From b8bd28c662b8286bbd1edaaa80653827496e4bda Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Thu, 4 Sep 2025 18:55:07 -0700
Subject: [PATCH 01/24] Initial port of read_stl_mesh_shared and
 quest::signed_distance functionality so it uses Umpire shared memory
 allocators.

---
 .../quest/interface/internal/QuestHelpers.cpp | 243 ++++++++----------
 .../quest/interface/internal/QuestHelpers.hpp | 137 +---------
 src/axom/quest/interface/signed_distance.cpp  |  53 ++--
 .../tests/quest_signed_distance_interface.cpp |  19 +-
 4 files changed, 155 insertions(+), 297 deletions(-)

diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index 4049749e55..ce50416f75 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -23,6 +23,11 @@
   #endif
 #endif
 
+#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
+  #include "umpire/Umpire.hpp"
+  #define AXOM_USE_UMPIRE_SHARED_MEMORY
+#endif
+
 #include <limits>
 
 namespace axom
@@ -31,40 +36,84 @@ namespace quest
 {
 namespace internal
 {
-/// MPI Helper/Wrapper Methods
-
-#ifdef AXOM_USE_MPI
+/// Mesh I/O methods
 
-/*
- * Deallocates the specified MPI window object.
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+/*!
+ * \brief Allocates a shared memory buffer for the mesh that is shared among
+ *  all the ranks within the same compute node.
+ *
+ * \param [in] allocatorID A valid Umpire allocator id that can allocate shared memory.
+ * \param [in] mesh_metada tuple with the number of nodes/faces on the mesh
+ * \param [out] x pointer into the buffer where the x--coordinates are stored.
+ * \param [out] y pointer into the buffer where the y--coordinates are stored.
+ * \param [out] z pointer into the buffer where the z--coordinates are stored.
+ * \param [out] conn pointer into the buffer consisting the cell-connectivity.
+ * \param [out] mesh_buffer raw buffer consisting of all the mesh data.
+ *
+ * \return bytesize the number of bytes in the raw buffer.
+ *
+ * \pre allocatorID is a valid shared memory allocator.
+ * \pre mesh_metadata != nullptr
+ * \pre x == nullptr
+ * \pre y == nullptr
+ * \pre z == nullptr
+ * \pre conn == nullptr
+ * \pre mesh_buffer == nullptr
+ *
+ * \post x != nullptr
+ * \post y != nullptr
+ * \post z != nullptr
+ * \post coon != nullptr
+ * \post mesh_buffer != nullptr
  */
-void mpi_win_free(MPI_Win* window)
+static size_t allocate_shared_buffer(int allocatorID,
+                              const axom::IndexType mesh_metadata[2],
+                              double*& x,
+                              double*& y,
+                              double*& z,
+                              axom::IndexType*& conn,
+                              unsigned char*& mesh_buffer)
 {
-  if(*window != MPI_WIN_NULL)
-  {
-    MPI_Win_free(window);
-  }
-}
+  // Allocate the buffer.
+  const axom::IndexType nnodes = mesh_metadata[0];
+  const axom::IndexType nfaces = mesh_metadata[1];
+  const size_t bytesize = nnodes * 3 * sizeof(double) + nfaces * 3 * sizeof(axom::IndexType);
+  mesh_buffer = allocate<unsigned char>(bytesize, allocatorID);
 
-/*
- * Deallocates the specified MPI communicator object.
- */
-void mpi_comm_free(MPI_Comm* comm)
-{
-  if(*comm != MPI_COMM_NULL)
-  {
-    MPI_Comm_free(comm);
-  }
+  // calculate offset to the coordinates & cell connectivity in the buffer
+  int baseOffset = nnodes * sizeof(double);
+  int x_offset = 0;
+  int y_offset = baseOffset;
+  int z_offset = y_offset + baseOffset;
+  int conn_offset = z_offset + baseOffset;
+
+  x = reinterpret_cast<double*>(&mesh_buffer[x_offset]);
+  y = reinterpret_cast<double*>(&mesh_buffer[y_offset]);
+  z = reinterpret_cast<double*>(&mesh_buffer[z_offset]);
+  conn = reinterpret_cast<axom::IndexType*>(&mesh_buffer[conn_offset]);
+
+  return (bytesize);
 }
 
-/*
- * Reads the mesh on rank 0 and exchanges the mesh metadata, i.e., the
- * number of nodes and faces with all other ranks.
+/*!
+ * \brief Reads the mesh on rank 0 and exchanges the mesh metadata, i.e., the
+ *  number of nodes and faces with all other ranks.
+ *
+ * \param [in] global_rank_id MPI rank w.r.t. the global communicator
+ * \param [in] global_comm handle to the global communicator
+ * \param [in,out] reader the corresponding STL reader
+ * \param [out] mesh_metadata an array consisting of the mesh metadata.
+ *
+ * \note This method calls read() on the reader on rank 0.
+ *
+ * \pre global_comm != MPI_COMM_NULL
+ * \pre mesh_metadata != nullptr
  */
-int read_and_exchange_mesh_metadata(int global_rank_id,
-                                    MPI_Comm global_comm,
-                                    quest::STLReader& reader,
-                                    axom::IndexType mesh_metadata[2])
+static int read_and_exchange_mesh_metadata(int global_rank_id,
+                                           MPI_Comm global_comm,
+                                           quest::STLReader& reader,
+                                           axom::IndexType mesh_metadata[2])
 {
   constexpr int NUM_NODES = 0;
   constexpr int NUM_FACES = 1;
@@ -94,108 +143,18 @@ int read_and_exchange_mesh_metadata(int global_rank_id,
   return rc;
 }
 
-#endif /* AXOM_USE_MPI */
-
-#ifdef AXOM_USE_MPI3
-/*
- * Creates inter-node and intra-node communicators from the given global
- * MPI communicator handle.
- */
-void create_communicators(MPI_Comm global_comm,
-                          MPI_Comm& intra_node_comm,
-                          MPI_Comm& inter_node_comm,
-                          int& global_rank_id,
-                          int& local_rank_id,
-                          int& intercom_rank_id)
-{
-  // Sanity checks
-  SLIC_ASSERT(global_comm != MPI_COMM_NULL);
-  SLIC_ASSERT(intra_node_comm == MPI_COMM_NULL);
-  SLIC_ASSERT(inter_node_comm == MPI_COMM_NULL);
-
-  constexpr int IGNORE_KEY = 0;
-
-  // STEP 0: get global rank, used to order ranks in the inter-node comm.
-  MPI_Comm_rank(global_comm, &global_rank_id);
-
-  // STEP 1: create the intra-node communicator
-  MPI_Comm_split_type(global_comm, MPI_COMM_TYPE_SHARED, IGNORE_KEY, MPI_INFO_NULL, &intra_node_comm);
-  MPI_Comm_rank(intra_node_comm, &local_rank_id);
-  SLIC_ASSERT(local_rank_id >= 0);
-
-  // STEP 2: create inter-node communicator
-  const int color = (local_rank_id == 0) ? 1 : MPI_UNDEFINED;
-  MPI_Comm_split(global_comm, color, global_rank_id, &inter_node_comm);
-
-  if(color == 1)
-  {
-    MPI_Comm_rank(inter_node_comm, &intercom_rank_id);
-  }
-
-  SLIC_ASSERT(intra_node_comm != MPI_COMM_NULL);
-}
-#endif
-
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
-/*
- * Allocates a shared memory buffer for the mesh that is shared among
- * all the ranks within the same compute node.
- */
-MPI_Aint allocate_shared_buffer(int local_rank_id,
-                                MPI_Comm intra_node_comm,
-                                const axom::IndexType mesh_metadata[2],
-                                double*& x,
-                                double*& y,
-                                double*& z,
-                                axom::IndexType*& conn,
-                                unsigned char*& mesh_buffer,
-                                MPI_Win& shared_window)
-{
-  constexpr int ROOT_RANK = 0;
-
-  const int nnodes = mesh_metadata[0];
-  const int nfaces = mesh_metadata[1];
-
-  int disp = sizeof(unsigned char);
-  MPI_Aint bytesize = nnodes * 3 * sizeof(double) + nfaces * 3 * sizeof(axom::IndexType);
-  MPI_Aint window_size = (local_rank_id != ROOT_RANK) ? 0 : bytesize;
-
-  MPI_Win_allocate_shared(window_size, disp, MPI_INFO_NULL, intra_node_comm, &mesh_buffer, &shared_window);
-  MPI_Win_shared_query(shared_window, ROOT_RANK, &bytesize, &disp, &mesh_buffer);
-
-  // calculate offset to the coordinates & cell connectivity in the buffer
-  int baseOffset = nnodes * sizeof(double);
-  int x_offset = 0;
-  int y_offset = baseOffset;
-  int z_offset = y_offset + baseOffset;
-  int conn_offset = z_offset + baseOffset;
-
-  x = reinterpret_cast<double*>(&mesh_buffer[x_offset]);
-  y = reinterpret_cast<double*>(&mesh_buffer[y_offset]);
-  z = reinterpret_cast<double*>(&mesh_buffer[z_offset]);
-  conn = reinterpret_cast<axom::IndexType*>(&mesh_buffer[conn_offset]);
-
-  return (bytesize);
-}
-#endif
-
-/// Mesh I/O methods
-
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
 /*
  * Reads in the surface mesh from the specified file into a shared
  * memory buffer that is attached to the given MPI shared window.
  */
 int read_stl_mesh_shared(const std::string& file,
                          MPI_Comm global_comm,
+                         int allocatorID,
                          unsigned char*& mesh_buffer,
-                         mint::Mesh*& m,
-                         MPI_Comm& intra_node_comm,
-                         MPI_Win& shared_window)
+                         mint::Mesh*& m)
 {
   SLIC_ASSERT(global_comm != MPI_COMM_NULL);
-  SLIC_ASSERT(intra_node_comm == MPI_COMM_NULL);
-  SLIC_ASSERT(shared_window == MPI_WIN_NULL);
+  SLIC_ASSERT(allocatorID != INVALID_ALLOCATOR_ID);
 
   // NOTE: STL meshes are always 3D mesh consisting of triangles.
   using TriangleMesh = mint::UnstructuredMesh<mint::SINGLE_SHAPE>;
@@ -213,17 +172,23 @@ int read_stl_mesh_shared(const std::string& file,
     return READ_FAILED;
   }
 
-  // STEP 1: create intra-node and inter-node MPI communicators
+  // STEP 1: Get the communicator from the Umpire allocator.
   int global_rank_id = -1;
-  int local_rank_id = -1;
   int intercom_rank_id = -1;
+  MPI_Comm_rank(global_comm, &global_rank_id);
   MPI_Comm inter_node_comm = MPI_COMM_NULL;
-  create_communicators(global_comm,
-                       intra_node_comm,
-                       inter_node_comm,
-                       global_rank_id,
-                       local_rank_id,
-                       intercom_rank_id);
+  umpire::ResourceManager& rm = umpire::ResourceManager::getInstance();
+  if(rm.isAllocator(allocatorID))
+  {
+    umpire::Allocator allocator = rm.getAllocator(allocatorID);
+    inter_node_comm = umpire::get_communicator_for_allocator(allocator, global_comm);
+    MPI_Comm_rank(inter_node_comm, &intercom_rank_id);
+std::cout << "Rank " << global_rank_id << ": intercom_rank_id=" << intercom_rank_id << std::endl;
+  }
+  else
+  {
+    SLIC_ERROR(axom::fmt::format("An invalid allocatorID {} was provided.", allocatorID));
+  }
 
   // STEP 2: Exchange mesh metadata
   constexpr int NUM_NODES = 0;
@@ -243,15 +208,13 @@ int read_stl_mesh_shared(const std::string& file,
   double* y = nullptr;
   double* z = nullptr;
   axom::IndexType* conn = nullptr;
-  MPI_Aint numBytes = allocate_shared_buffer(local_rank_id,
-                                             intra_node_comm,
-                                             mesh_metadata,
-                                             x,
-                                             y,
-                                             z,
-                                             conn,
-                                             mesh_buffer,
-                                             shared_window);
+  const size_t numBytes = allocate_shared_buffer(allocatorID,
+                                                 mesh_metadata,
+                                                 x,
+                                                 y,
+                                                 z,
+                                                 conn,
+                                                 mesh_buffer);
   SLIC_ASSERT(x != nullptr);
   SLIC_ASSERT(y != nullptr);
   SLIC_ASSERT(z != nullptr);
@@ -267,16 +230,14 @@ int read_stl_mesh_shared(const std::string& file,
     reader.getMesh(static_cast<TriangleMesh*>(m));
   }
 
-  // STEP 5: inter-node communication
+  // STEP 5: inter-node communication (broadcast mesh_buffer to shared_memory on other nodes)
   if(intercom_rank_id >= 0)
   {
     MPI_Bcast(mesh_buffer, numBytes, MPI_UNSIGNED_CHAR, 0, inter_node_comm);
   }
 
-  // STEP 6 free communicators
+  // NOTE: Communicators are associated with Umpire allocators and Umpire will free them.
 
