diff --git a/CHANGELOG.md b/CHANGELOG.md
index 707dcf502..4e892bf9f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,9 @@ and this project aspires to adhere to [Semantic Versioning](https://semver.org/s
 - Added a `topologies` option to the relay extract. This allows you to select which topologies are saved. This option can be used with the existing `fields` option, the result is the union of the selected topologies and fields.
 - Added `near_plane` and `far_plane` to the camera details provided in Ascent::info()
 
+### Fixed
+- Resolved a few cases where MPI_COMM_WORLD was used instead instead of the selected MPI communicator.
+
 ## [0.9.3] - Released 2024-05-11
 ### Preferred dependency versions for ascent@0.9.3
 - conduit@0.9.1
diff --git a/src/libs/apcomp/compositor.cpp b/src/libs/apcomp/compositor.cpp
index 205b0ca36..039feb42c 100644
--- a/src/libs/apcomp/compositor.cpp
+++ b/src/libs/apcomp/compositor.cpp
@@ -222,8 +222,7 @@ Compositor::CompositeZBufferSurface()
   // nothing to do here in serial. Images were composited as
   // they were added to the compositor
 #ifdef APCOMP_PARALLEL
-  apcompdiy::mpi::communicator diy_comm;
-  diy_comm = apcompdiy::mpi::communicator(MPI_Comm_f2c(mpi_comm()));
+  apcompdiy::mpi::communicator diy_comm(MPI_Comm_f2c(mpi_comm()));
 
   assert(m_images.size() == 1);
   RadixKCompositor compositor;
@@ -243,8 +242,7 @@ Compositor::CompositeVisOrder()
 {
 
 #ifdef APCOMP_PARALLEL
-  apcompdiy::mpi::communicator diy_comm;
-  diy_comm = apcompdiy::mpi::communicator(MPI_Comm_f2c(mpi_comm()));
+  apcompdiy::mpi::communicator diy_comm(MPI_Comm_f2c(mpi_comm()));
 
   assert(m_images.size() != 0);
   DirectSendCompositor compositor;
diff --git a/src/libs/apcomp/internal/apcomp_diy_partial_redistribute.hpp b/src/libs/apcomp/internal/apcomp_diy_partial_redistribute.hpp
index e72136c2d..1e9df7179 100644
--- a/src/libs/apcomp/internal/apcomp_diy_partial_redistribute.hpp
+++ b/src/libs/apcomp/internal/apcomp_diy_partial_redistribute.hpp
@@ -26,9 +26,12 @@ template<typename BlockType>
 struct Redistribute
 {
   const apcompdiy::RegularDecomposer<apcompdiy::DiscreteBounds> &m_decomposer;
+  MPI_Comm &m_comm;
 
-  Redistribute(const apcompdiy::RegularDecomposer<apcompdiy::DiscreteBounds> &decomposer)
-    : m_decomposer(decomposer)
+  Redistribute(const apcompdiy::RegularDecomposer<apcompdiy::DiscreteBounds> &decomposer,
+               MPI_Comm &comm)
+    : m_decomposer(decomposer),
+      m_comm(comm)
   {}
 
   void operator()(void *v_block, const apcompdiy::ReduceProxy &proxy) const
@@ -81,7 +84,7 @@ struct Redistribute
       } // for
 
     } // else
-    MPI_Barrier(MPI_COMM_WORLD); //HACK
+    MPI_Barrier(m_comm); //HACK
   } // operator
 };
 
@@ -113,7 +116,7 @@ void redistribute_detail(std::vector<typename AddBlockType::PartialType> &partia
 
   apcompdiy::RegularDecomposer<apcompdiy::DiscreteBounds> decomposer(dims, global_bounds, num_blocks);
   decomposer.decompose(world.rank(), assigner, create);
-  apcompdiy::all_to_all(master, assigner, Redistribute<Block>(decomposer), magic_k);
+  apcompdiy::all_to_all(master, assigner, Redistribute<Block>(decomposer,comm), magic_k);
 }
 
