diff --git a/.gitignore b/.gitignore
index 59f3cd1142..5b5dddbd8b 100755
--- a/.gitignore
+++ b/.gitignore
@@ -85,6 +85,7 @@ Backends/installed/**
 ScannerBit/downloaded/**
 ScannerBit/installed/**
 ScannerBit/lib/plugin_libraries.list
+downloaded_tarball_paths.txt
 
 # GUM files
 *.mug
diff --git a/Printers/include/gambit/Printers/printers/hdf5printer.hpp b/Printers/include/gambit/Printers/printers/hdf5printer.hpp
index f6acf1b267..613b2761ea 100644
--- a/Printers/include/gambit/Printers/printers/hdf5printer.hpp
+++ b/Printers/include/gambit/Printers/printers/hdf5printer.hpp
@@ -332,17 +332,20 @@ namespace Gambit
         std::string group;     // HDF5 group location to store datasets
         std::string metadata_group; // HDF5 group location to store metadata
 
-        // Handles for HDF5 files and groups containing the datasets
-        hid_t file_id;
-        hid_t group_id;
-        hid_t RA_group_id;
-        hid_t metadata_id;
+        // Handles for HDF5 files and groups containing the datasets.
+        // Only the primary printer's constructor assigns the file/group 
+        // handles (file_id, group_id, RA_group_id, metadata_id). Aux instances
+        // inherit the *_location_id values from the primary.
+        hid_t file_id = -1;
+        hid_t group_id = -1;
+        hid_t RA_group_id = -1;
+        hid_t metadata_id = -1;
 
         // Handle to a location in a HDF5 to which the datasets will be written
         // i.e. a file or a group.
-        hid_t location_id;
-        hid_t RA_location_id;
-        hid_t metadata_location_id;
+        hid_t location_id = -1;
+        hid_t RA_location_id = -1;
+        hid_t metadata_location_id = -1;
 
         /// Pointer to the primary printer object
         // (if this is an auxilliary printer, else it is "this" //NULL)
@@ -543,10 +546,13 @@ namespace Gambit
 
         // Force increment the buffer to "catch it up" to the current sync
         // position, in case it has been created "late".
-        // We subtract one because another increment will happen after
-        // the print statement (that triggered the creation of the new
-        // buffer) completes.
-        if(synchronised) it->second.fast_forward(printer->get_sync_pos()-1);
+        if (printer->get_sync_pos() > 0)  // if 0, nothing to catch up to
+        {
+          // We subtract one because another increment will happen after
+          // the print statement (that triggered the creation of the new
+          // buffer) completes.
+          if(synchronised) it->second.fast_forward(printer->get_sync_pos()-1);
+        }        
       }
 
       if( it == local_buffers.end() )
diff --git a/Printers/include/gambit/Printers/printers/hdf5printer/DataSetInterfaceBase.hpp b/Printers/include/gambit/Printers/printers/hdf5printer/DataSetInterfaceBase.hpp
index 17d4b01521..8e55d47338 100644
--- a/Printers/include/gambit/Printers/printers/hdf5printer/DataSetInterfaceBase.hpp
+++ b/Printers/include/gambit/Printers/printers/hdf5printer/DataSetInterfaceBase.hpp
@@ -184,23 +184,20 @@ namespace Gambit {
         for(std::size_t i=0; i<DSETRANK; i++) { record_dims[i] = rdims[i]; }
       }
 
-      /// Do cleanup (close dataset)
+      /// Destructor.
+      /// Deliberately does NOT close the underlying HDF5 dataset.
+      ///
+      /// DataSetInterfaceBase (and its derived classes) are stored by value
+      /// and assigned-from-temporary in several places. In such cases a 
+      /// temporary is constructed, then copy-/move-assigned into a member or 
+      /// container slot, then destroyed. Closing here in the destructor would 
+      /// invalidate the handle held by the surviving copy. The actual close 
+      /// therefore lives in the explicit closeDataSet() method below, used by
+      /// VertexBufferNumeric1D_HDF5::finalise() during the printer's
+      /// finalise() pass.
       template<class T, std::size_t RR, std::size_t CL>
       DataSetInterfaceBase<T,RR,CL>::~DataSetInterfaceBase()
       {
-         // TODO: Having problems with copied objects sharing dataset identifiers, and closing datasets prematurely on each other.
-         // To fix, will probably need to have a fancy copy constructor or something. Or wrap datasets in an
-         // object which itself has a fancy copy constructor. For now, just leave dataset resources lying around,
-         // probably won't cause any issues.
-         // Or could explicity tell interface to close datasets before the objects are destroyed.
-         //if(this->dset_id>=0)
-         //{
-         //  herr_t status = H5Dclose(this->dset_id);
-         //  if(status<0)
-         //  {
-         //     logger() << LogTags::printers << LogTags::err <<LogTags::repeat_to_cerr<< LOCAL_INFO << ": Error destructing DataSetInterfaceBase! Failed to close wrapped dataset! (H5Dclose failed). No exception thrown because this will behave badly when throw from a destructor. (dataset name: "<<myname<<")"<<EOM;
-         //  }
-         //}
       }
 