-  MPI_Barrier(global_comm);
-  mpi_comm_free(&inter_node_comm);
   return READ_SUCCESS;
 }
 #endif
diff --git a/src/axom/quest/interface/internal/QuestHelpers.hpp b/src/axom/quest/interface/internal/QuestHelpers.hpp
index 8fe5da0760..d350e875c1 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.hpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.hpp
@@ -60,137 +60,10 @@ class ScopedLogLevelChanger
   slic::message::Level m_previousLevel {slic::message::Level::Debug};
 };
 
-/// \name MPI Helper/Wrapper Methods
-/// @{
-#ifdef AXOM_USE_MPI
-
-/*!
- * \brief Deallocates the specified MPI window object.
- * \param [in] window handle to the MPI window.
- * \note All buffers attached to the window are also deallocated.
- */
-void mpi_win_free(MPI_Win* window);
-
-/*!
- * \brief Deallocates the specified MPI communicator object.
- * \param [in] comm handle to the MPI communicator object.
- */
-void mpi_comm_free(MPI_Comm* comm);
-
-/*!
- * \brief Reads the mesh on rank 0 and exchanges the mesh metadata, i.e., the
- *  number of nodes and faces with all other ranks.
- *
- * \param [in] global_rank_id MPI rank w.r.t. the global communicator
- * \param [in] global_comm handle to the global communicator
- * \param [in,out] reader the corresponding STL reader
- * \param [out] mesh_metadata an array consisting of the mesh metadata.
- *
- * \note This method calls read() on the reader on rank 0.
- *
- * \pre global_comm != MPI_COMM_NULL
- * \pre mesh_metadata != nullptr
- */
-int read_and_exchange_mesh_metadata(int global_rank_id,
-                                    MPI_Comm global_comm,
-                                    quest::STLReader& reader,
-                                    axom::IndexType mesh_metadata[2]);
-
-#endif /* AXOM_USE_MPI */
-
-#ifdef AXOM_USE_MPI3
-/*!
- * \brief Creates inter-node and intra-node communicators from the given global
- *  MPI communicator handle.
- *
- *  The intra-node communicator groups the ranks within the same compute node.
- *  Consequently, all ranks have a global rank ID, w.r.t. the global
- *  communicator, and a corresponding local rank ID, w.r.t. the intra-node
- *  communicator. The global rank ID can span and is unique across multiple
- *  compute nodes, while the local rank ID, is only uniquely defined within the
- *  same compute node and is generally different from the global rank ID.
- *
- *  In contrast, the inter-node communicator groups only a subset of the ranks
- *  defined by the global communicator. Specifically, ranks that have a
- *  local rank ID of zero are included in the inter-node commuinicator and
- *  have a corresponding inter-comm rank ID, w.r.t., the inter-node
- *  communicator. For all other ranks, that are not included in the inter-node
- *  communicator, the inter-comm rank ID is set to "-1".
- *
- * \param [in]  global_comm handle to the global MPI communicator.
- * \param [out] intra_node_comm handle to the intra-node communicator object.
- * \param [out] inter_node_comm handle to the inter-node communicator object.
- * \param [out] global_rank_id rank ID w.r.t. the global communicator
- * \param [out] local_rank_id rank ID within the a compute node
- * \param [out] intercom_rank_id rank ID w.r.t. the inter-node communicator
-
- * \note The caller must call `MPI_Comm_free` on the corresponding communicator
- *  handles, namely, `intra_node_comm` and `inter_node_comm` which are created
- *  by this routine.
- *
- * \pre global_comm != MPI_COMM_NULL
- * \pre intra_node_comm == MPI_COMM_NULL
- * \pre inter_node_comm == MPI_COMM_NULL
- * \post intra_node_comm != MPI_COMM_NULL
- * \post inter_node_comm != MPI_COMM_NULL
- */
-void create_communicators(MPI_Comm global_comm,
-                          MPI_Comm& intra_node_comm,
-                          MPI_Comm& inter_node_comm,
-                          int& global_rank_id,
-                          int& local_rank_id,
-                          int& intercom_rank_id);
-#endif
-
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
-/*!
- * \brief Allocates a shared memory buffer for the mesh that is shared among
- *  all the ranks within the same compute node.
- *
- * \param [in] intra_node_comm intra-node communicator within a node.
- * \param [in] mesh_metada tuple with the number of nodes/faces on the mesh
- * \param [out] x pointer into the buffer where the x--coordinates are stored.
- * \param [out] y pointer into the buffer where the y--coordinates are stored.
- * \param [out] z pointer into the buffer where the z--coordinates are stored.
- * \param [out] conn pointer into the buffer consisting the cell-connectivity.
- * \param [out] mesh_buffer raw buffer consisting of all the mesh data.
- * \param [out] shared_window MPI window to which the shared buffer is attached.
- *
- * \return bytesize the number of bytes in the raw buffer.
- *
- * \pre intra_node_comm != MPI_COMM_NULL
- * \pre mesh_metadata != nullptr
- * \pre x == nullptr
- * \pre y == nullptr
- * \pre z == nullptr
- * \pre conn == nullptr
- * \pre mesh_buffer == nullptr
- * \pre shared_window == MPI_WIN_NULL
- *
- * \post x != nullptr
- * \post y != nullptr
- * \post z != nullptr
- * \post coon != nullptr
- * \post mesh_buffer != nullptr
- * \post shared_window != MPI_WIN_NULL
- */
-MPI_Aint allocate_shared_buffer(int local_rank_id,
-                                MPI_Comm intra_node_comm,
-                                const axom::IndexType mesh_metadata[2],
-                                double*& x,
-                                double*& y,
-                                double*& z,
-                                axom::IndexType*& conn,
-                                unsigned char*& mesh_buffer,
-                                MPI_Win& shared_window);
-#endif
-
-/// @}
-
 /// \name Mesh I/O methods
 /// @{
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
+#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
 
 /*!
  * \brief Reads in the surface mesh from the specified file into a shared
@@ -198,10 +71,9 @@ MPI_Aint allocate_shared_buffer(int local_rank_id,
  *
  * \param [in] file the file consisting of the surface mesh
  * \param [in] global_comm handle to the global MPI communicator
+ * \param [in] allocatorID An UMPIRE allocator ID that can allocate shared memory.
  * \param [out] mesh_buffer pointer to the raw mesh buffer
  * \param [out] m pointer to the mesh object
- * \param [out] intra_node_comm handle to the shared MPI communicator.
- * \param [out] shared_window handle to the MPI shared window.
  *
  * \return status set to READ_SUCCESS, or READ_FAILED on error.
  *
@@ -224,10 +96,9 @@ MPI_Aint allocate_shared_buffer(int local_rank_id,
  */
 int read_stl_mesh_shared(const std::string& file,
                          MPI_Comm global_comm,
+                         int allocatorID,
                          unsigned char*& mesh_buffer,
-                         mint::Mesh*& m,
-                         MPI_Comm& intra_node_comm,
-                         MPI_Win& shared_window);
+                         mint::Mesh*& m);
 #endif
 
 /*!
diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index ee7a18038c..3bacfe6224 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -13,10 +13,21 @@
 
 #include "axom/slic/interface/slic.hpp"
 
+#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE)
+  #include "umpire/Umpire.hpp"
+  #if defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY)
+    #include "umpire/strategy/NamedAllocationStrategy.hpp"
+    #include "umpire/util/MemoryResourceTraits.hpp"
+    #define AXOM_USE_UMPIRE_SHARED_MEMORY
+  #endif
+#endif
+
 #ifdef AXOM_USE_MPI
   #include <mpi.h>
 #endif
 
+#include <string>
+
 namespace axom
 {
 namespace quest
@@ -60,7 +71,7 @@ static struct parameters_t
 
   bool verbose;              /*!< logger verbosity */
   bool is_closed_surface;    /*!< indicates if the input is a closed surface */
-  bool use_shared_memory;    /*!< use MPI-3 shared memory for the surface mesh */
+  bool use_shared_memory;    /*!< use Umpire shared memory for the surface mesh */
   bool compute_sign;         /*!< indicates if sign should be computed */
   int allocator_id;          /*!< the allocator ID to create BVH with (-1 for default) */
   SignedDistExec exec_space; /*!< indicates the execution space to run in */
@@ -93,10 +104,13 @@ static bool s_must_delete_mesh = false;
 static bool s_must_finalize_logger = false;
 static bool s_logger_is_initialized = false;
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+static int s_allocator_id = INVALID_ALLOCATOR_ID;
 static unsigned char* s_shared_mesh_buffer = nullptr;
-MPI_Comm s_intra_node_comm = MPI_COMM_NULL;
-MPI_Win s_window = MPI_WIN_NULL;
+#else
+static std::string s_shared_memory_requirements(
+                      "Shared memory requires MPI and an Umpire library built with "
+                      "UMPIRE_ENABLE_IPC_SHARED_MEMORY set to ON");
 #endif
 
 }  // end anonymous namespace
@@ -122,16 +136,26 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
   // STEP 0: read the STL mesh
   int rc = INIT_FAILED;
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+  if(s_allocator_id == INVALID_ALLOCATOR_ID)
+  {
+    // Make a shared memory allocator and get its id.
+    auto& rm = umpire::ResourceManager::getInstance();
+    auto traits{umpire::get_default_resource_traits("SHARED")};
+    traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
+    auto node_allocator{rm.makeResource("SHARED::node_allocator", traits)};
+    auto signed_distance_allocator{
+      rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>("signed_distance_allocator", node_allocator)};
+    s_allocator_id = signed_distance_allocator.getId();
+  }
 
   if(Parameters.use_shared_memory)
   {
     rc = internal::read_stl_mesh_shared(file,
                                         comm,
+                                        s_allocator_id,
                                         s_shared_mesh_buffer,
-                                        s_surface_mesh,
-                                        s_intra_node_comm,
-                                        s_window);
+                                        s_surface_mesh);
   }
   else
   {
@@ -141,8 +165,7 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
 #else
 
   SLIC_WARNING_IF(Parameters.use_shared_memory,
-                  "Shared memory requires MPI3 and building Axom with "
-                  "AXOM_USE_MPI3 set to ON");
+                  s_shared_memory_requirements_message);
 
   rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
 #endif
@@ -313,9 +336,9 @@ void signed_distance_use_shared_memory(bool status)
 
   Parameters.use_shared_memory = status;
 
-#ifndef AXOM_USE_MPI3
+#if !defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
   SLIC_WARNING_IF(Parameters.use_shared_memory,
-                  "Enabling shared memory requires MPI-3. Option is ignored!");
+                  s_shared_memory_requirements + " Option is ignored!");
 #endif
 }
 
@@ -499,10 +522,8 @@ void signed_distance_finalize()
   SLIC_ASSERT(!signed_distance_initialized());
   internal::logger_finalize(s_must_finalize_logger);
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
-  internal::mpi_comm_free(&s_intra_node_comm);
-  internal::mpi_win_free(&s_window);
-  s_shared_mesh_buffer = nullptr;
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+  deallocate(s_shared_mesh_buffer);
 #endif
 }
 
diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index e9edffaed5..ebfc1acdfa 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -46,8 +46,11 @@ using UnstructuredMesh = mint::UnstructuredMesh<mint::SINGLE_SHAPE>;
 //------------------------------------------------------------------------------
 namespace
 {
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
-constexpr bool USE_MPI3_SHARED_MEMORY = true;
+#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
+#define AXOM_USE_UMPIRE_SHARED_MEMORY
+constexpr bool USE_SHARED_MEMORY = true;
+#else
+constexpr bool USE_SHARED_MEMORY = false;
 #endif
 
 /*!
@@ -410,17 +413,17 @@ TEST(quest_signed_distance_interface, analytic_plane)
 {
   check_analytic_plane();
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
-  check_analytic_plane(USE_MPI3_SHARED_MEMORY);
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+  check_analytic_plane(USE_SHARED_MEMORY);
 #endif
 }
 
 //------------------------------------------------------------------------------
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_MPI3)
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
 TEST(quest_signed_distance_interface, call_twice_using_shared_memory)
 {
-  check_analytic_plane(USE_MPI3_SHARED_MEMORY);
-  check_analytic_plane(USE_MPI3_SHARED_MEMORY);
+  check_analytic_plane(USE_SHARED_MEMORY);
+  check_analytic_plane(USE_SHARED_MEMORY);
 }
 #endif
 
@@ -654,6 +657,8 @@ int main(int argc, char* argv[])
   ::testing::FLAGS_gtest_death_test_style = "threadsafe";
   axom::slic::SimpleLogger logger;
 
+  SLIC_INFO(axom::fmt::format("USE_SHARED_MEMORY: {}", USE_SHARED_MEMORY));
+
   result = RUN_ALL_TESTS();
 
 #ifdef AXOM_USE_MPI

From 5fb886eda9e7f05472672eca9d63bda203d7aad0 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Fri, 5 Sep 2025 12:27:57 -0700
Subject: [PATCH 02/24] Fix some race conditions that prevented passage of
 quest_signed_distance_interface when run on multiple ranks. Remove build
 logic to limit the test to 1 rank.

