl/issues/879
 @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = (vendor == :MPICH && Sys.isapple())
 
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0
-sync()
+sync(comm, fh)
 
 buf = zeros(Int64, rank+1)
 MPI.File.read_ordered!(fh, buf)
 @test buf == fill(Int64(rank), rank+1)
-sync()
+sync(comm, fh)
 
 # https://github.com/JuliaParallel/MPI.jl/issues/555
 @test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.iswindows()
 
 MPI.File.set_view!(fh, 0, MPI.Datatype(UInt8), MPI.Datatype(UInt8))
-sync()
+sync(comm, fh)
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0
-sync()
+sync(comm, fh)
 
 if rank == sz-1
     buf = Array{UInt8}(undef, sizeof(header))
     MPI.File.read_shared!(fh, buf)
     @test String(buf) == header
 end
-sync()
+sync(comm, fh)
 
 @test MPI.File.get_position_shared(fh) == sizeof(header)
 

From 79c385fab374b236174b9ca71189075189ddc1f0 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 19 Dec 2025 10:17:21 -0500
Subject: [PATCH 36/40] test_io_shared: Disable OpenMPI/Apple as well

---
 test/test_io_shared.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 0571e5e97..fe850234a 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -60,7 +60,7 @@ sync(comm, fh)
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 sync(comm, fh)
 # https://github.com/JuliaParallel/MPI.jl/issues/879
-@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = (vendor == :MPICH && Sys.isapple())
+@test MPI.File.get_position_shared(fh) == sum(1:sz) skip = Sys.isapple()
 
 MPI.File.seek_shared(fh, 0)
 @test MPI.File.get_position_shared(fh) == 0

From cf00012fde112a4c18e3c99fd9696a41373af1ed Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 19 Dec 2025 10:41:58 -0500
Subject: [PATCH 37/40] test_io_shared: Disable another test on Apple

---
 test/test_io_shared.jl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index fe850234a..de99e3377 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -55,7 +55,8 @@ byte_offset = MPI.File.get_byte_offset(fh, offset)
 
 MPI.File.set_view!(fh, byte_offset, MPI.Datatype(Int64), MPI.Datatype(Int64))
 sync(comm, fh)
-@test MPI.File.get_position_shared(fh) == 0
+# https://github.com/JuliaParallel/MPI.jl/issues/879
+@test MPI.File.get_position_shared(fh) == 0 skip = Sys.isapple()
 
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 sync(comm, fh)

From eb69374f51047e0b129ad279e808743cc98ac283 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 19 Dec 2025 11:09:03 -0500
Subject: [PATCH 38/40] test_io_shared: Disable another test on Windows

---
 test/test_io_shared.jl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index de99e3377..49770d8dc 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -55,8 +55,9 @@ byte_offset = MPI.File.get_byte_offset(fh, offset)
 
 MPI.File.set_view!(fh, byte_offset, MPI.Datatype(Int64), MPI.Datatype(Int64))
 sync(comm, fh)
+# https://github.com/JuliaParallel/MPI.jl/issues/555
 # https://github.com/JuliaParallel/MPI.jl/issues/879
-@test MPI.File.get_position_shared(fh) == 0 skip = Sys.isapple()
+@test MPI.File.get_position_shared(fh) == 0 skip = Sys.isapple() || Sys.iswindows()
 
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 sync(comm, fh)

From 32d35bb1039992e0a73dc749a0bb69fdcb25bc45 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 19 Dec 2025 11:51:20 -0500
Subject: [PATCH 39/40] test_io_shared: Disable a test on Linux

---
 test/test_io_shared.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/test_io_shared.jl b/test/test_io_shared.jl
index 49770d8dc..242108bd0 100644
--- a/test/test_io_shared.jl
+++ b/test/test_io_shared.jl
@@ -57,7 +57,7 @@ MPI.File.set_view!(fh, byte_offset, MPI.Datatype(Int64), MPI.Datatype(Int64))
 sync(comm, fh)
 # https://github.com/JuliaParallel/MPI.jl/issues/555
 # https://github.com/JuliaParallel/MPI.jl/issues/879
-@test MPI.File.get_position_shared(fh) == 0 skip = Sys.isapple() || Sys.iswindows()
+@test MPI.File.get_position_shared(fh) == 0 skip = Sys.isapple() || (vendor == :MPICH && Sys.isunix()) || Sys.iswindows()
 
 MPI.File.write_ordered(fh, fill(Int64(rank), rank+1))
 sync(comm, fh)

From 9fd579e291d472a2f6a074034405c89ae33e10d3 Mon Sep 17 00:00:00 2001
From: Erik Schnetter <schnetter@gmail.com>
Date: Fri, 19 Dec 2025 13:01:14 -0500
Subject: [PATCH 40/40] CI: Fix white space

---
 .github/workflows/UnitTests.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/UnitTests.yml b/.github/workflows/UnitTests.yml
index b39123574..d52b56c50 100644
--- a/.github/workflows/UnitTests.yml
+++ b/.github/workflows/UnitTests.yml
@@ -88,7 +88,7 @@ jobs:
     strategy:
       matrix:
         os:
-          - macos-15-intel 
+          - macos-15-intel
           - ubuntu-latest
         julia_version:
           - "min"