       /// Release resources associated with the underlying dataset
diff --git a/Printers/include/gambit/Printers/printers/hdf5printer/VertexBufferNumeric1D_HDF5.hpp b/Printers/include/gambit/Printers/printers/hdf5printer/VertexBufferNumeric1D_HDF5.hpp
index 0f8aa20f0f..924911f832 100644
--- a/Printers/include/gambit/Printers/printers/hdf5printer/VertexBufferNumeric1D_HDF5.hpp
+++ b/Printers/include/gambit/Printers/printers/hdf5printer/VertexBufferNumeric1D_HDF5.hpp
@@ -290,16 +290,24 @@ namespace Gambit {
         }
       }
  
-      /// Destructor
+      /// Destructor.
+      /// Deliberately does NOT flush the buffer to disk.
+      ///
+      /// Buffer objects of this type are stored by value (in the
+      /// std::map<VBIDpair, BuffType> inside H5P_LocalBufferManager) and
+      /// are populated via the assign-from-temporary pattern at
+      /// H5P_LocalBufferManager::get_buffer, so each buffer object's
+      /// destructor runs at least once on a temporary that shares state
+      /// (HDF5 dataset handles, sync counters) with the surviving
+      /// container slot. Triggering write_to_disk() / RA_write_to_disk()
+      /// here would therefore either double-write or write through stale
+      /// state, depending on which copy is being destroyed. End-of-scan
+      /// flushing is handled deterministically by HDF5Printer::flush()
+      /// and HDF5Printer::finalise() instead, which iterate over the
+      /// surviving buffers in the printer's all_buffers map.
       template<class T, std::size_t L>
-      VertexBufferNumeric1D_HDF5<T,L>::~VertexBufferNumeric1D_HDF5() 
+      VertexBufferNumeric1D_HDF5<T,L>::~VertexBufferNumeric1D_HDF5()
       {
-         //TODO: Do this in some more controlled way
-         //if(this->is_synchronised()) { write_to_disk(); }
-         //else 
-         //{ 
-         //   RA_write_to_disk(); 
-         //}
       }
 
       // Print out report on buffer sync status       
diff --git a/Printers/include/gambit/Printers/printers/hdf5printer_v2.hpp b/Printers/include/gambit/Printers/printers/hdf5printer_v2.hpp
index 33a177b931..14d2be3d61 100644
--- a/Printers/include/gambit/Printers/printers/hdf5printer_v2.hpp
+++ b/Printers/include/gambit/Printers/printers/hdf5printer_v2.hpp
@@ -68,10 +68,6 @@ namespace Gambit
     typedef long long longlong;
     typedef unsigned long long ulonglong;
 
-    // DEBUG h5v2_BLOCK message counters
-    //static int recv_counter;
-    //static int send_counter;
-
     /// Length of chunks in chunked HDF5 dataset. Affects write/retrieval performance for blocks of data of various sizes.
     /// It is set to an "intermediate" sort of size since that seems to work well enough.
     static const std::size_t HDF5_CHUNKLENGTH = 100;
@@ -82,25 +78,9 @@ namespace Gambit
     /// Largest allowed size of buffers. Size can be dynamically set from 1 to this number.
     static const std::size_t MAX_BUFFER_SIZE = 100000;
 
-    /// MPI tags for HDF5 printer v2
-    const int h5v2_bufname(10);
-    const int h5v2_bufdata_points(11);
-    const int h5v2_bufdata_ranks(12);
-    const int h5v2_bufdata_valid(13);
-    const int h5v2_bufdata_type(14);
-    const int h5v2_bufdata_values(15);
-    // Message block end tag:
-    // 1 means "there is another block of messages to receive"
-    // 0 means "there are no more blocks of messages to receive"
-    const int h5v2_BLOCK(30);
-    // "Begin sending data" tag
-    const int h5v2_BEGIN(31);
-
-    // The 'h5v2_bufdata_type' messages send an integer encoding
-    // the datatype for the h5v2_bufdata_values messages
+    // The integer-encoded type ID for buffer-data messages.
     // Need a unique integer for each type. We can encode these
     // with a template function:
-
     template<class T>
     std::set<T> set_diff(const std::set<T>& set1, const std::set<T>& set2)
     {
@@ -308,6 +288,9 @@ namespace Gambit
                  errmsg << "Error! Tried to write to dataset (name="<<myname()<<") with type id "<<dtype<<" but expected it to have type id "<<expected_dtype<<". This is a bug, please report it.";
                  printer_error().raise(LOCAL_INFO, errmsg.str());
              }
+             // dtype is no longer needed, close it here to avoid leaking one 
+             // HDF5 type handle per flush per dataset.
+             H5Tclose(dtype);
 