---
 src/axom/quest/tests/CMakeLists.txt           |   3 -
 .../tests/quest_signed_distance_interface.cpp | 193 +++++++++++-------
 2 files changed, 120 insertions(+), 76 deletions(-)

diff --git a/src/axom/quest/tests/CMakeLists.txt b/src/axom/quest/tests/CMakeLists.txt
index 35da691a24..df8e61a954 100644
--- a/src/axom/quest/tests/CMakeLists.txt
+++ b/src/axom/quest/tests/CMakeLists.txt
@@ -142,9 +142,6 @@ foreach(test ${quest_mpi_tests})
     )
 
     set(_numMPITasks 4)
-    if (${test_name} STREQUAL "quest_signed_distance_interface")
-        set(_numMPITasks 1)
-    endif()
     if (${test_name} STREQUAL "quest_inout_interface")
         set(_numMPITasks 1)
     endif()
diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index ebfc1acdfa..bdf73604dc 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -57,85 +57,120 @@ constexpr bool USE_SHARED_MEMORY = false;
  * \brief Generate a mesh of 4 triangles along the XY plane.
  *
  * \param [in] file the file to write to.
+ * \param [in] comm The MPI communicator to use.
  *
  * \pre file.empty() == false.
  * \note Used primarily for debugging.
  */
-void generate_planar_mesh_stl_file(const std::string& file)
+void generate_planar_mesh_stl_file(const std::string& file, MPI_Comm comm = MPI_COMM_SELF)
 {
-  EXPECT_FALSE(file.empty());
-
-  std::ofstream ofs(file.c_str());
-  EXPECT_TRUE(ofs.is_open());
-
-  ofs << "solid plane" << std::endl;
-
-  // Triangle T1
-  ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
-  ofs << "\t\t outer loop" << std::endl;
-  ofs << "\t\t\t vertex -5.0 -5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex 5.0 -5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex 0.0  0.0 0.0" << std::endl;
-  ofs << "\t\t endloop" << std::endl;
-  ofs << "\t endfacet" << std::endl;
-
-  // Triangle T2
-  ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
-  ofs << "\t\t outer loop" << std::endl;
-  ofs << "\t\t\t vertex 5.0 -5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex 5.0  5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex 0.0  0.0 0.0" << std::endl;
-  ofs << "\t\t endloop" << std::endl;
-  ofs << "\t endfacet" << std::endl;
-
-  // Triangle T3
-  ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
-  ofs << "\t\t outer loop" << std::endl;
-  ofs << "\t\t\t vertex  5.0 5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex -5.0 5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex  0.0 0.0 0.0" << std::endl;
-  ofs << "\t\t endloop" << std::endl;
-  ofs << "\t endfacet" << std::endl;
-
-  // Triangle T4
-  ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
-  ofs << "\t\t outer loop" << std::endl;
-  ofs << "\t\t\t vertex -5.0  5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex -5.0 -5.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex  0.0  0.0 0.0" << std::endl;
-  ofs << "\t\t endloop" << std::endl;
-  ofs << "\t endfacet" << std::endl;
-
-  ofs << "endsolid" << std::endl;
-  ofs.close();
+  int rank = 0;
+  MPI_Comm_rank(comm, &rank);
+  if(rank == 0)
+  {
+    EXPECT_FALSE(file.empty());
+
+    std::ofstream ofs(file.c_str());
+    EXPECT_TRUE(ofs.is_open());
+
+    ofs << "solid plane" << std::endl;
+
+    // Triangle T1
+    ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
+    ofs << "\t\t outer loop" << std::endl;
+    ofs << "\t\t\t vertex -5.0 -5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex 5.0 -5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex 0.0  0.0 0.0" << std::endl;
+    ofs << "\t\t endloop" << std::endl;
+    ofs << "\t endfacet" << std::endl;
+
+    // Triangle T2
+    ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
+    ofs << "\t\t outer loop" << std::endl;
+    ofs << "\t\t\t vertex 5.0 -5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex 5.0  5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex 0.0  0.0 0.0" << std::endl;
+    ofs << "\t\t endloop" << std::endl;
+    ofs << "\t endfacet" << std::endl;
+
+    // Triangle T3
+    ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
+    ofs << "\t\t outer loop" << std::endl;
+    ofs << "\t\t\t vertex  5.0 5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex -5.0 5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex  0.0 0.0 0.0" << std::endl;
+    ofs << "\t\t endloop" << std::endl;
+    ofs << "\t endfacet" << std::endl;
+
+    // Triangle T4
+    ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
+    ofs << "\t\t outer loop" << std::endl;
+    ofs << "\t\t\t vertex -5.0  5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex -5.0 -5.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex  0.0  0.0 0.0" << std::endl;
+    ofs << "\t\t endloop" << std::endl;
+    ofs << "\t endfacet" << std::endl;
+
+    ofs << "endsolid" << std::endl;
+    ofs.close();
+  }
+  MPI_Barrier(comm);
 }
 
 /*!
  * \brief Generates a simple ASCII STL file consisting of a single triangle.
  *
  * \param [in] file the file to write to.
+ * \param [in] comm The MPI communicator to use.
  * \pre file.empty() == false.
  *
  * \note Used primarily for debugging.
  */
-void generate_stl_file(const std::string& file)
+void generate_stl_file(const std::string& file, MPI_Comm comm = MPI_COMM_SELF)
 {
-  EXPECT_FALSE(file.empty());
-
-  std::ofstream ofs(file.c_str());
-  EXPECT_TRUE(ofs.is_open());
-
-  ofs << "solid triangle" << std::endl;
-  ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
-  ofs << "\t\t outer loop" << std::endl;
-  ofs << "\t\t\t vertex 0.0 0.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex 1.0 0.0 0.0" << std::endl;
-  ofs << "\t\t\t vertex 0.0 1.0 0.0" << std::endl;
-  ofs << "\t\t endloop" << std::endl;
-  ofs << "\t endfacet" << std::endl;
-  ofs << "endsolid triangle" << std::endl;
-
-  ofs.close();
+  int rank = 0;
+  MPI_Comm_rank(comm, &rank);
+  if(rank == 0)
+  {
+    EXPECT_FALSE(file.empty());
+
+    std::ofstream ofs(file.c_str());
+    EXPECT_TRUE(ofs.is_open());
+
+    ofs << "solid triangle" << std::endl;
+    ofs << "\t facet normal 0.0 0.0 1.0" << std::endl;
+    ofs << "\t\t outer loop" << std::endl;
+    ofs << "\t\t\t vertex 0.0 0.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex 1.0 0.0 0.0" << std::endl;
+    ofs << "\t\t\t vertex 0.0 1.0 0.0" << std::endl;
+    ofs << "\t\t endloop" << std::endl;
+    ofs << "\t endfacet" << std::endl;
+    ofs << "endsolid triangle" << std::endl;
+
+    ofs.close();
+  }
+  MPI_Barrier(comm);
+}
+
+/*!
+ * \brief Remove a file using rank 0 of the supplied MPI communicator.
+ *
+ * \param fileName The name of the file to remove.
+ * \param comm The MPI communicator.
+ *
+ * \return 0 on success; non-zero otherwise.
+ */
+int removeFile(const std::string &fileName, MPI_Comm comm = MPI_COMM_WORLD)
+{
+  int rank = 0, retval = 0;
+  MPI_Comm_rank(comm, &rank);
+  MPI_Barrier(comm);
+  if(rank == 0)
+  {
+    retval = axom::utilities::filesystem::removeFile(fileName);
+  }
+  MPI_Bcast(&retval, 1, MPI_INT, 0, comm);
+  return retval;
 }
 
 /*!
@@ -185,8 +220,9 @@ void getUniformMesh(const UnstructuredMesh* mesh, mint::UniformMesh*& umesh)
 /*!
  * \brief Tests the signed against an anlytic surface mesh input.
  * \param [in] use_shared indicates whether to use shared memory or not.
+ * \param [in] comm The MPI communicator to use.
  */
-void check_analytic_plane(bool use_shared = false)
+void check_analytic_plane(bool use_shared = false, MPI_Comm comm = MPI_COMM_SELF)
 {
   // STEP 0: construct uniform box mesh
   constexpr int NDIMS = 3;
@@ -199,7 +235,7 @@ void check_analytic_plane(bool use_shared = false)
 
   // STEP 1: generate planar STL mesh file
   const std::string file = "plane.stl";
-  generate_planar_mesh_stl_file(file);
+  generate_planar_mesh_stl_file(file, comm);
 
   // STEP 2: define analytic plane corresponding to the planar mesh;
   const primal::Point<double, 3> origin {0.0, 0.0, 0.0};
@@ -209,7 +245,7 @@ void check_analytic_plane(bool use_shared = false)
   // STEP 2: initialize the signed distance
   quest::signed_distance_use_shared_memory(use_shared);
   quest::signed_distance_set_closed_surface(false);
-  quest::signed_distance_init(file);
+  quest::signed_distance_init(file, comm);
   EXPECT_TRUE(quest::signed_distance_initialized());
 
   axom::IndexType nnodes = mesh.getNumberOfNodes();
@@ -236,7 +272,7 @@ void check_analytic_plane(bool use_shared = false)
   EXPECT_FALSE(quest::signed_distance_initialized());
 
 #ifdef REMOVE_FILES
-  EXPECT_EQ(axom::utilities::filesystem::removeFile(file), 0);
+  EXPECT_EQ(removeFile(file, comm), 0);
 #endif
 }
 
@@ -353,7 +389,7 @@ TEST(quest_signed_distance_interface, initialize)
 
   // generate a temp STL file
   const std::string fileName = "test_triangle.stl";
-  generate_stl_file(fileName);
+  generate_stl_file(fileName, MPI_COMM_WORLD);
 
   // test valid initialization
   quest::signed_distance_set_dimension(3);
@@ -367,7 +403,7 @@ TEST(quest_signed_distance_interface, initialize)
 
   // remove temp STL file
 #ifdef REMOVE_FILES
-  EXPECT_EQ(axom::utilities::filesystem::removeFile(fileName), 0);
+  EXPECT_EQ(removeFile(fileName, MPI_COMM_WORLD), 0);
 #endif
 }
 
@@ -411,10 +447,19 @@ TEST(quest_signed_distance_interface, get_mesh_bounds)
 //------------------------------------------------------------------------------
 TEST(quest_signed_distance_interface, analytic_plane)
 {
-  check_analytic_plane();
+  // Serial test - Only call on 1 rank since the test creates/removes a file with
+  //               a fixed name.
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  if(rank == 0)
+  {
+    check_analytic_plane();
+  }
 
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
-  check_analytic_plane(USE_SHARED_MEMORY);
+  // We are using shared memory that we want to coordinate among ranks in
+  // MPI_COMM_WORLD so pass that communicator.
+  check_analytic_plane(USE_SHARED_MEMORY, MPI_COMM_WORLD);
 #endif
 }
 
@@ -422,8 +467,10 @@ TEST(quest_signed_distance_interface, analytic_plane)
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
 TEST(quest_signed_distance_interface, call_twice_using_shared_memory)
 {
-  check_analytic_plane(USE_SHARED_MEMORY);
-  check_analytic_plane(USE_SHARED_MEMORY);
+  // We are using shared memory that we want to coordinate among ranks in
+  // MPI_COMM_WORLD so pass that communicator.
+  check_analytic_plane(USE_SHARED_MEMORY, MPI_COMM_WORLD);
+  check_analytic_plane(USE_SHARED_MEMORY, MPI_COMM_WORLD);
 }
 #endif
 

From 7d4245d9ec62b5f1111580c82ef9a196ea24a9dc Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Fri, 5 Sep 2025 17:47:13 -0700
Subject: [PATCH 03/24] Fix issue in quest_signed_distance_interface test.
 Complete shared memory via Umpire, as far as I can tell.

---
 RELEASE-NOTES.md                              |  1 +
 .../quest/interface/internal/QuestHelpers.cpp | 79 +++++++++++++++----
 src/axom/quest/interface/signed_distance.cpp  | 28 +++----
 .../tests/quest_signed_distance_interface.cpp | 20 +++--
 4 files changed, 88 insertions(+), 40 deletions(-)

diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 5d85f2f9f5..8e562410e1 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -77,6 +77,7 @@ The Axom project release numbers follow [Semantic Versioning](http://semver.org/
   `NURBSCurve` and `NURBSPatch` classes and add overloads from `axom::ArrayView`
 - Core: Updates behavior of `FlatMap::reserve()` to only trigger a rehash if maximum load factor
   would be exceeded.
+- Quest: The signed_distance functions were modified so they use Umpire's shared memory mechanisms instead of using MPI3 directly.
 