 //
diff --git a/src/libs/apcomp/internal/diy/include/diy/mpi/communicator.hpp b/src/libs/apcomp/internal/diy/include/diy/mpi/communicator.hpp
index c1999e314..ee76959e1 100644
--- a/src/libs/apcomp/internal/diy/include/diy/mpi/communicator.hpp
+++ b/src/libs/apcomp/internal/diy/include/diy/mpi/communicator.hpp
@@ -8,8 +8,11 @@ namespace mpi
   class communicator
   {
     public:
+                inline 
+                communicator();
+
                 inline
-                communicator(MPI_Comm comm = MPI_COMM_WORLD, bool owner = false);
+                communicator(MPI_Comm comm, bool owner = false);
 
                 ~communicator()                     { destroy(); }
 
@@ -97,6 +100,14 @@ namespace mpi
 }
 }
 
+apcompdiy::mpi::communicator::
+communicator():
+    comm_(MPI_COMM_NULL), rank_(0), size_(1), owner_(false)
+{
+  // empty
+}
+
+
 apcompdiy::mpi::communicator::
 communicator(MPI_Comm comm, bool owner):
     comm_(comm), rank_(0), size_(1), owner_(owner)
diff --git a/src/libs/ascent/runtimes/flow_filters/ascent_runtime_rover_filters.cpp b/src/libs/ascent/runtimes/flow_filters/ascent_runtime_rover_filters.cpp
index 94f90c42e..0d91b68a6 100644
--- a/src/libs/ascent/runtimes/flow_filters/ascent_runtime_rover_filters.cpp
+++ b/src/libs/ascent/runtimes/flow_filters/ascent_runtime_rover_filters.cpp
@@ -40,6 +40,7 @@
 
 #if defined(ASCENT_VTKM_ENABLED)
 #include <rover.hpp>
+#include <rover/utils/rover_logging.hpp>
 #include <ray_generators/camera_generator.hpp>
 #include <vtkh/vtkh.hpp>
 #include <vtkh/DataSet.hpp>
@@ -212,6 +213,9 @@ RoverXRay::execute()
     Rover tracer;
 #ifdef ASCENT_MPI_ENABLED
     int comm_id = flow::Workspace::default_mpi_comm();
+    rover::Logger::get_instance()->set_mpi_comm_id(comm_id);
+    /// these use different styles of naming functions ....
+    rover::DataLogger::GetInstance()->set_mpi_comm_id(comm_id);
     tracer.set_mpi_comm_handle(comm_id);
 #endif
 
diff --git a/src/libs/ascent/runtimes/flow_filters/ascent_runtime_vtkh_filters.cpp b/src/libs/ascent/runtimes/flow_filters/ascent_runtime_vtkh_filters.cpp
index cf45984a5..affd30249 100644
--- a/src/libs/ascent/runtimes/flow_filters/ascent_runtime_vtkh_filters.cpp
+++ b/src/libs/ascent/runtimes/flow_filters/ascent_runtime_vtkh_filters.cpp
@@ -5178,7 +5178,7 @@ VTKHVTKFileExtract::execute()
         Node n_recv;
         conduit::relay::mpi::all_gather_using_schema(n_local_domain_ids,
                                                      n_recv,
-                                                     MPI_COMM_WORLD);
+                                                     mpi_comm);
         n_global_domain_ids.set(DataType::index_t(num_global_domains));
         n_global_domain_ids.print();
         index_t_array global_vals = n_global_domain_ids.value();
diff --git a/src/libs/rover/utils/rover_logging.cpp b/src/libs/rover/utils/rover_logging.cpp
index f189b8556..11c4d5673 100644
--- a/src/libs/rover/utils/rover_logging.cpp
+++ b/src/libs/rover/utils/rover_logging.cpp
@@ -23,7 +23,7 @@ Logger::Logger()
   log_name<<"rover";
 #ifdef ROVER_PARALLEL
   int rank;
-  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Comm_rank(MPI_Comm_f2c(get_mpi_comm_id()), &rank);
   log_name<<"_"<<rank;
 #endif
   log_name<<".log";
@@ -45,6 +45,20 @@ Logger* Logger::get_instance()
   return m_instance;
 }
 
+void
+Logger::set_mpi_comm_id(int comm_id)
+{
+  m_mpi_comm_id = comm_id;
+}
+
+int
+Logger::get_mpi_comm_id()
+{
+  return m_mpi_comm_id;
+}
+  
+  
+
 std::ofstream& Logger::get_stream()
 {
   return m_stream;
@@ -75,6 +89,18 @@ DataLogger::~DataLogger()
   Stream.str("");
 }
 