              std::size_t required_size = target_pos+length;
              // Check that target position is allowed
@@ -638,12 +621,6 @@ namespace Gambit
         // int version
         virtual std::pair<std::vector<long>,std::vector<int>> flush_to_vector_int(const std::vector<PPIDpair>& order) = 0;
 
-#ifdef WITH_MPI
-        /// Send buffer contents to another process
-        virtual void MPI_flush_to_rank(const unsigned int r) = 0;
-
-#endif
-
         /// Make sure datasets exist on disk with the correct name and size
         virtual void ensure_dataset_exists(const hid_t loc_id, const std::size_t length) = 0;
 
@@ -905,102 +882,6 @@ namespace Gambit
             return buffer.size();
         }
 
-#ifdef WITH_MPI
-        // Send buffer contents to a different process
-        void MPI_flush_to_rank(const unsigned int r)
-        {
-            if(buffer.size()>0)
-            {
-                // Get name of the dataset this buffer is associated with
-                std::string namebuf = dset_name();
-                // Copy point data and values into MPI send buffer
-                std::vector<unsigned long> pointIDs;
-                std::vector<unsigned int> ranks; // Will assume all PPIDpairs are valid. I think this is fine to do...
-                std::vector<int> valid; // We have to send the invalid points too, to maintain buffer synchronicity
-                std::vector<T> values;
-                int type(h5v2_type<T>()); // Get integer identifying the type of the data values
-                int more_buffers = 1; // Flag indicating that there is a block of data to receive
-                for(auto it=buffer.begin(); it!=buffer.end(); ++it)
-                {
-                    pointIDs.push_back(it->first.pointID);
-                    ranks   .push_back(it->first.rank);
-                    valid   .push_back(buffer_valid.at(it->first));
-                    values  .push_back(it->second);
-                }
-
-                // Debug info
-        #ifdef HDF5PRINTER2_DEBUG
-                logger()<<LogTags::printers<<LogTags::debug<<"Sending points for buffer "<<dset_name()<<std::endl
-                                                           <<" (more_buffers: "<<more_buffers<<")"<<std::endl;
-                for(std::size_t i=0; i<buffer.size(); ++i)
-                {
-                    logger()<<"   Sending point ("<<ranks.at(i)<<", "<<pointIDs.at(i)<<")="<<values.at(i)<<" (valid="<<valid.at(i)<<")"<<std::endl;
-                }
-                logger()<<EOM;
-                #endif
-
-                // Send the buffers
-                std::size_t Npoints = values.size();
-                myComm.Send(&more_buffers, 1, r, h5v2_BLOCK);
-                //std::cerr<<myComm.Get_rank()<<": sent "<<more_buffers<<std::endl;
-                //send_counter+=1;
-                myComm.Send(&namebuf[0] , namebuf.size(), MPI_CHAR, r, h5v2_bufname);
-                myComm.Send(&type       , 1      , r, h5v2_bufdata_type);
-                myComm.Send(&values[0]  , Npoints, r, h5v2_bufdata_values);
-                myComm.Send(&pointIDs[0], Npoints, r, h5v2_bufdata_points);
-                myComm.Send(&ranks[0]   , Npoints, r, h5v2_bufdata_ranks);
-                myComm.Send(&valid[0]   , Npoints, r, h5v2_bufdata_valid);
-
-                // Clear buffer variables
-                buffer      .clear();
-                buffer_valid.clear();
-                buffer_set  .clear();
-            }
-        }
-
-        // Receive buffer contents from a different process
-        // (MasterBuffer should have received the name, type, and size of the
-        // buffer data, and used this to construct/retrieve this buffer.
-        // We then collect the buffer data messages)
-        void MPI_recv_from_rank(unsigned int r, std::size_t Npoints)
-        {
-            /// MPI buffers
-            std::vector<unsigned long> pointIDs(Npoints);
-            std::vector<unsigned int> ranks(Npoints);
-            std::vector<int> valid(Npoints);
-            std::vector<T> values(Npoints);
-
-            // Receive buffer data
-            myComm.Recv(&values[0]  , Npoints, r, h5v2_bufdata_values);
-            myComm.Recv(&pointIDs[0], Npoints, r, h5v2_bufdata_points);
-            myComm.Recv(&ranks[0]   , Npoints, r, h5v2_bufdata_ranks);
-            myComm.Recv(&valid[0]   , Npoints, r, h5v2_bufdata_valid);
-
-            // Pack it into this buffer
-        #ifdef HDF5PRINTER2_DEBUG
-            logger()<<LogTags::printers<<LogTags::debug<<"Adding points to buffer "<<dset_name()<<std::endl;
-            for(std::size_t i=0; i<Npoints; ++i)
-            {
-                // Extra Debug
-                logger()<<"   Adding received point ("<<ranks.at(i)<<", "<<pointIDs.at(i)<<")="<<values.at(i)<<" (valid="<<valid.at(i)<<")"<<std::endl;
-                PPIDpair ppid(pointIDs.at(i), ranks.at(i));
-                if(valid.at(i))
-                {
-                    append(values.at(i), ppid);
-                }
-                else
-                {
-                    update(ppid);
-                }
-            }
-            logger()<<EOM;
-            #endif
-
-            // Debug info:
-            //std::cout<<"(rank "<<myComm.Get_rank()<<") Final buffer size: "<<N_items_in_buffer()<<" (Npoints was: "<<Npoints<<"), dset="<<dset_name()<<std::endl;
-        }
-#endif
-
         void add_float_block(const HDF5bufferchunk& chunk, const std::size_t buf)
         {
             // Pack it into this buffer
@@ -1274,40 +1155,6 @@ namespace Gambit
         void print_metadata(std::map<std::string,std::string>, bool);
 