 ###  Fixed
 - Core: prevent incorrect instantiations of `axom::Array` from a host-only compile, when Axom is compiled
diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index ce50416f75..a1928181b7 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -39,6 +39,55 @@ namespace internal
 /// Mesh I/O methods
 
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+/*
+ * Deallocates the specified MPI communicator object.
+ */
+static void mpi_comm_free(MPI_Comm* comm)
+{
+  if(*comm != MPI_COMM_NULL)
+  {
+    MPI_Comm_free(comm);
+  }
+}
+
+/*
+ * Creates inter-node and intra-node communicators from the given global
+ * MPI communicator handle.
+ */
+static void create_communicators(MPI_Comm global_comm,
+                          MPI_Comm& intra_node_comm,
+                          MPI_Comm& inter_node_comm,
+                          int& global_rank_id,
+                          int& local_rank_id,
+                          int& intercom_rank_id)
+{
+  // Sanity checks
+  SLIC_ASSERT(global_comm != MPI_COMM_NULL);
+  SLIC_ASSERT(intra_node_comm == MPI_COMM_NULL);
+  SLIC_ASSERT(inter_node_comm == MPI_COMM_NULL);
+
+  constexpr int IGNORE_KEY = 0;
+
+  // STEP 0: get global rank, used to order ranks in the inter-node comm.
+  MPI_Comm_rank(global_comm, &global_rank_id);
+
+  // STEP 1: create the intra-node communicator
+  MPI_Comm_split_type(global_comm, MPI_COMM_TYPE_SHARED, IGNORE_KEY, MPI_INFO_NULL, &intra_node_comm);
+  MPI_Comm_rank(intra_node_comm, &local_rank_id);
+  SLIC_ASSERT(local_rank_id >= 0);
+
+  // STEP 2: create inter-node communicator
+  const int color = (local_rank_id == 0) ? 1 : MPI_UNDEFINED;
+  MPI_Comm_split(global_comm, color, global_rank_id, &inter_node_comm);
+
+  if(color == 1)
+  {
+    MPI_Comm_rank(inter_node_comm, &intercom_rank_id);
+  }
+
+  SLIC_ASSERT(intra_node_comm != MPI_COMM_NULL);
+}
+
 /*!
  * \brief Allocates a shared memory buffer for the mesh that is shared among
  *  all the ranks within the same compute node.
@@ -172,23 +221,18 @@ int read_stl_mesh_shared(const std::string& file,
     return READ_FAILED;
   }
 
-  // STEP 1: Get the communicator from the Umpire allocator.
+  // STEP 1: Create communicators
   int global_rank_id = -1;
+  int local_rank_id = -1;
   int intercom_rank_id = -1;
-  MPI_Comm_rank(global_comm, &global_rank_id);
+  MPI_Comm intra_node_comm = MPI_COMM_NULL;
   MPI_Comm inter_node_comm = MPI_COMM_NULL;
-  umpire::ResourceManager& rm = umpire::ResourceManager::getInstance();
-  if(rm.isAllocator(allocatorID))
-  {
-    umpire::Allocator allocator = rm.getAllocator(allocatorID);
-    inter_node_comm = umpire::get_communicator_for_allocator(allocator, global_comm);
-    MPI_Comm_rank(inter_node_comm, &intercom_rank_id);
-std::cout << "Rank " << global_rank_id << ": intercom_rank_id=" << intercom_rank_id << std::endl;
-  }
-  else
-  {
-    SLIC_ERROR(axom::fmt::format("An invalid allocatorID {} was provided.", allocatorID));
-  }
+  create_communicators(global_comm,
+                       intra_node_comm,
+                       inter_node_comm,
+                       global_rank_id,
+                       local_rank_id,
+                       intercom_rank_id);
 
   // STEP 2: Exchange mesh metadata
   constexpr int NUM_NODES = 0;
@@ -200,6 +244,8 @@ std::cout << "Rank " << global_rank_id << ": intercom_rank_id=" << intercom_rank
   int rc = read_and_exchange_mesh_metadata(global_rank_id, global_comm, reader, mesh_metadata);
   if(rc != READ_SUCCESS)
   {
+    mpi_comm_free(&inter_node_comm);
+    mpi_comm_free(&intra_node_comm);
     return READ_FAILED;
   }
 
@@ -236,7 +282,10 @@ std::cout << "Rank " << global_rank_id << ": intercom_rank_id=" << intercom_rank
     MPI_Bcast(mesh_buffer, numBytes, MPI_UNSIGNED_CHAR, 0, inter_node_comm);
   }
 
-  // NOTE: Communicators are associated with Umpire allocators and Umpire will free them.
+  // STEP 6 free communicators
+  MPI_Barrier(global_comm);
+  mpi_comm_free(&inter_node_comm);
+  mpi_comm_free(&intra_node_comm);
 
   return READ_SUCCESS;
 }
diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index 3bacfe6224..d4336ccecc 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -136,21 +136,22 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
   // STEP 0: read the STL mesh
   int rc = INIT_FAILED;
 
-#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
-  if(s_allocator_id == INVALID_ALLOCATOR_ID)
-  {
-    // Make a shared memory allocator and get its id.
-    auto& rm = umpire::ResourceManager::getInstance();
-    auto traits{umpire::get_default_resource_traits("SHARED")};
-    traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
-    auto node_allocator{rm.makeResource("SHARED::node_allocator", traits)};
-    auto signed_distance_allocator{
-      rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>("signed_distance_allocator", node_allocator)};
-    s_allocator_id = signed_distance_allocator.getId();
-  }
-
   if(Parameters.use_shared_memory)
   {
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+    if(s_allocator_id == INVALID_ALLOCATOR_ID)
+    {
+      // Make a shared memory allocator if we have not made it before. We'll reuse
+      // the allocator to allocate different buffers (1 at a time).
+      auto& rm = umpire::ResourceManager::getInstance();
+      auto traits{umpire::get_default_resource_traits("SHARED")};
+      traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
+      auto node_allocator{rm.makeResource("SHARED::node_allocator", traits)};
+      auto signed_distance_allocator{
+        rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>("signed_distance_allocator", node_allocator)};
+      s_allocator_id = signed_distance_allocator.getId();
+    }
+
     rc = internal::read_stl_mesh_shared(file,
                                         comm,
                                         s_allocator_id,
@@ -161,7 +162,6 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
   {
     rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
   }
-
 #else
 
   SLIC_WARNING_IF(Parameters.use_shared_memory,
diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index bdf73604dc..79773782cd 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -219,10 +219,11 @@ void getUniformMesh(const UnstructuredMesh* mesh, mint::UniformMesh*& umesh)
 
 /*!
  * \brief Tests the signed against an anlytic surface mesh input.
+ * \param [in] file The name of the STL file to write.
  * \param [in] use_shared indicates whether to use shared memory or not.
  * \param [in] comm The MPI communicator to use.
  */
-void check_analytic_plane(bool use_shared = false, MPI_Comm comm = MPI_COMM_SELF)
+void check_analytic_plane(const std::string &file, bool use_shared = false, MPI_Comm comm = MPI_COMM_SELF)
 {
   // STEP 0: construct uniform box mesh
   constexpr int NDIMS = 3;
@@ -234,7 +235,6 @@ void check_analytic_plane(bool use_shared = false, MPI_Comm comm = MPI_COMM_SELF
   double* err = mesh.createField<double>("err", mint::NODE_CENTERED);
 
   // STEP 1: generate planar STL mesh file
-  const std::string file = "plane.stl";
   generate_planar_mesh_stl_file(file, comm);
 
   // STEP 2: define analytic plane corresponding to the planar mesh;
@@ -447,19 +447,17 @@ TEST(quest_signed_distance_interface, get_mesh_bounds)
 //------------------------------------------------------------------------------
 TEST(quest_signed_distance_interface, analytic_plane)
 {
-  // Serial test - Only call on 1 rank since the test creates/removes a file with
-  //               a fixed name.
+  // Serial test - called independently on each rank. In order to avoid problems
+  //               writing/reading the STL file, we pass a unique name for each
+  //               rank.
   int rank = 0;
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
-  if(rank == 0)
-  {
-    check_analytic_plane();
-  }
+  check_analytic_plane(axom::fmt::format("plane{}.stl", rank));
 
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
   // We are using shared memory that we want to coordinate among ranks in
   // MPI_COMM_WORLD so pass that communicator.
-  check_analytic_plane(USE_SHARED_MEMORY, MPI_COMM_WORLD);
+  check_analytic_plane("plane.stl", USE_SHARED_MEMORY, MPI_COMM_WORLD);
 #endif
 }
 
@@ -469,8 +467,8 @@ TEST(quest_signed_distance_interface, call_twice_using_shared_memory)
 {
   // We are using shared memory that we want to coordinate among ranks in
   // MPI_COMM_WORLD so pass that communicator.
-  check_analytic_plane(USE_SHARED_MEMORY, MPI_COMM_WORLD);
-  check_analytic_plane(USE_SHARED_MEMORY, MPI_COMM_WORLD);
+  check_analytic_plane("plane.stl", USE_SHARED_MEMORY, MPI_COMM_WORLD);
+  check_analytic_plane("plane.stl", USE_SHARED_MEMORY, MPI_COMM_WORLD);
 }
 #endif
 

From 4c73b35dd8a82bbfabf2665df776499afa59e01d Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Fri, 5 Sep 2025 17:47:49 -0700
Subject: [PATCH 04/24] Initial change to Axom spack package.py to select
 Umpire that has MPI3 shared memory support.

---
 scripts/spack/packages/axom/package.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/spack/packages/axom/package.py b/scripts/spack/packages/axom/package.py
index fa5ac0469b..68e9f4cffa 100644
--- a/scripts/spack/packages/axom/package.py
+++ b/scripts/spack/packages/axom/package.py
@@ -146,6 +146,7 @@ class Axom(CachedCMakePackage, CudaPackage, ROCmPackage):
         depends_on("umpire@6.0.0", when="@0.6.0")
         depends_on("umpire@5:5.0.1", when="@:0.5.0")
         depends_on("umpire+openmp", when="+openmp")
+        depends_on("umpire+mpi3_shmem", when="+mpi")
 
     with when("+raja"):
         depends_on("raja")

From 55d8f1c7549813074bbc430032ca0a9d8a915130 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Fri, 5 Sep 2025 18:13:59 -0700
Subject: [PATCH 05/24] make style

---
 .../quest/interface/internal/QuestHelpers.cpp | 34 ++++++++-----------
 .../quest/interface/internal/QuestHelpers.hpp |  3 +-
 src/axom/quest/interface/signed_distance.cpp  | 25 ++++++--------
 .../tests/quest_signed_distance_interface.cpp | 11 +++---
 4 files changed, 35 insertions(+), 38 deletions(-)

diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index a1928181b7..270589defb 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -23,7 +23,8 @@
   #endif
 #endif
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
+#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && \
+  (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
   #include "umpire/Umpire.hpp"
   #define AXOM_USE_UMPIRE_SHARED_MEMORY
 #endif
@@ -55,11 +56,11 @@ static void mpi_comm_free(MPI_Comm* comm)
  * MPI communicator handle.
  */
 static void create_communicators(MPI_Comm global_comm,
-                          MPI_Comm& intra_node_comm,
-                          MPI_Comm& inter_node_comm,
-                          int& global_rank_id,
-                          int& local_rank_id,
-                          int& intercom_rank_id)
+                                 MPI_Comm& intra_node_comm,
+                                 MPI_Comm& inter_node_comm,
+                                 int& global_rank_id,
+                                 int& local_rank_id,
+                                 int& intercom_rank_id)
 {
   // Sanity checks
   SLIC_ASSERT(global_comm != MPI_COMM_NULL);
@@ -117,12 +118,12 @@ static void create_communicators(MPI_Comm global_comm,
  * \post mesh_buffer != nullptr
  */
 static size_t allocate_shared_buffer(int allocatorID,
-                              const axom::IndexType mesh_metadata[2],
-                              double*& x,
-                              double*& y,
-                              double*& z,
-                              axom::IndexType*& conn,
-                              unsigned char*& mesh_buffer)
+                                     const axom::IndexType mesh_metadata[2],
+                                     double*& x,
+                                     double*& y,
+                                     double*& z,
+                                     axom::IndexType*& conn,
+                                     unsigned char*& mesh_buffer)
 {
   // Allocate the buffer.
   const axom::IndexType nnodes = mesh_metadata[0];
@@ -254,13 +255,8 @@ int read_stl_mesh_shared(const std::string& file,
   double* y = nullptr;
   double* z = nullptr;
   axom::IndexType* conn = nullptr;
-  const size_t numBytes = allocate_shared_buffer(allocatorID,
-                                                 mesh_metadata,
-                                                 x,
-                                                 y,
-                                                 z,
-                                                 conn,
-                                                 mesh_buffer);
+  const size_t numBytes =
+    allocate_shared_buffer(allocatorID, mesh_metadata, x, y, z, conn, mesh_buffer);
   SLIC_ASSERT(x != nullptr);
   SLIC_ASSERT(y != nullptr);
   SLIC_ASSERT(z != nullptr);
diff --git a/src/axom/quest/interface/internal/QuestHelpers.hpp b/src/axom/quest/interface/internal/QuestHelpers.hpp
index d350e875c1..1dcc9d805f 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.hpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.hpp
@@ -63,7 +63,8 @@ class ScopedLogLevelChanger
 /// \name Mesh I/O methods
 /// @{
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
+#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && \
+  (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
 
 /*!
  * \brief Reads in the surface mesh from the specified file into a shared
diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index d4336ccecc..3dfe039ba0 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -109,8 +109,8 @@ static int s_allocator_id = INVALID_ALLOCATOR_ID;
 static unsigned char* s_shared_mesh_buffer = nullptr;
 #else
 static std::string s_shared_memory_requirements(
-                      "Shared memory requires MPI and an Umpire library built with "
-                      "UMPIRE_ENABLE_IPC_SHARED_MEMORY set to ON");
+  "Shared memory requires MPI and an Umpire library built with "
+  "UMPIRE_ENABLE_IPC_SHARED_MEMORY set to ON");
 #endif
 
 }  // end anonymous namespace
@@ -144,19 +144,17 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
       // Make a shared memory allocator if we have not made it before. We'll reuse
       // the allocator to allocate different buffers (1 at a time).
       auto& rm = umpire::ResourceManager::getInstance();
-      auto traits{umpire::get_default_resource_traits("SHARED")};
+      auto traits {umpire::get_default_resource_traits("SHARED")};
       traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
-      auto node_allocator{rm.makeResource("SHARED::node_allocator", traits)};
-      auto signed_distance_allocator{
-        rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>("signed_distance_allocator", node_allocator)};
+      auto node_allocator {rm.makeResource("SHARED::node_allocator", traits)};
+      auto signed_distance_allocator {
+        rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>("signed_distance_allocator",
+                                                                    node_allocator)};
       s_allocator_id = signed_distance_allocator.getId();
     }
 
-    rc = internal::read_stl_mesh_shared(file,
-                                        comm,
-                                        s_allocator_id,
-                                        s_shared_mesh_buffer,
-                                        s_surface_mesh);
+    rc =
+      internal::read_stl_mesh_shared(file, comm, s_allocator_id, s_shared_mesh_buffer, s_surface_mesh);
   }
   else
   {
@@ -164,10 +162,9 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
   }
 #else
 