+void
+DataLogger::set_mpi_comm_id(int comm_id)
+{
+  m_mpi_comm_id = comm_id;
+}
+
+int
+DataLogger::get_mpi_comm_id()
+{
+  return m_mpi_comm_id;
+}
+
 DataLogger*
 DataLogger::GetInstance()
 {
@@ -99,7 +125,7 @@ DataLogger::WriteLog()
   log_name<<"rover_data";
 #ifdef ROVER_PARALLEL
   int rank;
-  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Comm_rank(MPI_Comm_f2c(get_mpi_comm_id()), &rank);
   log_name<<"_"<<rank;
 #endif
   log_name<<".log";
diff --git a/src/libs/rover/utils/rover_logging.hpp b/src/libs/rover/utils/rover_logging.hpp
index 3a84807ab..01f8aac59 100644
--- a/src/libs/rover/utils/rover_logging.hpp
+++ b/src/libs/rover/utils/rover_logging.hpp
@@ -10,28 +10,34 @@
 #include <fstream>
 #include <stack>
 #include <sstream>
+#include <rover_exports.h>
 
 namespace rover {
 
-class Logger
+class ROVER_API Logger
 {
 public:
   ~Logger();
   static Logger *get_instance();
+  void set_mpi_comm_id(int comm_id);
+  int  get_mpi_comm_id();
   void write(const int level, const std::string &message, const char *file, int line);
   std::ofstream & get_stream();
 protected:
   Logger();
   Logger(Logger const &);
   std::ofstream m_stream;
+  int m_mpi_comm_id;
   static class Logger* m_instance;
 };
 
-class DataLogger
+class ROVER_API DataLogger
 {
 public:
   ~DataLogger();
   static DataLogger *GetInstance();
+  void set_mpi_comm_id(int comm_id);
+  int  get_mpi_comm_id();
   void OpenLogEntry(const std::string &entryName);
   void CloseLogEntry(const double &entryTime);
 
@@ -49,6 +55,7 @@ class DataLogger
   std::stringstream Stream;
   static class DataLogger* Instance;
   std::stack<std::string> Entries;
+  int m_mpi_comm_id;
 };
 
 #ifdef ROVER_ENABLE_LOGGING
diff --git a/src/libs/rover/utils/vtk_dataset_reader.cpp b/src/libs/rover/utils/vtk_dataset_reader.cpp
index 032645ce6..07792b1af 100644
--- a/src/libs/rover/utils/vtk_dataset_reader.cpp
+++ b/src/libs/rover/utils/vtk_dataset_reader.cpp
@@ -4,6 +4,7 @@
 // other details. No copyright assignment is required to contribute to Ascent.
 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//
 
+#include <utils/rover_logging.hpp>
 #include <utils/vtk_dataset_reader.hpp>
 #include <vtkm/io/VTKDataSetReader.h>
 #include <iostream>
@@ -98,10 +99,10 @@ MultiDomainVTKReader::read_file(const std::string &directory, const std::string
      //
      // figure out which data sets to read
      //
-     int rank;
-     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
-     int num_ranks;
-     MPI_Comm_size(MPI_COMM_WORLD, &num_ranks);
+     int rank, num_ranks;
+     MPI_Comm comm = MPI_Comm_f2c(Logger::get_instance()->get_mpi_comm_id());
+     MPI_Comm_rank(comm, &rank);
+     MPI_Comm_size(comm, &num_ranks);
      if(rank == 0)
      {
         std::cout<<"Num ranks "<<num_ranks<<"\n";
diff --git a/src/libs/vtkh/StatisticsDB.hpp b/src/libs/vtkh/StatisticsDB.hpp
index 3f10792d0..3d901ac8f 100644
--- a/src/libs/vtkh/StatisticsDB.hpp
+++ b/src/libs/vtkh/StatisticsDB.hpp
@@ -251,9 +251,10 @@ class VTKH_API StatisticsDB
             return;
 