         #ifdef WITH_MPI
-        /// Gather all buffer data on a certain rank process
-        /// (only gathers data from buffers known to that process)
-        void MPI_flush_to_rank(const unsigned int rank);
-
-        /// Give process 'rank' permission to begin sending its buffer data
-        void MPI_request_buffer_data(const unsigned int rank);
-
-        /// Receive buffer data from a specified process until a STOP message is received
-        void MPI_recv_all_buffers(const unsigned int rank);
-
-        /// Receive buffer data of a known type for a known dataset
-        /// Requires status message resulting from a probe for the message to be received
-        template<class T>
-        int MPI_recv_buffer(const unsigned int r, const std::string& dset_name)
-        {
-            // Get number of points to be received
-            MPI_Status status;
-            myComm.Probe(r, h5v2_bufdata_values, &status);
-            int Npoints;
-            int err = MPI_Get_count(&status, GMPI::get_mpi_data_type<T>::type(), &Npoints);
-            if(err<0)
-            {
-                std::stringstream msg;
-                msg<<"Error from MPI_Get_count while attempting to receive buffer data from rank "<<r<<" for dataset "<<dset_name<<"!";
-                printer_error().raise(LOCAL_INFO,msg.str());
-            }
-            HDF5Buffer<T>& buffer = get_buffer<T>(dset_name, buffered_points);
-            //std::cout<<"(rank "<<myComm.Get_rank()<<") Npoints: "<<Npoints<<std::endl;
-            buffer.MPI_recv_from_rank(r, Npoints);
-            logger()<< LogTags::printers << LogTags::debug << "Received "<<Npoints<<" points from rank "<<r<<"'s buffers (for dataset: "<<dset_name<<")"<<EOM;
-            //std::cout<<"(rank "<<myComm.Get_rank()<<") Received "<<Npoints<<" from rank "<<r<<". New buffer size is "<<buffer.N_items_in_buffer()<<" (name="<<buffer.dset_name()<<")"<<std::endl;
-            return Npoints;
-        }
-
         /// Copy an MPI-transmitted block of buffer data into our buffer
         template<class T>
         void MPI_add_int_block_to_buffer(const HDF5bufferchunk& chunk, const std::string& dset_name, const std::size_t dset_index)
diff --git a/Printers/src/printers/hdf5printer/hdf5_combine_tools.cpp b/Printers/src/printers/hdf5printer/hdf5_combine_tools.cpp
index daa3fa7122..50a9f572ff 100644
--- a/Printers/src/printers/hdf5printer/hdf5_combine_tools.cpp
+++ b/Printers/src/printers/hdf5printer/hdf5_combine_tools.cpp
@@ -536,13 +536,9 @@ namespace Gambit
                                size_tot_l = size_tot + size; // Last?
                            //}
 