-  SLIC_WARNING_IF(Parameters.use_shared_memory,
-                  s_shared_memory_requirements_message);
+    SLIC_WARNING_IF(Parameters.use_shared_memory, s_shared_memory_requirements_message);
 
-  rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
+    rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
 #endif
 
   if(rc != 0)
diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index 79773782cd..0189144148 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -46,8 +46,9 @@ using UnstructuredMesh = mint::UnstructuredMesh<mint::SINGLE_SHAPE>;
 //------------------------------------------------------------------------------
 namespace
 {
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
-#define AXOM_USE_UMPIRE_SHARED_MEMORY
+#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && \
+  (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
+  #define AXOM_USE_UMPIRE_SHARED_MEMORY
 constexpr bool USE_SHARED_MEMORY = true;
 #else
 constexpr bool USE_SHARED_MEMORY = false;
@@ -160,7 +161,7 @@ void generate_stl_file(const std::string& file, MPI_Comm comm = MPI_COMM_SELF)
  *
  * \return 0 on success; non-zero otherwise.
  */
-int removeFile(const std::string &fileName, MPI_Comm comm = MPI_COMM_WORLD)
+int removeFile(const std::string& fileName, MPI_Comm comm = MPI_COMM_WORLD)
 {
   int rank = 0, retval = 0;
   MPI_Comm_rank(comm, &rank);
@@ -223,7 +224,9 @@ void getUniformMesh(const UnstructuredMesh* mesh, mint::UniformMesh*& umesh)
  * \param [in] use_shared indicates whether to use shared memory or not.
  * \param [in] comm The MPI communicator to use.
  */
-void check_analytic_plane(const std::string &file, bool use_shared = false, MPI_Comm comm = MPI_COMM_SELF)
+void check_analytic_plane(const std::string& file,
+                          bool use_shared = false,
+                          MPI_Comm comm = MPI_COMM_SELF)
 {
   // STEP 0: construct uniform box mesh
   constexpr int NDIMS = 3;

From ebab4a6d9816f107d349e6756b5d847bb1dd256d Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Fri, 5 Sep 2025 18:19:53 -0700
Subject: [PATCH 06/24] Fix variable name use.

---
 src/axom/quest/interface/signed_distance.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index 3dfe039ba0..77e70bfaff 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -162,7 +162,7 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
   }
 #else
 
-    SLIC_WARNING_IF(Parameters.use_shared_memory, s_shared_memory_requirements_message);
+    SLIC_WARNING_IF(Parameters.use_shared_memory, s_shared_memory_requirements);
 
     rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
 #endif

From 6adb053123ac4c80a579c0185cb417e2c1f626d9 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Fri, 5 Sep 2025 18:20:45 -0700
Subject: [PATCH 07/24] Change message about Umpire.

---
 src/axom/quest/interface/signed_distance.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index 77e70bfaff..ce8fa7291a 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -109,8 +109,7 @@ static int s_allocator_id = INVALID_ALLOCATOR_ID;
 static unsigned char* s_shared_mesh_buffer = nullptr;
 #else
 static std::string s_shared_memory_requirements(
-  "Shared memory requires MPI and an Umpire library built with "
-  "UMPIRE_ENABLE_IPC_SHARED_MEMORY set to ON");
+  "Shared memory requires MPI and an Umpire library built with shared memory support");
 #endif
 
 }  // end anonymous namespace

From 4684659513bcd728e0026bfff4e0db50e05999b7 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Mon, 8 Sep 2025 11:07:30 -0700
Subject: [PATCH 08/24] Fix old typo

---
 src/axom/quest/interface/internal/QuestHelpers.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index 270589defb..bc7f0665dc 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -94,7 +94,7 @@ static void create_communicators(MPI_Comm global_comm,
  *  all the ranks within the same compute node.
  *
  * \param [in] allocatorID A valid Umpire allocator id that can allocate shared memory.
- * \param [in] mesh_metada tuple with the number of nodes/faces on the mesh
+ * \param [in] mesh_metadata tuple with the number of nodes/faces on the mesh
  * \param [out] x pointer into the buffer where the x--coordinates are stored.
  * \param [out] y pointer into the buffer where the y--coordinates are stored.
  * \param [out] z pointer into the buffer where the z--coordinates are stored.

From cb19673e3cd2e13aee1fb9a5d0483c01a1a5bb6c Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Mon, 8 Sep 2025 11:07:48 -0700
Subject: [PATCH 09/24] Fix conditional compilation block.

---
 src/axom/quest/interface/signed_distance.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index ce8fa7291a..e9c06884e5 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -135,9 +135,9 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
   // STEP 0: read the STL mesh
   int rc = INIT_FAILED;
 
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
   if(Parameters.use_shared_memory)
   {
-#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
     if(s_allocator_id == INVALID_ALLOCATOR_ID)
     {
       // Make a shared memory allocator if we have not made it before. We'll reuse
@@ -160,10 +160,9 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
     rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
   }
 #else
+  SLIC_WARNING_IF(Parameters.use_shared_memory, s_shared_memory_requirements);
 
-    SLIC_WARNING_IF(Parameters.use_shared_memory, s_shared_memory_requirements);
-
-    rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
+  rc = internal::read_stl_mesh(file, s_surface_mesh, comm);
 #endif
 
   if(rc != 0)

From 73ea86a262acc1adbdce424019d7feab71748e76 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Mon, 8 Sep 2025 11:09:08 -0700
Subject: [PATCH 10/24] Removed extra dashes.

---
 src/axom/quest/interface/internal/QuestHelpers.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index bc7f0665dc..0851894e19 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -95,9 +95,9 @@ static void create_communicators(MPI_Comm global_comm,
  *
  * \param [in] allocatorID A valid Umpire allocator id that can allocate shared memory.
  * \param [in] mesh_metadata tuple with the number of nodes/faces on the mesh
- * \param [out] x pointer into the buffer where the x--coordinates are stored.
- * \param [out] y pointer into the buffer where the y--coordinates are stored.
- * \param [out] z pointer into the buffer where the z--coordinates are stored.
+ * \param [out] x pointer into the buffer where the x-coordinates are stored.
+ * \param [out] y pointer into the buffer where the y-coordinates are stored.
+ * \param [out] z pointer into the buffer where the z-coordinates are stored.
  * \param [out] conn pointer into the buffer consisting the cell-connectivity.
  * \param [out] mesh_buffer raw buffer consisting of all the mesh data.
  *

From f12ff686bae8f27cbb2b93f3483b53e05f3695a2 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Mon, 8 Sep 2025 13:00:41 -0700
Subject: [PATCH 11/24] Avoid direct MPI calls for case when this MPI test is
 actually NOT used with MPI.

---
 .../tests/quest_signed_distance_interface.cpp | 48 ++++++++++++++-----
 1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index 0189144148..734de56178 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -54,6 +54,33 @@ constexpr bool USE_SHARED_MEMORY = true;
 constexpr bool USE_SHARED_MEMORY = false;
 #endif
 
+// NOTE: This test can actually be built in serial so we provide parallel and
+//       serial versions of these functions.
+#ifdef AXOM_USE_UMPIRE_SHARED_MEMORY
+// Parallel versions
+int comm_rank(MPI_Comm comm)
+{
+  int rank = 0;
+  MPI_Comm_rank(comm, &rank);
+  return rank;
+}
+void barrier(MPI_Comm comm) { MPI_Barrier(comm); }
+void bcast_int(int& value, MPI_Comm comm) { MPI_Bcast(&value, 1, MPI_INT, 0, comm); }
+#else
+// Serial versions
+constexpr int MPI_COMM_WORLD = -1;
+
+int comm_rank(MPI_Comm comm) { return 0; }
+void barrier(MPI_Comm)
+{
+  // no-op
+}
+void bcast_int(int&)
+{
+  // no-op
+}
+#endif
+
 /*!
  * \brief Generate a mesh of 4 triangles along the XY plane.
  *
@@ -65,8 +92,7 @@ constexpr bool USE_SHARED_MEMORY = false;
  */
 void generate_planar_mesh_stl_file(const std::string& file, MPI_Comm comm = MPI_COMM_SELF)
 {
-  int rank = 0;
-  MPI_Comm_rank(comm, &rank);
+  int rank = comm_rank(comm);
   if(rank == 0)
   {
     EXPECT_FALSE(file.empty());
@@ -115,7 +141,7 @@ void generate_planar_mesh_stl_file(const std::string& file, MPI_Comm comm = MPI_
     ofs << "endsolid" << std::endl;
     ofs.close();
   }
-  MPI_Barrier(comm);
+  barrier(comm);
 }
 
 /*!
@@ -129,8 +155,7 @@ void generate_planar_mesh_stl_file(const std::string& file, MPI_Comm comm = MPI_
  */
 void generate_stl_file(const std::string& file, MPI_Comm comm = MPI_COMM_SELF)
 {
-  int rank = 0;
-  MPI_Comm_rank(comm, &rank);
+  int rank = comm_rank(comm);
   if(rank == 0)
   {
     EXPECT_FALSE(file.empty());
@@ -150,7 +175,7 @@ void generate_stl_file(const std::string& file, MPI_Comm comm = MPI_COMM_SELF)
 
     ofs.close();
   }
-  MPI_Barrier(comm);
+  barrier(comm);
 }
 
 /*!
@@ -163,14 +188,14 @@ void generate_stl_file(const std::string& file, MPI_Comm comm = MPI_COMM_SELF)
  */
 int removeFile(const std::string& fileName, MPI_Comm comm = MPI_COMM_WORLD)
 {
-  int rank = 0, retval = 0;
-  MPI_Comm_rank(comm, &rank);
-  MPI_Barrier(comm);
+  int retval = 0;
+  int rank = comm_rank(comm);
+  barrier(comm);
   if(rank == 0)
   {
     retval = axom::utilities::filesystem::removeFile(fileName);
   }
-  MPI_Bcast(&retval, 1, MPI_INT, 0, comm);
+  bcast_int(retval, comm);
   return retval;
 }
 
@@ -453,8 +478,7 @@ TEST(quest_signed_distance_interface, analytic_plane)
   // Serial test - called independently on each rank. In order to avoid problems
   //               writing/reading the STL file, we pass a unique name for each
   //               rank.
-  int rank = 0;
-  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  int rank = comm_rank(MPI_COMM_WORLD);
   check_analytic_plane(axom::fmt::format("plane{}.stl", rank));
 
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)

From 88fa4504201492c2f9042068fed20591f61a4212 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Mon, 8 Sep 2025 13:03:33 -0700
Subject: [PATCH 12/24] Fix mistake

---
 src/axom/quest/tests/quest_signed_distance_interface.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index 734de56178..68e902e7cd 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -75,7 +75,7 @@ void barrier(MPI_Comm)
 {
   // no-op
 }
-void bcast_int(int&)
+void bcast_int(int&, MPI_Comm)
 {
   // no-op
 }

From 5aa1325f46829784c59ee6c0ca35db51d184d178 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Mon, 8 Sep 2025 14:19:29 -0700
Subject: [PATCH 13/24] Change macro used to select MPI abstraction functions.

---
 src/axom/quest/tests/quest_signed_distance_interface.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index 68e902e7cd..f6d694071f 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -56,7 +56,7 @@ constexpr bool USE_SHARED_MEMORY = false;
 
 // NOTE: This test can actually be built in serial so we provide parallel and
 //       serial versions of these functions.
-#ifdef AXOM_USE_UMPIRE_SHARED_MEMORY
+#if defined(AXOM_USE_MPI)
 // Parallel versions
 int comm_rank(MPI_Comm comm)
 {

From f1149865ec60ddc83c3c1e54e96742e6f385b22a Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Mon, 8 Sep 2025 16:47:12 -0700
Subject: [PATCH 14/24] Moved a function so it is more like the previous
 ordering.