 #ifdef VTKH_PARALLEL
+        MPI_Comm mpi_comm = MPI_Comm_f2c(vtkh::GetMPICommHandle());
         int rank, nProcs;
-        MPI_Comm_size(MPI_COMM_WORLD, &nProcs);
-        MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+        MPI_Comm_size(mpi_comm, &nProcs);
+        MPI_Comm_rank(mpi_comm, &rank);
 
         int sz = 0;
 
@@ -275,7 +276,7 @@ class VTKH_API StatisticsDB
                 {
                     std::vector<float>tmp(nProcs,0.0);
                     tmp[rank] = vals[i];
-                    MPI_Reduce(&tmp[0], &res[0], nProcs, MPI_FLOAT, MPI_SUM, 0, MPI_COMM_WORLD);
+                    MPI_Reduce(&tmp[0], &res[0], nProcs, MPI_FLOAT, MPI_SUM, 0, mpi_comm);
                 }
                 if (rank == 0)
                     timerStats[it->first] = statValue<float>(res);
@@ -300,7 +301,7 @@ class VTKH_API StatisticsDB
                 {
                     std::vector<unsigned long> tmp(nProcs,0);
                     tmp[rank] = vals[i];
-                    MPI_Reduce(&tmp[0], &res[0], nProcs, MPI_UNSIGNED_LONG, MPI_SUM, 0, MPI_COMM_WORLD);
+                    MPI_Reduce(&tmp[0], &res[0], nProcs, MPI_UNSIGNED_LONG, MPI_SUM, 0, mpi_comm);
                 }
                 if (rank == 0)
                     counterStats[it->first] = statValue<unsigned long>(res);
@@ -334,9 +335,9 @@ class VTKH_API StatisticsDB
 
             float allMin, allMax;
             int allMaxSz;
-            MPI_Allreduce(&myMin, &allMin, 1, MPI_FLOAT, MPI_MIN, MPI_COMM_WORLD);
-            MPI_Allreduce(&myMax, &allMax, 1, MPI_FLOAT, MPI_MAX, MPI_COMM_WORLD);
-            MPI_Allreduce(&myMaxSz, &allMaxSz, 1, MPI_INT, MPI_MAX, MPI_COMM_WORLD);
+            MPI_Allreduce(&myMin, &allMin, 1, MPI_FLOAT, MPI_MIN, mpi_comm);
+            MPI_Allreduce(&myMax, &allMax, 1, MPI_FLOAT, MPI_MAX, mpi_comm);
+            MPI_Allreduce(&myMaxSz, &allMaxSz, 1, MPI_INT, MPI_MAX, mpi_comm);
 
             int buffSz = allMaxSz*2 + 1, tag = 0;
             for (it = events.begin(); it != events.end(); it++)
@@ -354,7 +355,7 @@ class VTKH_API StatisticsDB
                     for (int i = 1; i < nProcs; i++)
                     {
                         MPI_Status status;
-                        MPI_Recv(&buff[0], buffSz, MPI_FLOAT, i, tag, MPI_COMM_WORLD, &status);
+                        MPI_Recv(&buff[0], buffSz, MPI_FLOAT, i, tag, mpi_comm, &status);
                         int n = int(buff[0]);
                         for (int j = 0; j < n; j+=2)
                             eventStats[i][it->first].history.push_back(std::make_pair(buff[1+j], buff[1+j+1]));
@@ -373,7 +374,7 @@ class VTKH_API StatisticsDB
                         evData[1+j*2+0] = it->second.history[j].first;
                         evData[1+j*2+1] = it->second.history[j].second;
                     }
-                    MPI_Send(&evData[0], buffSz, MPI_FLOAT, 0, tag, MPI_COMM_WORLD);
+                    MPI_Send(&evData[0], buffSz, MPI_FLOAT, 0, tag, mpi_comm);
                 }
             }
         }
diff --git a/src/libs/vtkh/compositing/Compositor.cpp b/src/libs/vtkh/compositing/Compositor.cpp
index 93971f705..a750b574c 100644
--- a/src/libs/vtkh/compositing/Compositor.cpp
+++ b/src/libs/vtkh/compositing/Compositor.cpp
@@ -202,8 +202,7 @@ Compositor::CompositeZBufferSurface()
   // nothing to do here in serial. Images were composited as
   // they were added to the compositor
 #ifdef VTKH_PARALLEL
-  vtkhdiy::mpi::communicator diy_comm;
-  diy_comm = vtkhdiy::mpi::communicator(MPI_Comm_f2c(GetMPICommHandle()));
+  vtkhdiy::mpi::communicator diy_comm(MPI_Comm_f2c(GetMPICommHandle()));
 
   assert(m_images.size() == 1);
   RadixKCompositor compositor;
@@ -223,8 +222,7 @@ Compositor::CompositeVisOrder()
 {
 