-                           for (auto it = valids.end()-1; size > 0; --it)
-                           {
-                               if (*it)
-                                   break;
-                               else
-                                   --size;
-                           }
+                           // Trim any trailing invalid points (size <= valids.size() ensured above)
+                           while (size > 0 && !valids[size-1])
+                               --size;
 
                            HDF5::closeSpace(dataspace);
                            HDF5::closeSpace(dataspace2);
@@ -804,13 +800,9 @@ namespace Gambit
                        ranks.push_back(valid_rank);
                        ptids.push_back(valid_ptid);
 
-                       for (auto it = valids.end()-1; size > 0; --it)
-                       {
-                           if (*it)
-                               break;
-                           else
-                               --size;
-                       }
+                       // Trim any trailing invalid points (size <= valids.size() ensured above)
+                       while (size > 0 && !valids[size-1])
+                           --size;
                        aux_sizes.push_back(size);
 
                        HDF5::closeSpace(dataspace);
@@ -992,6 +984,8 @@ namespace Gambit
                             // Close resources
                             HDF5::closeDataset(dataset_out);
                             HDF5::closeDataset(dataset2_out);
+                            H5Tclose(type);
+                            H5Tclose(type2);
 
                             // Move offset so that next batch is written to correct place in output file
                             offset += batch_size_tot + pc_offset;
@@ -1152,6 +1146,8 @@ namespace Gambit
                              }
                              // Create new dataset
                              setup_hdf5_points(new_group, type, type2, size_tot, *it);
+                             if(type>=0)  H5Tclose(type);
+                             if(type2>=0) H5Tclose(type2);
                           }
                           // Reopen output datasets for copying
                           hid_t dataset_out  = HDF5::openDataset(new_group, *it);
@@ -1307,6 +1303,7 @@ namespace Gambit
 
                             // Close resources
                             HDF5::closeDataset(dataset_out);
+                            H5Tclose(type);
 
                             // Move offset so that next batch is written to correct place in output file
                             offset += batch_size_tot + pc_offset;
diff --git a/Printers/src/printers/hdf5printer/hdf5printer.cpp b/Printers/src/printers/hdf5printer/hdf5printer.cpp
index 0f861b3f7c..32f9a3e9ef 100644
--- a/Printers/src/printers/hdf5printer/hdf5printer.cpp
+++ b/Printers/src/printers/hdf5printer/hdf5printer.cpp
@@ -465,7 +465,16 @@ namespace Gambit
                   printer_error().raise(LOCAL_INFO, errmsg.str());
                 }
                 HDF5::closeFile(file_id);
-                exit(1);
+                // Group does not exist in the pre-existing file. Refuse to
+                // proceed: we are not in resume mode and 'delete_file_on_restart'
+                // is not set, so adding a new group to a file from an unrelated
+                // previous run risks silently mixing unrelated data.
+                std::ostringstream errmsg2;
+                errmsg2 << "Error preparing pre-existing output file '"<<finalfile<<"' for writing via hdf5printer! The file exists, but does not contain the requested output group '"<<group<<"', and the run is not in resume mode (so we will not append to it) and 'delete_file_on_restart' is not set (so we will not overwrite it). Refusing to proceed to avoid silently mixing unrelated data. Please take one of the following actions:"<<std::endl;
+                errmsg2 << "  1. Re-run with the -r flag (restart) and set 'delete_file_on_restart: true' to overwrite the existing file;"<<std::endl;
+                errmsg2 << "  2. Choose a different output filename via the 'output_file' printer option;"<<std::endl;
+                errmsg2 << "  3. Manually move or delete the existing file '"<<finalfile<<"'."<<std::endl;
+                printer_error().raise(LOCAL_INFO, errmsg2.str());
               }
 
             }
@@ -1303,6 +1312,12 @@ namespace Gambit
         printer_error().raise(LOCAL_INFO, errmsg.str());
       }
 
+      // If sync_pos is still 0 then no point has yet been registered as the
+      // current sync position, so there is no "previous slot" for buffers to
+      // catch up to. Return early. (The get_sync_pos()-1 below would be an 
+      // unsigned underflow when get_sync_pos() = 0.)
+      if(get_sync_pos()==0) return;
+
       // Determine the desired sync position
       const unsigned long sync_pos = get_sync_pos()-1;
 