---
 .../quest/interface/internal/QuestHelpers.cpp | 106 +++++++++---------
 1 file changed, 53 insertions(+), 53 deletions(-)

diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index 0851894e19..aa7fef7def 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -40,8 +40,8 @@ namespace internal
 /// Mesh I/O methods
 
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
-/*
- * Deallocates the specified MPI communicator object.
+/*!
+ * \brief Deallocates the specified MPI communicator object.
  */
 static void mpi_comm_free(MPI_Comm* comm)
 {
@@ -51,9 +51,56 @@ static void mpi_comm_free(MPI_Comm* comm)
   }
 }
 
-/*
- * Creates inter-node and intra-node communicators from the given global
- * MPI communicator handle.
+/*!
+ * \brief Reads the mesh on rank 0 and exchanges the mesh metadata, i.e., the
+ *        number of nodes and faces with all other ranks.
+ *
+ * \param [in] global_rank_id MPI rank w.r.t. the global communicator
+ * \param [in] global_comm handle to the global communicator
+ * \param [in,out] reader the corresponding STL reader
+ * \param [out] mesh_metadata an array consisting of the mesh metadata.
+ *
+ * \note This method calls read() on the reader on rank 0.
+ *
+ * \pre global_comm != MPI_COMM_NULL
+ * \pre mesh_metadata != nullptr
+ */
+static int read_and_exchange_mesh_metadata(int global_rank_id,
+                                           MPI_Comm global_comm,
+                                           quest::STLReader& reader,
+                                           axom::IndexType mesh_metadata[2])
+{
+  constexpr int NUM_NODES = 0;
+  constexpr int NUM_FACES = 1;
+  constexpr int ROOT_RANK = 0;
+
+  switch(global_rank_id)
+  {
+  case 0:
+    if(reader.read() == READ_SUCCESS)
+    {
+      mesh_metadata[NUM_NODES] = reader.getNumNodes();
+      mesh_metadata[NUM_FACES] = reader.getNumFaces();
+    }
+    else
+    {
+      SLIC_WARNING("reading STL file failed, setting mesh to NULL");
+      mesh_metadata[NUM_NODES] = READ_FAILED;
+      mesh_metadata[NUM_FACES] = READ_FAILED;
+    }
+    MPI_Bcast(mesh_metadata, 2, axom::mpi_traits<axom::IndexType>::type, ROOT_RANK, global_comm);
+    break;
+  default:
+    MPI_Bcast(mesh_metadata, 2, axom::mpi_traits<axom::IndexType>::type, ROOT_RANK, global_comm);
+  }
+
+  int rc = (mesh_metadata[NUM_NODES] == READ_FAILED) ? READ_FAILED : READ_SUCCESS;
+  return rc;
+}
+
+/*!
+ * \brief Creates inter-node and intra-node communicators from the given global
+ *        MPI communicator handle.
  */
 static void create_communicators(MPI_Comm global_comm,
                                  MPI_Comm& intra_node_comm,
@@ -146,53 +193,6 @@ static size_t allocate_shared_buffer(int allocatorID,
   return (bytesize);
 }
 
-/*!
- * \brief Reads the mesh on rank 0 and exchanges the mesh metadata, i.e., the
- *  number of nodes and faces with all other ranks.
- *
- * \param [in] global_rank_id MPI rank w.r.t. the global communicator
- * \param [in] global_comm handle to the global communicator
- * \param [in,out] reader the corresponding STL reader
- * \param [out] mesh_metadata an array consisting of the mesh metadata.
- *
- * \note This method calls read() on the reader on rank 0.
- *
- * \pre global_comm != MPI_COMM_NULL
- * \pre mesh_metadata != nullptr
- */
-static int read_and_exchange_mesh_metadata(int global_rank_id,
-                                           MPI_Comm global_comm,
-                                           quest::STLReader& reader,
-                                           axom::IndexType mesh_metadata[2])
-{
-  constexpr int NUM_NODES = 0;
-  constexpr int NUM_FACES = 1;
-  constexpr int ROOT_RANK = 0;
-
-  switch(global_rank_id)
-  {
-  case 0:
-    if(reader.read() == READ_SUCCESS)
-    {
-      mesh_metadata[NUM_NODES] = reader.getNumNodes();
-      mesh_metadata[NUM_FACES] = reader.getNumFaces();
-    }
-    else
-    {
-      SLIC_WARNING("reading STL file failed, setting mesh to NULL");
-      mesh_metadata[NUM_NODES] = READ_FAILED;
-      mesh_metadata[NUM_FACES] = READ_FAILED;
-    }
-    MPI_Bcast(mesh_metadata, 2, axom::mpi_traits<axom::IndexType>::type, ROOT_RANK, global_comm);
-    break;
-  default:
-    MPI_Bcast(mesh_metadata, 2, axom::mpi_traits<axom::IndexType>::type, ROOT_RANK, global_comm);
-  }
-
-  int rc = (mesh_metadata[NUM_NODES] == READ_FAILED) ? READ_FAILED : READ_SUCCESS;
-  return rc;
-}
-
 /*
  * Reads in the surface mesh from the specified file into a shared
  * memory buffer that is attached to the given MPI shared window.
@@ -222,7 +222,7 @@ int read_stl_mesh_shared(const std::string& file,
     return READ_FAILED;
   }
 
-  // STEP 1: Create communicators
+  // STEP 1: Create intra-node and inter-node MPI communicators
   int global_rank_id = -1;
   int local_rank_id = -1;
   int intercom_rank_id = -1;

From 0ddce42421fb52199f703edc0928fa383d9258c0 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 12:31:00 -0700
Subject: [PATCH 15/24] Make AXOM_USE_UMPIRE_SHARED_MEMORY be set in config.hpp

---
 RELEASE-NOTES.md                              |  2 ++
 src/axom/config.hpp.in                        |  6 +++++-
 .../quest/interface/internal/QuestHelpers.cpp |  6 ------
 .../quest/interface/internal/QuestHelpers.hpp |  5 ++---
 src/axom/quest/interface/signed_distance.cpp  |  9 +++------
 .../tests/quest_signed_distance_interface.cpp |  4 +---
 .../thirdparty/SetupAxomThirdParty.cmake      | 19 +++++++++++++++++++
 7 files changed, 32 insertions(+), 19 deletions(-)

diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 8e562410e1..512a005928 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -78,6 +78,8 @@ The Axom project release numbers follow [Semantic Versioning](http://semver.org/
 - Core: Updates behavior of `FlatMap::reserve()` to only trigger a rehash if maximum load factor
   would be exceeded.
 - Quest: The signed_distance functions were modified so they use Umpire's shared memory mechanisms instead of using MPI3 directly.
+- Axom's `AXOM_USE_MPI3` CMake build option and corresponding macro definition were removed.
+- When Umpire is present, Axom now detects whether it supports shared memory and defines the `AXOM_USE_UMPIRE_SHARED_MEMORY` macro if appropriate. This macro can be used to conditionally compile code involving shared memory via Umpire.
 
 ###  Fixed
 - Core: prevent incorrect instantiations of `axom::Array` from a host-only compile, when Axom is compiled
diff --git a/src/axom/config.hpp.in b/src/axom/config.hpp.in
index 5ea85a6f2c..83449df43a 100644
--- a/src/axom/config.hpp.in
+++ b/src/axom/config.hpp.in
@@ -54,7 +54,6 @@
 #cmakedefine AXOM_USE_CUDA
 #cmakedefine AXOM_USE_HIP
 #cmakedefine AXOM_USE_MPI
-#cmakedefine AXOM_USE_MPI3
 #cmakedefine AXOM_USE_MPIF_HEADER
 #cmakedefine AXOM_USE_OPENMP
 
@@ -77,6 +76,11 @@
 #cmakedefine AXOM_USE_SPARSEHASH
 #cmakedefine AXOM_USE_UMPIRE
 
+/*
+ * Compiler defines for library capabilities
+ */
+#cmakedefine AXOM_USE_UMPIRE_SHARED_MEMORY
+
 /*
  * Compiler defines for third-party executables
  */
diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index aa7fef7def..d49a3238be 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -23,12 +23,6 @@
   #endif
 #endif
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && \
-  (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
-  #include "umpire/Umpire.hpp"
-  #define AXOM_USE_UMPIRE_SHARED_MEMORY
-#endif
-
 #include <limits>
 
 namespace axom
diff --git a/src/axom/quest/interface/internal/QuestHelpers.hpp b/src/axom/quest/interface/internal/QuestHelpers.hpp
index 1dcc9d805f..a318b2ca73 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.hpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.hpp
@@ -63,12 +63,11 @@ class ScopedLogLevelChanger
 /// \name Mesh I/O methods
 /// @{
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && \
-  (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
 
 /*!
  * \brief Reads in the surface mesh from the specified file into a shared
- *  memory buffer that is attached to the given MPI shared window.
+ *  memory buffer.
  *
  * \param [in] file the file consisting of the surface mesh
  * \param [in] global_comm handle to the global MPI communicator
diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index e9c06884e5..e63e9dca03 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -13,13 +13,10 @@
 
 #include "axom/slic/interface/slic.hpp"
 
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE)
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
   #include "umpire/Umpire.hpp"
-  #if defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY)
-    #include "umpire/strategy/NamedAllocationStrategy.hpp"
-    #include "umpire/util/MemoryResourceTraits.hpp"
-    #define AXOM_USE_UMPIRE_SHARED_MEMORY
-  #endif
+  #include "umpire/strategy/NamedAllocationStrategy.hpp"
+  #include "umpire/util/MemoryResourceTraits.hpp"
 #endif
 
 #ifdef AXOM_USE_MPI
diff --git a/src/axom/quest/tests/quest_signed_distance_interface.cpp b/src/axom/quest/tests/quest_signed_distance_interface.cpp
index f6d694071f..afd4bc8e5a 100644
--- a/src/axom/quest/tests/quest_signed_distance_interface.cpp
+++ b/src/axom/quest/tests/quest_signed_distance_interface.cpp
@@ -46,9 +46,7 @@ using UnstructuredMesh = mint::UnstructuredMesh<mint::SINGLE_SHAPE>;
 //------------------------------------------------------------------------------
 namespace
 {
-#if defined(AXOM_USE_MPI) && defined(AXOM_USE_UMPIRE) && \
-  (defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY))
-  #define AXOM_USE_UMPIRE_SHARED_MEMORY
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
 constexpr bool USE_SHARED_MEMORY = true;
 #else
 constexpr bool USE_SHARED_MEMORY = false;
diff --git a/src/cmake/thirdparty/SetupAxomThirdParty.cmake b/src/cmake/thirdparty/SetupAxomThirdParty.cmake
index 97a13e77a9..78d177c519 100644
--- a/src/cmake/thirdparty/SetupAxomThirdParty.cmake
+++ b/src/cmake/thirdparty/SetupAxomThirdParty.cmake
@@ -57,6 +57,25 @@ if (UMPIRE_DIR)
     set(UMPIRE_FOUND TRUE)
 
     blt_convert_to_system_includes(TARGET umpire)
+
+    # Check whether the Umpire defines symbols for shared memory
+    blt_check_code_compiles(CODE_COMPILES UMPIRE_SHARED_MEMORY
+                            VERBOSE_OUTPUT OFF
+                            DEPENDS_ON umpire
+                            SOURCE_STRING "
+    #include <umpire/config.hpp>
+    #if defined(UMPIRE_ENABLE_IPC_SHARED_MEMORY) || defined(UMPIRE_ENABLE_MPI3_SHARED_MEMORY)
+    int main() { return 0; }
+    #else
+    #error Macros not defined
+    #endif
+    ")
+    if (AXOM_ENABLE_MPI AND UMPIRE_SHARED_MEMORY)
+        set(AXOM_USE_UMPIRE_SHARED_MEMORY TRUE)
+    else()
+        set(AXOM_USE_UMPIRE_SHARED_MEMORY FALSE)
+    endif()
+    message(STATUS "Umpire supports shared memory: ${AXOM_USE_UMPIRE_SHARED_MEMORY}")
 else()
     message(STATUS "Umpire support is OFF")
     set(UMPIRE_FOUND FALSE)

From 40c11f110776a2912994988f89acd8b4f15f1deb Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 12:33:32 -0700
Subject: [PATCH 16/24] Removed MPI build option.

---
 src/cmake/AxomOptions.cmake | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/cmake/AxomOptions.cmake b/src/cmake/AxomOptions.cmake
index 754e473df3..12a0683595 100644
--- a/src/cmake/AxomOptions.cmake
+++ b/src/cmake/AxomOptions.cmake
@@ -44,9 +44,6 @@ cmake_dependent_option(AXOM_ENABLE_DOCS "Enables Axom Docs" ON "ENABLE_DOCS" OFF
 cmake_dependent_option(AXOM_ENABLE_EXAMPLES "Enables Axom Examples" ON "ENABLE_EXAMPLES" OFF)
 option(AXOM_ENABLE_TOOLS "Enables Axom Tools" ON)
 
-cmake_dependent_option(AXOM_ENABLE_MPI3 "Enables use of MPI-3 features" OFF "ENABLE_MPI" OFF)
-mark_as_advanced(AXOM_ENABLE_MPI3)
-
 #--------------------------------------------------------------------------
 # Option to control whether AXOM_DEFINE compiler define is enabled
 #

From ee8de792a1f0fa2436e899cdb65cdbccaa3644f6 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 15:04:36 -0700
Subject: [PATCH 17/24] Moved shared memory allocator to core.