 #ifdef VTKH_PARALLEL
-  vtkhdiy::mpi::communicator diy_comm;
-  diy_comm = vtkhdiy::mpi::communicator(MPI_Comm_f2c(GetMPICommHandle()));
+  vtkhdiy::mpi::communicator diy_comm(MPI_Comm_f2c(GetMPICommHandle()));
 
   assert(m_images.size() != 0);
   DirectSendCompositor compositor;
diff --git a/src/libs/vtkh/compositing/PayloadCompositor.cpp b/src/libs/vtkh/compositing/PayloadCompositor.cpp
index 38a3ac60b..3f7a341ee 100644
--- a/src/libs/vtkh/compositing/PayloadCompositor.cpp
+++ b/src/libs/vtkh/compositing/PayloadCompositor.cpp
@@ -51,8 +51,7 @@ PayloadCompositor::Composite()
   // nothing to do here in serial. Images were composited as
   // they were added to the compositor
 #ifdef VTKH_PARALLEL
-  vtkhdiy::mpi::communicator diy_comm;
-  diy_comm = vtkhdiy::mpi::communicator(MPI_Comm_f2c(GetMPICommHandle()));
+  vtkhdiy::mpi::communicator diy_comm(MPI_Comm_f2c(GetMPICommHandle()));
 
   assert(m_images.size() == 1);
   RadixKCompositor compositor;
diff --git a/src/libs/vtkh/compositing/internal/diy/include/diy/mpi/communicator.hpp b/src/libs/vtkh/compositing/internal/diy/include/diy/mpi/communicator.hpp
index f1d9a1e19..a2ad9be08 100644
--- a/src/libs/vtkh/compositing/internal/diy/include/diy/mpi/communicator.hpp
+++ b/src/libs/vtkh/compositing/internal/diy/include/diy/mpi/communicator.hpp
@@ -8,7 +8,7 @@ namespace mpi
   class communicator
   {
     public:
-                communicator(MPI_Comm comm = MPI_COMM_WORLD):
+                communicator(MPI_Comm comm):
                   comm_(comm)                       { MPI_Comm_rank(comm_, &rank_); MPI_Comm_size(comm_, &size_); }
 
       int       rank() const                        { return rank_; }
diff --git a/src/libs/vtkh/compositing/vtkh_diy_partial_redistribute.hpp b/src/libs/vtkh/compositing/vtkh_diy_partial_redistribute.hpp
index fc4614ff1..a0a73623d 100644
--- a/src/libs/vtkh/compositing/vtkh_diy_partial_redistribute.hpp
+++ b/src/libs/vtkh/compositing/vtkh_diy_partial_redistribute.hpp
@@ -59,9 +59,12 @@ template<typename BlockType>
 struct Redistribute
 {
   const vtkhdiy::RegularDecomposer<vtkhdiy::DiscreteBounds> &m_decomposer;
+  MPI_Comm &m_comm;
 
-  Redistribute(const vtkhdiy::RegularDecomposer<vtkhdiy::DiscreteBounds> &decomposer)
-    : m_decomposer(decomposer)
+  Redistribute(const vtkhdiy::RegularDecomposer<vtkhdiy::DiscreteBounds> &decomposer,
+               MPI_Comm &comm)
+    : m_decomposer(decomposer),
+      m_comm(comm)
   {}
 
   void operator()(void *v_block, const vtkhdiy::ReduceProxy &proxy) const
@@ -113,7 +116,7 @@ struct Redistribute
       } // for
 
     } // else
-    MPI_Barrier(MPI_COMM_WORLD); //HACK
+    MPI_Barrier(m_comm); //HACK
   } // operator
 };
 