@@ -1378,9 +1393,8 @@ namespace Gambit
       }
 
       // Tell the HDF5 library to flush everything to disk.
-      // Auxiliary printers don't own a file handle (only the primary opens
-      // the HDF5 file in its constructor), so always flush via the primary's
-      // file_id. For the primary itself, primary_printer == this.
+      // Auxiliary printers don't own a file handle, so always 
+      // flush via the primary's file_id.
       herr_t err = H5Fflush(primary_printer->file_id, H5F_SCOPE_GLOBAL);
       if(err<0)
       {
diff --git a/Printers/src/printers/hdf5printer/hdf5tools.cpp b/Printers/src/printers/hdf5printer/hdf5tools.cpp
index 720f25d1eb..df8606caa6 100644
--- a/Printers/src/printers/hdf5printer/hdf5tools.cpp
+++ b/Printers/src/printers/hdf5printer/hdf5tools.cpp
@@ -667,9 +667,15 @@ namespace Gambit {
       /// Close hdf5 group
       SIMPLE_CALL(hid_t, closeGroup,  hid_t, H5Gclose, "close", "group", "group")
 
-      /// global error variables (handler)
-      H5E_auto2_t old_func;
-      void *old_client_data;
+      /// State for errorsOff() / errorsOn(). The bool guard errors_are_off 
+      /// ensures that a redundant errorsOff() called while errors are already 
+      /// off does NOT overwrite the saved handler with the NULL handler.
+      namespace
+      {
+         bool errors_are_off = false;
+         H5E_auto2_t saved_func = nullptr;
+         void *saved_client_data = nullptr;
+      }
 
       // FIXME: This caused compile problems on LISA cluster (CW)
       /// Silence error report (e.g. while probing for file existence)
@@ -683,18 +689,21 @@ namespace Gambit {
       /// and let me know if it works :)
       void errorsOff()
       {
+         if (errors_are_off) return; // already off; don't clobber saved state
          /* Save old error handler */
-         H5Eget_auto2(H5E_DEFAULT, &old_func, &old_client_data);
-
+         H5Eget_auto2(H5E_DEFAULT, &saved_func, &saved_client_data);
          /* Turn off error handling */
          H5Eset_auto2(H5E_DEFAULT, NULL, NULL);
+         errors_are_off = true;
       }
 
       /// Restore error report
       void errorsOn()
       {
+         if (!errors_are_off) return; // unbalanced / already on; no-op
          /* Restore previous error handler */
-         H5Eset_auto2(H5E_DEFAULT, old_func, old_client_data);
+         H5Eset_auto2(H5E_DEFAULT, saved_func, saved_client_data);
+         errors_are_off = false;
       }
 
       /// @{ Dataset manipulations
diff --git a/Printers/src/printers/hdf5printer_v2/hdf5printer_v2.cpp b/Printers/src/printers/hdf5printer_v2/hdf5printer_v2.cpp
index 410b27abe3..b6cbf39f50 100644
--- a/Printers/src/printers/hdf5printer_v2/hdf5printer_v2.cpp
+++ b/Printers/src/printers/hdf5printer_v2/hdf5printer_v2.cpp
@@ -660,108 +660,6 @@ namespace Gambit
     }
 