---
 src/axom/core/CMakeLists.txt                  |  1 +
 src/axom/core/memory_management.cpp           | 58 +++++++++++++++++++
 src/axom/core/memory_management.hpp           | 17 ++++++
 src/axom/core/tests/CMakeLists.txt            |  3 +-
 src/axom/core/tests/core_mpi_main.cpp         |  1 +
 src/axom/core/tests/core_shared_memory.hpp    | 52 +++++++++++++++++
 .../quest/interface/internal/QuestHelpers.cpp | 11 +---
 .../quest/interface/internal/QuestHelpers.hpp |  2 -
 src/axom/quest/interface/signed_distance.cpp  | 17 +-----
 9 files changed, 135 insertions(+), 27 deletions(-)
 create mode 100644 src/axom/core/memory_management.cpp
 create mode 100644 src/axom/core/tests/core_shared_memory.hpp

diff --git a/src/axom/core/CMakeLists.txt b/src/axom/core/CMakeLists.txt
index 89fa639774..77ec820ef2 100644
--- a/src/axom/core/CMakeLists.txt
+++ b/src/axom/core/CMakeLists.txt
@@ -107,6 +107,7 @@ set(core_sources
 
     numerics/polynomial_solvers.cpp
 
+    memory_management.cpp
     Path.cpp
     Types.cpp
     )
diff --git a/src/axom/core/memory_management.cpp b/src/axom/core/memory_management.cpp
new file mode 100644
index 0000000000..29bd8975f6
--- /dev/null
+++ b/src/axom/core/memory_management.cpp
@@ -0,0 +1,58 @@
+// Copyright (c) 2017-2025, Lawrence Livermore National Security, LLC and
+// other Axom Project Developers. See the top-level LICENSE file for details.
+//
+// SPDX-License-Identifier: (BSD-3-Clause)
+
+#include "axom/core/memory_management.hpp"
+
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+  #include "umpire/Umpire.hpp"
+  #include "umpire/strategy/NamedAllocationStrategy.hpp"
+  #include "umpire/util/MemoryResourceTraits.hpp"
+#endif
+
+namespace axom
+{
+
+bool isSharedMemoryAllocator(int allocID)
+{
+  bool isShared = false;
+#if defined(AXOM_USE_UMPIRE)
+  umpire::ResourceManager& rm = umpire::ResourceManager::getInstance();
+  if(rm.isAllocator(allocID))
+  {
+    umpire::Allocator allocator = rm.getAllocator(allocID);
+
+    isShared = allocator.getAllocationStrategy()->getTraits().resource ==
+                 umpire::MemoryResourceTraits::resource_type::shared;
+  }
+#endif
+  return isShared;
+}
+
+int getSharedMemoryAllocatorID()
+{
+  int allocator_id = INVALID_ALLOCATOR_ID;
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+  const std::string allocatorName("axom_named_allocator");
+  auto& rm = umpire::ResourceManager::getInstance();
+  if(!rm.isAllocator(allocatorName))
+  {
+    // Create the allocator
+    auto traits {umpire::get_default_resource_traits("SHARED")};
+    traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
+    auto axom_node_allocator {rm.makeResource("SHARED::axom_node_allocator", traits)};
+    auto axom_named_allocator {
+          rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>(allocatorName,
+                                                                      axom_node_allocator)};
+    allocator_id = axom_named_allocator.getId();
+  }
+  else
+  {
+    allocator_id = rm.getAllocator(allocatorName).getId();
+  }
+#endif
+  return allocator_id;
+}
+
+} // end namespace axom
diff --git a/src/axom/core/memory_management.hpp b/src/axom/core/memory_management.hpp
index 9ee550ab81..59acc91238 100644
--- a/src/axom/core/memory_management.hpp
+++ b/src/axom/core/memory_management.hpp
@@ -542,6 +542,23 @@ inline bool isDeviceAllocator(int allocator_id)
 inline bool isDeviceAllocator(int AXOM_UNUSED_PARAM(allocator_id)) { return false; }
 #endif
 
+/*!
+ * \brief Determines whether an allocator id is for shared memory.
+ *
+ * \param allocID An allocator id.
+ *
+ * \return True if the allocator id is for shared memory; false otherwise.
+ */
+bool isSharedMemoryAllocator(int allocID);
+
+/*!
+ * \brief Get the allocator ID for Axom's shared memory allocator.
+ *
+ * \return The allocator ID for Axom's shared memory allocator (if Axom is using Umpire),
+ *         or INVALID_ALLOCATOR_ID otherwise.
+ */
+int getSharedMemoryAllocatorID();
+
 }  // namespace axom
 
 #endif /* AXOM_MEMORYMANAGEMENT_HPP_ */
diff --git a/src/axom/core/tests/CMakeLists.txt b/src/axom/core/tests/CMakeLists.txt
index 60bc0779d8..854ca85edc 100644
--- a/src/axom/core/tests/CMakeLists.txt
+++ b/src/axom/core/tests/CMakeLists.txt
@@ -104,6 +104,7 @@ axom_add_test( NAME    core_collections
 if (AXOM_ENABLE_MPI)
   set( core_mpi_tests
        core_types.hpp
+       core_shared_memory.hpp
        )
 
   axom_add_executable(NAME       core_mpi_tests
@@ -117,7 +118,7 @@ if (AXOM_ENABLE_MPI)
     get_filename_component( test_suite ${test_suite} NAME_WE )
     axom_add_test( NAME          ${test_suite}_mpi
                    COMMAND       core_mpi_tests --gtest_filter=${test_suite}*
-                   NUM_MPI_TASKS 1 )
+                   NUM_MPI_TASKS 2 )
   endforeach()
 endif()
 
diff --git a/src/axom/core/tests/core_mpi_main.cpp b/src/axom/core/tests/core_mpi_main.cpp
index 4eae819475..ffa2653362 100644
--- a/src/axom/core/tests/core_mpi_main.cpp
+++ b/src/axom/core/tests/core_mpi_main.cpp
@@ -10,6 +10,7 @@
 #include "axom/config.hpp"
 
 #include "core_types.hpp"
+#include "core_shared_memory.hpp"
 
 int main(int argc, char* argv[])
 {
diff --git a/src/axom/core/tests/core_shared_memory.hpp b/src/axom/core/tests/core_shared_memory.hpp
new file mode 100644
index 0000000000..0819f48e29
--- /dev/null
+++ b/src/axom/core/tests/core_shared_memory.hpp
@@ -0,0 +1,52 @@
+// Copyright (c) 2017-2025, Lawrence Livermore National Security, LLC and
+// other Axom Project Developers. See the top-level LICENSE file for details.
+//
+// SPDX-License-Identifier: (BSD-3-Clause)
+
+// Axom includes
+#include "axom/config.hpp"
+#include "axom/core/memory_management.hpp"
+
+// gtest includes
+#include "gtest/gtest.h"
+
+#include <mpi.h>
+
+//------------------------------------------------------------------------------
+#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+TEST(core_shared_memory, shared_memory_allocator)
+{
+  EXPECT_FALSE(axom::isSharedMemoryAllocator(axom::getDefaultAllocatorID()));
+  EXPECT_TRUE(axom::isSharedMemoryAllocator(axom::getSharedMemoryAllocatorID()));
+
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  // Allocate shared memory
+  constexpr int sizes[] = {1024, 4096, 1000000};
+  for(int si = 0; si < 3; si++)
+  {
+    const int N = sizes[si];
+    int *buffer = axom::allocate<int>(N, axom::getSharedMemoryAllocatorID());
+
+    // Populate the shared memory on rank 0
+    if(rank == 0)
+    {
+      for(int i = 0; i < N; i++)
+      {
+        buffer[i] = i;
+      }
+    }
+
+    MPI_Barrier(MPI_COMM_WORLD);
+
+    // Test the shared memory on all ranks.
+    for(int i = 0; i < N; i++)
+    {
+      EXPECT_EQ(buffer[i], i);
+    }
+
+    axom::deallocate(buffer);
+  }
+}
+#endif
diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index d49a3238be..557b6a3ca4 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -134,7 +134,6 @@ static void create_communicators(MPI_Comm global_comm,
  * \brief Allocates a shared memory buffer for the mesh that is shared among
  *  all the ranks within the same compute node.
  *
- * \param [in] allocatorID A valid Umpire allocator id that can allocate shared memory.
  * \param [in] mesh_metadata tuple with the number of nodes/faces on the mesh
  * \param [out] x pointer into the buffer where the x-coordinates are stored.
  * \param [out] y pointer into the buffer where the y-coordinates are stored.
@@ -144,7 +143,6 @@ static void create_communicators(MPI_Comm global_comm,
  *
  * \return bytesize the number of bytes in the raw buffer.
  *
- * \pre allocatorID is a valid shared memory allocator.
  * \pre mesh_metadata != nullptr
  * \pre x == nullptr
  * \pre y == nullptr
@@ -158,8 +156,7 @@ static void create_communicators(MPI_Comm global_comm,
  * \post coon != nullptr
  * \post mesh_buffer != nullptr
  */
-static size_t allocate_shared_buffer(int allocatorID,
-                                     const axom::IndexType mesh_metadata[2],
+static size_t allocate_shared_buffer(const axom::IndexType mesh_metadata[2],
                                      double*& x,
                                      double*& y,
                                      double*& z,
@@ -170,7 +167,7 @@ static size_t allocate_shared_buffer(int allocatorID,
   const axom::IndexType nnodes = mesh_metadata[0];
   const axom::IndexType nfaces = mesh_metadata[1];
   const size_t bytesize = nnodes * 3 * sizeof(double) + nfaces * 3 * sizeof(axom::IndexType);
-  mesh_buffer = allocate<unsigned char>(bytesize, allocatorID);
+  mesh_buffer = allocate<unsigned char>(bytesize, getSharedMemoryAllocatorID());
 
   // calculate offset to the coordinates & cell connectivity in the buffer
   int baseOffset = nnodes * sizeof(double);
@@ -193,12 +190,10 @@ static size_t allocate_shared_buffer(int allocatorID,
  */
 int read_stl_mesh_shared(const std::string& file,
                          MPI_Comm global_comm,
-                         int allocatorID,
                          unsigned char*& mesh_buffer,
                          mint::Mesh*& m)
 {
   SLIC_ASSERT(global_comm != MPI_COMM_NULL);
-  SLIC_ASSERT(allocatorID != INVALID_ALLOCATOR_ID);
 
   // NOTE: STL meshes are always 3D mesh consisting of triangles.
   using TriangleMesh = mint::UnstructuredMesh<mint::SINGLE_SHAPE>;
@@ -250,7 +245,7 @@ int read_stl_mesh_shared(const std::string& file,
   double* z = nullptr;
   axom::IndexType* conn = nullptr;
   const size_t numBytes =
-    allocate_shared_buffer(allocatorID, mesh_metadata, x, y, z, conn, mesh_buffer);
+    allocate_shared_buffer(mesh_metadata, x, y, z, conn, mesh_buffer);
   SLIC_ASSERT(x != nullptr);
   SLIC_ASSERT(y != nullptr);
   SLIC_ASSERT(z != nullptr);
diff --git a/src/axom/quest/interface/internal/QuestHelpers.hpp b/src/axom/quest/interface/internal/QuestHelpers.hpp
index a318b2ca73..dcec418d43 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.hpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.hpp
@@ -71,7 +71,6 @@ class ScopedLogLevelChanger
  *
  * \param [in] file the file consisting of the surface mesh
  * \param [in] global_comm handle to the global MPI communicator
- * \param [in] allocatorID An UMPIRE allocator ID that can allocate shared memory.
  * \param [out] mesh_buffer pointer to the raw mesh buffer
  * \param [out] m pointer to the mesh object
  *
@@ -96,7 +95,6 @@ class ScopedLogLevelChanger
  */
 int read_stl_mesh_shared(const std::string& file,
                          MPI_Comm global_comm,
-                         int allocatorID,
                          unsigned char*& mesh_buffer,
                          mint::Mesh*& m);
 #endif
diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index e63e9dca03..7e766a5d5d 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -102,7 +102,6 @@ static bool s_must_finalize_logger = false;
 static bool s_logger_is_initialized = false;
 
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
-static int s_allocator_id = INVALID_ALLOCATOR_ID;
 static unsigned char* s_shared_mesh_buffer = nullptr;
 #else
 static std::string s_shared_memory_requirements(
@@ -135,22 +134,8 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
   if(Parameters.use_shared_memory)
   {
-    if(s_allocator_id == INVALID_ALLOCATOR_ID)
-    {
-      // Make a shared memory allocator if we have not made it before. We'll reuse
-      // the allocator to allocate different buffers (1 at a time).
-      auto& rm = umpire::ResourceManager::getInstance();
-      auto traits {umpire::get_default_resource_traits("SHARED")};
-      traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
-      auto node_allocator {rm.makeResource("SHARED::node_allocator", traits)};
-      auto signed_distance_allocator {
-        rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>("signed_distance_allocator",
-                                                                    node_allocator)};
-      s_allocator_id = signed_distance_allocator.getId();
-    }
-
     rc =
-      internal::read_stl_mesh_shared(file, comm, s_allocator_id, s_shared_mesh_buffer, s_surface_mesh);
+      internal::read_stl_mesh_shared(file, comm, s_shared_mesh_buffer, s_surface_mesh);
   }
   else
   {

From ee8e9ba74f77908cb1ef6c126584f2b0c3de0ed7 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 15:05:29 -0700
Subject: [PATCH 18/24] make style

---
 src/axom/core/memory_management.cpp                | 7 +++----
 src/axom/quest/interface/internal/QuestHelpers.cpp | 3 +--
 src/axom/quest/interface/signed_distance.cpp       | 3 +--
 3 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/axom/core/memory_management.cpp b/src/axom/core/memory_management.cpp
index 29bd8975f6..2ad06d6fab 100644
--- a/src/axom/core/memory_management.cpp
+++ b/src/axom/core/memory_management.cpp
@@ -24,7 +24,7 @@ bool isSharedMemoryAllocator(int allocID)
     umpire::Allocator allocator = rm.getAllocator(allocID);
 
     isShared = allocator.getAllocationStrategy()->getTraits().resource ==
-                 umpire::MemoryResourceTraits::resource_type::shared;
+      umpire::MemoryResourceTraits::resource_type::shared;
   }
 #endif
   return isShared;
@@ -43,8 +43,7 @@ int getSharedMemoryAllocatorID()
     traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
     auto axom_node_allocator {rm.makeResource("SHARED::axom_node_allocator", traits)};
     auto axom_named_allocator {
-          rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>(allocatorName,
-                                                                      axom_node_allocator)};
+      rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>(allocatorName, axom_node_allocator)};
     allocator_id = axom_named_allocator.getId();
   }
   else
@@ -55,4 +54,4 @@ int getSharedMemoryAllocatorID()
   return allocator_id;
 }
 
-} // end namespace axom
+}  // end namespace axom
diff --git a/src/axom/quest/interface/internal/QuestHelpers.cpp b/src/axom/quest/interface/internal/QuestHelpers.cpp
index 557b6a3ca4..9a370ad4e6 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.cpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.cpp
@@ -244,8 +244,7 @@ int read_stl_mesh_shared(const std::string& file,
   double* y = nullptr;
   double* z = nullptr;
   axom::IndexType* conn = nullptr;
-  const size_t numBytes =
-    allocate_shared_buffer(mesh_metadata, x, y, z, conn, mesh_buffer);
+  const size_t numBytes = allocate_shared_buffer(mesh_metadata, x, y, z, conn, mesh_buffer);
   SLIC_ASSERT(x != nullptr);
   SLIC_ASSERT(y != nullptr);
   SLIC_ASSERT(z != nullptr);
diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index 7e766a5d5d..984806be59 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -134,8 +134,7 @@ int signed_distance_init(const std::string& file, MPI_Comm comm)
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
   if(Parameters.use_shared_memory)
   {
-    rc =
-      internal::read_stl_mesh_shared(file, comm, s_shared_mesh_buffer, s_surface_mesh);
+    rc = internal::read_stl_mesh_shared(file, comm, s_shared_mesh_buffer, s_surface_mesh);
   }
   else
   {

From d367dc793c0703a6abd1436b7e3837db52abf500 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 15:14:00 -0700
Subject: [PATCH 19/24] Moved some function declarations.