@@ -145,7 +148,7 @@ void redistribute_detail(std::vector<typename AddBlockType::PartialType> &partia
   const int dims = 1;
   vtkhdiy::RegularDecomposer<vtkhdiy::DiscreteBounds> decomposer(dims, global_bounds, num_blocks);
   decomposer.decompose(world.rank(), assigner, create);
-  vtkhdiy::all_to_all(master, assigner, Redistribute<Block>(decomposer), magic_k);
+  vtkhdiy::all_to_all(master, assigner, Redistribute<Block>(decomposer,comm), magic_k);
 }
 
 //
diff --git a/src/libs/vtkh/filters/Slice.cpp b/src/libs/vtkh/filters/Slice.cpp
index 97c545209..93be63004 100644
--- a/src/libs/vtkh/filters/Slice.cpp
+++ b/src/libs/vtkh/filters/Slice.cpp
@@ -644,7 +644,7 @@ AutoSliceLevels::DoExecute()
   float datafield_min = 0.;
 
 #if ASCENT_MPI_ENABLED
-
+  MPI_Comm mpi_comm = MPI_Comm_f2c(vtkh::GetMPICommHandle());
   float local_datafield_max = 0.;
   float local_datafield_min = 0.;
 
@@ -653,8 +653,8 @@ AutoSliceLevels::DoExecute()
     local_datafield_max = (float)*max_element(field_data.begin(),field_data.end());
     local_datafield_min = (float)*min_element(field_data.begin(),field_data.end());
   }
-  MPI_Reduce(&local_datafield_max, &datafield_max, 1, MPI_FLOAT, MPI_MAX, 0, MPI_COMM_WORLD);
-  MPI_Reduce(&local_datafield_min, &datafield_min, 1, MPI_FLOAT, MPI_MIN, 0, MPI_COMM_WORLD);
+  MPI_Reduce(&local_datafield_max, &datafield_max, 1, MPI_FLOAT, MPI_MAX, 0, mpi_comm);
+  MPI_Reduce(&local_datafield_min, &datafield_min, 1, MPI_FLOAT, MPI_MIN, 0, mpi_comm);
 
 #else
 
diff --git a/src/libs/vtkh/filters/UniformGrid.cpp b/src/libs/vtkh/filters/UniformGrid.cpp
index b9b13b09a..16211cf1f 100644
--- a/src/libs/vtkh/filters/UniformGrid.cpp
+++ b/src/libs/vtkh/filters/UniformGrid.cpp
@@ -216,8 +216,8 @@ class GlobalReduceField
         }
       }
 
-      MPI_Reduce(l_mask.data(), g_mask.data(), num_points, MPI_INT, MPI_LAND, 0, MPI_COMM_WORLD);
-      MPI_Reduce(l_valid.data(), g_valid.data(), num_points, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
+      MPI_Reduce(l_mask.data(), g_mask.data(), num_points, MPI_INT, MPI_LAND, 0, mpi_comm);
+      MPI_Reduce(l_valid.data(), g_valid.data(), num_points, MPI_INT, MPI_SUM, 0, mpi_comm);
 
       ////send to root process
       if(uah_field.CanConvert<scalarI>())
@@ -235,7 +235,7 @@ class GlobalReduceField
           }
         }
 
-        MPI_Reduce(local_field, global_field.data(), num_points, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
+        MPI_Reduce(local_field, global_field.data(), num_points, MPI_INT, MPI_SUM, 0, mpi_comm);
 
         if(par_rank == 0)
         {
@@ -277,7 +277,7 @@ class GlobalReduceField
             ah_field.WritePortal().Set(i,0);
         }
 
-        MPI_Reduce(local_field, global_field.data(), num_points, MPI_FLOAT, MPI_SUM, 0, MPI_COMM_WORLD);
+        MPI_Reduce(local_field, global_field.data(), num_points, MPI_FLOAT, MPI_SUM, 0, mpi_comm);
 
         if(par_rank == 0)
         {
@@ -317,7 +317,7 @@ class GlobalReduceField
         }
         double * local_field = GetVTKMPointer(ah_field);
         std::vector<double> global_field(num_points,0);
-        MPI_Reduce(local_field, global_field.data(), num_points, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
+        MPI_Reduce(local_field, global_field.data(), num_points, MPI_DOUBLE, MPI_SUM, 0, mpi_comm);
 
         if(par_rank == 0)
         {
@@ -365,8 +365,8 @@ class GlobalReduceField
           local_y_points[i] = ah_field.ReadPortal().Get(i)[1];
         }
 