     #ifdef WITH_MPI
-    /// Send buffer data to a specified process
-    void HDF5MasterBuffer::MPI_flush_to_rank(const unsigned int r)
-    {
-        for(auto it=all_buffers.begin(); it!=all_buffers.end(); ++it)
-        {
-            it->second->MPI_flush_to_rank(r);
-        }
-        buffered_points.clear();
-        buffered_points_set.clear();
-    }
-
-    /// Give process r permission to begin sending its buffer data
-    // Don't do this for all processes at once, as MPI can run out of
-    // Recv request IDs behind the scenes if thousands of processes are
-    // trying to send it lots of stuff at once. But it is good to let
-    // many processes start sending data before we need it, so that the
-    // Recv goes quickly (and is effectively already done in the background)
-    // when we get to it.
-    void HDF5MasterBuffer::MPI_request_buffer_data(const unsigned int r)
-    {
-        logger()<< LogTags::printers << LogTags::info << "Asking process "<<r<<" to begin sending buffer data"<<EOM;
-        // Send a message to the process to trigger it to begin sending buffer data (if any exists)
-        int begin_sending = 1;
-        myComm.Send(&begin_sending, 1, r, h5v2_BEGIN);
-    }
-
-    /// Receive buffer data from a specified process until a STOP message is received
-    void HDF5MasterBuffer::MPI_recv_all_buffers(const unsigned int r)
-    {
-        // MAKE SURE MPI_request_buffer_data(r) HAS BEEN CALLED BEFORE THIS FUNCTION!
-        // Otherwise a deadlock will occur because we will wait forever for buffer data
-        // that will never be sent.
-
-        int more_buffers = 1;
-        int max_Npoints = 0; // Track largest buffer sent, for reporting general number of points recv'd
-        int Nbuffers = 0; // Number of buffers recv'd
-        while(more_buffers)
-        {
-            // Check "more buffers" message
-            myComm.Recv(&more_buffers, 1, r, h5v2_BLOCK);
-            //recv_counter+=1;
-            logger()<<LogTags::printers<<LogTags::debug<<"More buffers to receive from process "<<r<<"? "<<more_buffers<<EOM;
-            if(more_buffers)
-            {
-                Nbuffers+=1;
-                // Retrieve the name of the dataset for the buffer data
-                MPI_Status status;
-                myComm.Probe(r, h5v2_bufname, &status);
-                int name_size;
-                int err = MPI_Get_count(&status, MPI_CHAR, &name_size);
-                if(err<0)
-                {
-                    std::ostringstream errmsg;
-                    errmsg<<"MPI_Get_count failed while trying to get name of dataset to receive!";
-                    printer_error().raise(LOCAL_INFO, errmsg.str());
-                }
-                std::string dset_name(name_size, 'x'); // Initialise string to correct size, but filled with x's
-                myComm.Recv(&dset_name[0], name_size, MPI_CHAR, r, h5v2_bufname);
-
-                logger()<<LogTags::printers<<LogTags::debug<<"Preparing to receive buffer data from process "<<r<<" for buffer "<<dset_name<<EOM;
-
-                // Get datatype of buffer data, and call matching receive function for that type
-                int buftype;
-                myComm.Recv(&buftype, 1, r, h5v2_bufdata_type);
-                int Npoints = 0;
-                switch(buftype)
-                {
-                    case h5v2_type<int      >(): Npoints = MPI_recv_buffer<int      >(r, dset_name); break;
-                    case h5v2_type<uint     >(): Npoints = MPI_recv_buffer<uint     >(r, dset_name); break;
-                    case h5v2_type<long     >(): Npoints = MPI_recv_buffer<long     >(r, dset_name); break;
-                    case h5v2_type<ulong    >(): Npoints = MPI_recv_buffer<ulong    >(r, dset_name); break;
-                    //case h5v2_type<longlong >(): Npoints = MPI_recv_buffer<longlong >(r, dset_name); break;
-                    //case h5v2_type<ulonglong>(): Npoints = MPI_recv_buffer<ulonglong>(r, dset_name); break;
-                    case h5v2_type<float    >(): Npoints = MPI_recv_buffer<float    >(r, dset_name); break;
-                    case h5v2_type<double   >(): Npoints = MPI_recv_buffer<double   >(r, dset_name); break;
-                    default:
-                       std::ostringstream errmsg;
-                       errmsg<<"Unrecognised datatype integer (value = "<<buftype<<") received in buffer type message from rank "<<r<<" for dataset "<<dset_name<<"!";
-                       printer_error().raise(LOCAL_INFO, errmsg.str());
-                }
-                if(Npoints>max_Npoints) max_Npoints = Npoints;
-            }
-        }
-
-        logger()<<LogTags::printers<<LogTags::info;
-        if(max_Npoints==0)
-        {
-           logger()<<"No print buffer data recv'd from rank "<<r<<" process"<<std::endl;
-        }
-        else
-        {
-           logger()<<"Recv'd "<<Nbuffers<<" dataset buffers from rank "<<r<<"; the largest one contained "<<max_Npoints<<" points"<<std::endl;
-        }
-        // Debug
-        //for(auto it=all_buffers.begin(); it!=all_buffers.end(); ++it)
-        //{
-        //    std::cout<<"New buffer length is "<<it->second->N_items_in_buffer()<<" (name="<<it->second->dset_name()<<")"<<std::endl;
-        //}
-
-        logger()<<"Finished checking for buffer data messages from process "<<r<<EOM;
-    }
-
     // Add a vector of buffer chunk data to the buffers managed by this object
     void HDF5MasterBuffer::add_to_buffers(const std::vector<HDF5bufferchunk>& blocks, const std::vector<std::pair<std::string,int>>& buf_types)
     {
@@ -1875,17 +1773,32 @@ namespace Gambit
     // Flush data in buffers to disk
     void HDF5Printer2::flush()
     {
+        // Each rank writes its own buffered points under the cross-rank
+        // Utils::FileLock taken inside HDF5MasterBuffer::flush(); no MPI
+        // gather here. The collective gather happens only in finalise().
+        // Auxilliary printers register their buffermaster into the primary's
+        // aux_buffers (see constructor) and have an empty aux_buffers
+        // themselves, so only the primary needs to iterate.
+        // Sync streams before RA streams: matches finalise()'s ordering,
+        // since RA writes target positions established by sync writes.
         buffermaster.flush();
+        if(not is_auxilliary_printer())
+        {
+            for(auto it=aux_buffers.begin(); it!=aux_buffers.end(); ++it)
+            {
+                if((*it)->is_synchronised()) (*it)->flush();
+            }
+            for(auto it=aux_buffers.begin(); it!=aux_buffers.end(); ++it)
+            {
+                if(not (*it)->is_synchronised()) (*it)->flush();
+            }
+        }
     }
 