---
 src/axom/core/memory_management.hpp | 34 ++++++++++++++---------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/axom/core/memory_management.hpp b/src/axom/core/memory_management.hpp
index 59acc91238..8a9de5595b 100644
--- a/src/axom/core/memory_management.hpp
+++ b/src/axom/core/memory_management.hpp
@@ -144,6 +144,23 @@ inline int getAllocatorIDFromPointer(const void* ptr)
   return MALLOC_ALLOCATOR_ID;
 }
 
+/*!
+ * \brief Determines whether an allocator id is for shared memory.
+ *
+ * \param allocID An allocator id.
+ *
+ * \return True if the allocator id is for shared memory; false otherwise.
+ */
+bool isSharedMemoryAllocator(int allocID);
+
+/*!
+ * \brief Get the allocator ID for Axom's shared memory allocator.
+ *
+ * \return The allocator ID for Axom's shared memory allocator (if Axom is using Umpire),
+ *         or INVALID_ALLOCATOR_ID otherwise.
+ */
+int getSharedMemoryAllocatorID();
+
 /*!
  * \brief Allocates a chunk of memory of type T.
  *
@@ -542,23 +559,6 @@ inline bool isDeviceAllocator(int allocator_id)
 inline bool isDeviceAllocator(int AXOM_UNUSED_PARAM(allocator_id)) { return false; }
 #endif
 
-/*!
- * \brief Determines whether an allocator id is for shared memory.
- *
- * \param allocID An allocator id.
- *
- * \return True if the allocator id is for shared memory; false otherwise.
- */
-bool isSharedMemoryAllocator(int allocID);
-
-/*!
- * \brief Get the allocator ID for Axom's shared memory allocator.
- *
- * \return The allocator ID for Axom's shared memory allocator (if Axom is using Umpire),
- *         or INVALID_ALLOCATOR_ID otherwise.
- */
-int getSharedMemoryAllocatorID();
-
 }  // namespace axom
 
 #endif /* AXOM_MEMORYMANAGEMENT_HPP_ */

From 4ce036a014266a71c77c908800b676267d288d9e Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 15:22:54 -0700
Subject: [PATCH 20/24] Change how we get some Umpire includes

---
 src/axom/core/memory_management.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/axom/core/memory_management.cpp b/src/axom/core/memory_management.cpp
index 2ad06d6fab..d38177be5d 100644
--- a/src/axom/core/memory_management.cpp
+++ b/src/axom/core/memory_management.cpp
@@ -5,10 +5,12 @@
 
 #include "axom/core/memory_management.hpp"
 
-#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+#if defined(AXOM_USE_UMPIRE)
   #include "umpire/Umpire.hpp"
-  #include "umpire/strategy/NamedAllocationStrategy.hpp"
   #include "umpire/util/MemoryResourceTraits.hpp"
+  #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
+    #include "umpire/strategy/NamedAllocationStrategy.hpp"
+  #endif
 #endif
 
 namespace axom

From cad2b2b2a6c6285c047728f7fc4cdfa0720c2d5e Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 15:26:16 -0700
Subject: [PATCH 21/24] Removed some comments related to MPI windows.

---
 src/axom/quest/interface/internal/QuestHelpers.hpp | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/src/axom/quest/interface/internal/QuestHelpers.hpp b/src/axom/quest/interface/internal/QuestHelpers.hpp
index dcec418d43..a74190d295 100644
--- a/src/axom/quest/interface/internal/QuestHelpers.hpp
+++ b/src/axom/quest/interface/internal/QuestHelpers.hpp
@@ -84,14 +84,10 @@ class ScopedLogLevelChanger
  * \pre global_comm != MPI_COMM_NULL
  * \pre mesh_buffer == nullptr
  * \pre m == nullptr
- * \pre intra_node_comm == MPI_COMM_NULL
- * \pre shared_window == MPI_WIN_NULL
  *
  * \post m != nullptr
  * \post m->isExternal() == true
  * \post mesh_buffer != nullptr
- * \post intra_node_comm != MPI_COMM_NULL
- * \post shared_window != MPI_WIN_NULL
  */
 int read_stl_mesh_shared(const std::string& file,
                          MPI_Comm global_comm,

From c69d950f6bdfb7dcc9c2cc29ac694f2f5e0a37b5 Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 15:29:15 -0700
Subject: [PATCH 22/24] Removed some Umpire includes from signed_distance.

---
 src/axom/quest/interface/signed_distance.cpp | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/src/axom/quest/interface/signed_distance.cpp b/src/axom/quest/interface/signed_distance.cpp
index 984806be59..ac9a3fd31d 100644
--- a/src/axom/quest/interface/signed_distance.cpp
+++ b/src/axom/quest/interface/signed_distance.cpp
@@ -13,12 +13,6 @@
 
 #include "axom/slic/interface/slic.hpp"
 
-#if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
-  #include "umpire/Umpire.hpp"
-  #include "umpire/strategy/NamedAllocationStrategy.hpp"
-  #include "umpire/util/MemoryResourceTraits.hpp"
-#endif
-
 #ifdef AXOM_USE_MPI
   #include <mpi.h>
 #endif

From 7bef6e0b32965088718212bc262ec343ed128a3d Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 9 Sep 2025 16:45:06 -0700
Subject: [PATCH 23/24] Renamed axom shared allocator.

---
 src/axom/core/memory_management.cpp        | 6 +++---
 src/axom/core/tests/core_shared_memory.hpp | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/axom/core/memory_management.cpp b/src/axom/core/memory_management.cpp
index d38177be5d..8e22511ec3 100644
--- a/src/axom/core/memory_management.cpp
+++ b/src/axom/core/memory_management.cpp
@@ -36,7 +36,7 @@ int getSharedMemoryAllocatorID()
 {
   int allocator_id = INVALID_ALLOCATOR_ID;
 #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
-  const std::string allocatorName("axom_named_allocator");
+  const std::string allocatorName("axom_shared_allocator");
   auto& rm = umpire::ResourceManager::getInstance();
   if(!rm.isAllocator(allocatorName))
   {
@@ -44,9 +44,9 @@ int getSharedMemoryAllocatorID()
     auto traits {umpire::get_default_resource_traits("SHARED")};
     traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
     auto axom_node_allocator {rm.makeResource("SHARED::axom_node_allocator", traits)};
-    auto axom_named_allocator {
+    auto axom_shared_allocator {
       rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>(allocatorName, axom_node_allocator)};
-    allocator_id = axom_named_allocator.getId();
+    allocator_id = axom_shared_allocator.getId();
   }
   else
   {
diff --git a/src/axom/core/tests/core_shared_memory.hpp b/src/axom/core/tests/core_shared_memory.hpp
index 0819f48e29..532c19ad2e 100644
--- a/src/axom/core/tests/core_shared_memory.hpp
+++ b/src/axom/core/tests/core_shared_memory.hpp
@@ -22,10 +22,10 @@ TEST(core_shared_memory, shared_memory_allocator)
   int rank = 0;
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 
-  // Allocate shared memory
-  constexpr int sizes[] = {1024, 4096, 1000000};
+  const int sizes[] = {1024, 4096, 1000000};
   for(int si = 0; si < 3; si++)
   {
+    // Allocate shared memory
     const int N = sizes[si];
     int *buffer = axom::allocate<int>(N, axom::getSharedMemoryAllocatorID());
 

From 9e8d791130205244ad4cbb61fcd4f5154345961e Mon Sep 17 00:00:00 2001
From: Brad Whitlock <whitlock2@llnl.gov>
Date: Tue, 21 Oct 2025 11:23:17 -0700
Subject: [PATCH 24/24] Use UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE in the name
 of the requested shared memory allocator. Add cmake status message for value
 of UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE.

---
 src/axom/core/memory_management.cpp           |  6 ++++--
 src/axom/core/tests/core_shared_memory.hpp    |  2 ++
 .../thirdparty/SetupAxomThirdParty.cmake      | 20 ++++++++++++++++++-
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/axom/core/memory_management.cpp b/src/axom/core/memory_management.cpp
index 8e22511ec3..5b8c592bae 100644
--- a/src/axom/core/memory_management.cpp
+++ b/src/axom/core/memory_management.cpp
@@ -6,6 +6,7 @@
 #include "axom/core/memory_management.hpp"
 
 #if defined(AXOM_USE_UMPIRE)
+  #include "axom/fmt.hpp"
   #include "umpire/Umpire.hpp"
   #include "umpire/util/MemoryResourceTraits.hpp"
   #if defined(AXOM_USE_UMPIRE_SHARED_MEMORY)
@@ -41,9 +42,10 @@ int getSharedMemoryAllocatorID()
   if(!rm.isAllocator(allocatorName))
   {
     // Create the allocator
-    auto traits {umpire::get_default_resource_traits("SHARED")};
+    const auto name = axom::fmt::format("SHARED::{}", UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE);
+    auto traits {umpire::get_default_resource_traits(name)};
     traits.scope = umpire::MemoryResourceTraits::shared_scope::node;
-    auto axom_node_allocator {rm.makeResource("SHARED::axom_node_allocator", traits)};
+    auto axom_node_allocator {rm.makeResource(axom::fmt::format("{}::axom_node_allocator", name), traits)};
     auto axom_shared_allocator {
       rm.makeAllocator<umpire::strategy::NamedAllocationStrategy>(allocatorName, axom_node_allocator)};
     allocator_id = axom_shared_allocator.getId();
diff --git a/src/axom/core/tests/core_shared_memory.hpp b/src/axom/core/tests/core_shared_memory.hpp
index 532c19ad2e..4666c6cc9f 100644
--- a/src/axom/core/tests/core_shared_memory.hpp
+++ b/src/axom/core/tests/core_shared_memory.hpp
@@ -46,6 +46,8 @@ TEST(core_shared_memory, shared_memory_allocator)
       EXPECT_EQ(buffer[i], i);
     }
 
+    MPI_Barrier(MPI_COMM_WORLD);
+
     axom::deallocate(buffer);
   }
 }
diff --git a/src/cmake/thirdparty/SetupAxomThirdParty.cmake b/src/cmake/thirdparty/SetupAxomThirdParty.cmake
index 78d177c519..836d70d625 100644
--- a/src/cmake/thirdparty/SetupAxomThirdParty.cmake
+++ b/src/cmake/thirdparty/SetupAxomThirdParty.cmake
@@ -75,7 +75,25 @@ if (UMPIRE_DIR)
     else()
         set(AXOM_USE_UMPIRE_SHARED_MEMORY FALSE)
     endif()
-    message(STATUS "Umpire supports shared memory: ${AXOM_USE_UMPIRE_SHARED_MEMORY}")
+    message(STATUS "  Umpire supports shared memory: ${AXOM_USE_UMPIRE_SHARED_MEMORY}")
+
+    # If it looks like Umpire supports shared memory (and the header file exists)
+    # then print out the default type of shared memory.
+    set(UMPIRE_CONFIG_HPP "${UMPIRE_DIR}/include/umpire/config.hpp")
+    if(AXOM_USE_UMPIRE_SHARED_MEMORY AND EXISTS "${UMPIRE_CONFIG_HPP}")
+        file(READ "${UMPIRE_CONFIG_HPP}" UMPIRE_CONFIG_HPP_CONTENTS)
+        # Try to match: #define UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE <value>
+        string(REGEX MATCH "#define[ \t]+UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE[ \t]+([^\n\r ]+)" UMPIRE_MACRO_LINE "${UMPIRE_CONFIG_HPP_CONTENTS}")
+        if(UMPIRE_MACRO_LINE)
+            # Extract just the value (the first capture group)
+            string(REGEX REPLACE ".*#define[ \t]+UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE[ \t]+\"([^\"]*)\".*" "\\1" UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE "${UMPIRE_MACRO_LINE}")
+            message(STATUS "  UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE: ${UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE}")
+        else()
+            message(STATUS "  UMPIRE_DEFAULT_SHARED_MEMORY_RESOURCE is not defined in ${UMPIRE_CONFIG_HPP}")
+        endif()
+    else()
+        message(WARNING "  Could not find ${UMPIRE_CONFIG_HPP}")
+    endif()
 else()
     message(STATUS "Umpire support is OFF")
     set(UMPIRE_FOUND FALSE)