-        MPI_Reduce(local_x_points.data(), global_x_points.data(), num_points, MPI_FLOAT, MPI_SUM, 0, MPI_COMM_WORLD);
-        MPI_Reduce(local_y_points.data(), global_y_points.data(), num_points, MPI_FLOAT, MPI_SUM, 0, MPI_COMM_WORLD);
+        MPI_Reduce(local_x_points.data(), global_x_points.data(), num_points, MPI_FLOAT, MPI_SUM, 0, mpi_comm);
+        MPI_Reduce(local_y_points.data(), global_y_points.data(), num_points, MPI_FLOAT, MPI_SUM, 0, mpi_comm);
 
         if(par_rank == 0)
         {
diff --git a/src/libs/vtkh/filters/avtParICAlgorithm.hpp b/src/libs/vtkh/filters/avtParICAlgorithm.hpp
index a970dd59e..bae837b9e 100644
--- a/src/libs/vtkh/filters/avtParICAlgorithm.hpp
+++ b/src/libs/vtkh/filters/avtParICAlgorithm.hpp
@@ -83,6 +83,7 @@ class avtParICAlgorithm
     typedef std::map<RequestTagPair, unsigned char *>::iterator bufferIterator;
     typedef std::map<RankIdPair, std::list<unsigned char *>>::iterator packetIterator;
 
+    MPI_Comm  comm;
     int rank, nProcs;
 
     std::map<RequestTagPair, unsigned char *> sendBuffers, recvBuffers;
diff --git a/src/libs/vtkh/filters/avtParICAlgorithm.hxx b/src/libs/vtkh/filters/avtParICAlgorithm.hxx
index d3bff5d11..9257d395a 100644
--- a/src/libs/vtkh/filters/avtParICAlgorithm.hxx
+++ b/src/libs/vtkh/filters/avtParICAlgorithm.hxx
@@ -2,15 +2,15 @@
 #include <string.h>
 #include "MemStream.h"
 #include <vtkh/filters/DebugMeowMeow.hpp>
-//#include "avtParICAlgorithm.h"
 
 using namespace std;
 
-avtParICAlgorithm::avtParICAlgorithm(MPI_Comm comm)
+avtParICAlgorithm::avtParICAlgorithm(MPI_Comm _comm):
+: comm(_comm),
+  msgID(0)
 {
-    MPI_Comm_size(comm, &nProcs);
-    MPI_Comm_rank(comm, &rank);
-    msgID = 0;
+    MPI_Comm_size(transaction_safe_dynamic, &nProcs);
+    MPI_Comm_rank(_comm, &rank);
 }
 
 void
@@ -92,9 +92,9 @@ avtParICAlgorithm::PostRecv(int tag, int sz, int src)
 
     MPI_Request req;
     if (src == -1)
-        MPI_Irecv(buff, sz, MPI_BYTE, MPI_ANY_SOURCE, tag, MPI_COMM_WORLD, &req);
+        MPI_Irecv(buff, sz, MPI_BYTE, MPI_ANY_SOURCE, tag, comm, &req);
     else
-        MPI_Irecv(buff, sz, MPI_BYTE, src, tag, MPI_COMM_WORLD, &req);
+        MPI_Irecv(buff, sz, MPI_BYTE, src, tag, comm, &req);
 
     RequestTagPair entry(req, tag);
     recvBuffers[entry] = buff;
@@ -220,7 +220,7 @@ avtParICAlgorithm::SendData(int dst, int tag, MemStream *buff)
         memcpy(&header, bufferList[i], sizeof(header));
         MPI_Request req;
         int err = MPI_Isend(bufferList[i], header.packetSz, MPI_BYTE, dst,
-                            tag, MPI_COMM_WORLD, &req);
+                            tag, comm, &req);
         if (err != MPI_SUCCESS)
         {
             cerr << "Err with MPI_Isend in PARIC algorithm" << endl;