     // Make sure printer output is fully on disk and safe
     // No distinction between final and early termination procedure for this printer.
     void HDF5Printer2::finalise(bool /*abnormal*/)
     {
-        // DEBUG h5v2_BLOCK message counter
-        //recv_counter = 0;
-        //send_counter = 0;
-
         // The primary printer will take care of finalising all output.
         if(not is_auxilliary_printer())
         {
@@ -1955,16 +1868,6 @@ namespace Gambit
 
             std::ostringstream buffer_nonempty_report;
             bool buffer_nonempty_warn(false);
-            std::size_t final_size;
-            if(myRank==0)
-            {
-                /// Need to know final nominal dataset size to ensure unsynchronised datasets match synchronised ones.
-                buffermaster.lock_and_open_file();
-                final_size = buffermaster.get_next_free_position();
-                buffermaster.close_and_unlock_file();
-                std::cout<<"Final dataset size is "<<final_size<<std::endl;
-                logger()<< LogTags::printers << LogTags::info << "Final dataset size is "<<final_size<<EOM;
-            }
 
             #ifdef WITH_MPI
             // Gather RA print buffer data from all other processes
@@ -1989,23 +1892,39 @@ namespace Gambit
                 // So just stick any buffermanager object as the argument to satisfy the function signature requirements.
                 gather_and_print(buffermaster,RA_buffers,false);
             }
-
-            // Try to flush everything left to disk
-            add_aux_buffer(RAbuffer); // Make sure to include 'gathered' RA data, if there is any.
             #endif
-            for(auto it=aux_buffers.begin(); it!=aux_buffers.end(); ++it)
+
+            // Only rank 0 owns the output file, so only rank 0 should flush
+            // RA buffers to disk and extend the unsynchronised datasets to the
+            // final nominal size. Worker ranks have already shipped their RA
+            // data to rank 0 via gather_and_print above.
+            if(myRank==0)
             {
-                if(not (*it)->is_synchronised())
+                /// Need to know final nominal dataset size to ensure unsynchronised datasets match synchronised ones.
+                buffermaster.lock_and_open_file();
+                std::size_t final_size = buffermaster.get_next_free_position();
+                buffermaster.close_and_unlock_file();
+                std::cout<<"Final dataset size is "<<final_size<<std::endl;
+                logger()<< LogTags::printers << LogTags::info << "Final dataset size is "<<final_size<<EOM;
+
+                #ifdef WITH_MPI
+                // Try to flush everything left to disk
+                add_aux_buffer(RAbuffer); // Make sure to include 'gathered' RA data, if there is any.
+                #endif
+                for(auto it=aux_buffers.begin(); it!=aux_buffers.end(); ++it)
                 {
-                    (*it)->flush();
-                    // Check if everything managed to flush!
-                    if(not (*it)->all_buffers_empty())
+                    if(not (*it)->is_synchronised())
                     {
-                        buffer_nonempty_report<<(*it)->buffer_status();
-                        buffer_nonempty_warn = true;
+                        (*it)->flush();
+                        // Check if everything managed to flush!
+                        if(not (*it)->all_buffers_empty())
+                        {
+                            buffer_nonempty_report<<(*it)->buffer_status();
+                            buffer_nonempty_warn = true;
+                        }
+                        // Make sure final dataset size is correct for the unsynchronised buffers
+                        (*it)->extend_all_datasets_to(final_size);
                     }
-                    // Make sure final dataset size is correct for the unsynchronised buffers
-                    (*it)->extend_all_datasets_to(final_size);
                 }
             }
 
@@ -2020,10 +1939,6 @@ namespace Gambit
             }
 
             logger()<< LogTags::printers << LogTags::info << "HDF5Printer2 output finalisation complete."<<EOM;
-
-            // DEBUG
-            //logger()<<LogTags::printers<<LogTags::debug<<"h5v2_BLOCK send count: "<<send_counter<<std::endl
-            //                                           <<"h5v2_BLOCK recv count: "<<recv_counter<<EOM;
         }
     }