fixup! Fix load explosion: use subprocess for binary data plots to avoid thread conflict

* Seems we don't have to set so many variables, `OMP_NUM_THREADS` is enough. Test: Annotate the code for setting other environment variables. It runs normally.
Fix load explosion: use subprocess for binary data plots to avoid thread conflict
2026-02-09 23:00:17 +08:00 · 2026-02-09 21:40:27 +08:00 · 2026-02-09 21:36:45 +08:00 · 2026-02-09 15:13:18 +08:00 · 2026-02-08 16:46:44 +08:00 · 2026-02-08 16:19:13 +08:00
11 changed files with 836 additions and 108 deletions
--- a/AMSS_NCKU_Program.py
+++ b/AMSS_NCKU_Program.py
@@ -8,6 +8,14 @@
 ##
 ##################################################################

+## Guard against re-execution by multiprocessing child processes.
+## Without this, using 'spawn' or 'forkserver' context would cause every
+## worker to re-run the entire script, spawning exponentially more
+## workers (fork bomb).
+if __name__ != '__main__':
+    import sys as _sys
+    _sys.exit(0)
+

 ##################################################################

@@ -424,26 +432,31 @@ print(

 import plot_xiaoqu
 import plot_GW_strain_amplitude_xiaoqu
+from parallel_plot_helper import run_plot_tasks_parallel
+
+plot_tasks = []

 ## Plot black hole trajectory
-plot_xiaoqu.generate_puncture_orbit_plot(   binary_results_directory, figure_directory )
-plot_xiaoqu.generate_puncture_orbit_plot3D( binary_results_directory, figure_directory )
+plot_tasks.append( ( plot_xiaoqu.generate_puncture_orbit_plot,   (binary_results_directory, figure_directory) ) )
+plot_tasks.append( ( plot_xiaoqu.generate_puncture_orbit_plot3D, (binary_results_directory, figure_directory) ) )

 ## Plot black hole separation vs. time
-plot_xiaoqu.generate_puncture_distence_plot( binary_results_directory, figure_directory )
+plot_tasks.append( ( plot_xiaoqu.generate_puncture_distence_plot, (binary_results_directory, figure_directory) ) )

 ## Plot gravitational waveforms (psi4 and strain amplitude)
 for i in range(input_data.Detector_Number):
-    plot_xiaoqu.generate_gravitational_wave_psi4_plot( binary_results_directory, figure_directory, i )
-    plot_GW_strain_amplitude_xiaoqu.generate_gravitational_wave_amplitude_plot( binary_results_directory, figure_directory, i )
+    plot_tasks.append( ( plot_xiaoqu.generate_gravitational_wave_psi4_plot, (binary_results_directory, figure_directory, i) ) )
+    plot_tasks.append( ( plot_GW_strain_amplitude_xiaoqu.generate_gravitational_wave_amplitude_plot, (binary_results_directory, figure_directory, i) ) )

 ## Plot ADM mass evolution
 for i in range(input_data.Detector_Number):
-    plot_xiaoqu.generate_ADMmass_plot( binary_results_directory, figure_directory, i )
+    plot_tasks.append( ( plot_xiaoqu.generate_ADMmass_plot, (binary_results_directory, figure_directory, i) ) )

 ## Plot Hamiltonian constraint violation over time
 for i in range(input_data.grid_level):
-    plot_xiaoqu.generate_constraint_check_plot( binary_results_directory, figure_directory, i )
+    plot_tasks.append( ( plot_xiaoqu.generate_constraint_check_plot, (binary_results_directory, figure_directory, i) ) )
+
+run_plot_tasks_parallel(plot_tasks)

 ## Plot stored binary data
 plot_xiaoqu.generate_binary_data_plot( binary_results_directory, figure_directory )
--- a/AMSS_NCKU_source/Parallel.C
+++ b/AMSS_NCKU_source/Parallel.C
@@ -3756,6 +3756,358 @@ void Parallel::Sync(MyList<Patch> *PatL, MyList<var> *VarList, int Symmetry)
  delete[] transfer_src;
  delete[] transfer_dst;
 }
+//
+// Async Sync: split into SyncBegin (initiate MPI) and SyncEnd (wait + unpack)
+// This allows overlapping MPI communication with computation.
+//
+static void transfer_begin(Parallel::TransferState *ts)
+{
+  int myrank;
+  MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
+  int cpusize = ts->cpusize;
+
+  ts->reqs = new MPI_Request[2 * cpusize];
+  ts->stats = new MPI_Status[2 * cpusize];
+  ts->req_no = 0;
+  ts->send_data = new double *[cpusize];
+  ts->rec_data = new double *[cpusize];
+  int length;
+
+  for (int node = 0; node < cpusize; node++)
+  {
+    ts->send_data[node] = ts->rec_data[node] = 0;
+    if (node == myrank)
+    {
+      // Local copy: pack then immediately unpack (no MPI needed)
+      if ((length = Parallel::data_packer(0, ts->transfer_src[myrank], ts->transfer_dst[myrank],
+                                          node, PACK, ts->VarList1, ts->VarList2, ts->Symmetry)))
+      {
+        double *local_data = new double[length];
+        if (!local_data)
+        {
+          cout << "out of memory in transfer_begin, local copy" << endl;
+          MPI_Abort(MPI_COMM_WORLD, 1);
+        }
+        Parallel::data_packer(local_data, ts->transfer_src[myrank], ts->transfer_dst[myrank],
+                              node, PACK, ts->VarList1, ts->VarList2, ts->Symmetry);
+        Parallel::data_packer(local_data, ts->transfer_src[node], ts->transfer_dst[node],
+                              node, UNPACK, ts->VarList1, ts->VarList2, ts->Symmetry);
+        delete[] local_data;
+      }
+    }
+    else
+    {
+      // send from this cpu to cpu#node
+      if ((length = Parallel::data_packer(0, ts->transfer_src[myrank], ts->transfer_dst[myrank],
+                                          node, PACK, ts->VarList1, ts->VarList2, ts->Symmetry)))
+      {
+        ts->send_data[node] = new double[length];
+        if (!ts->send_data[node])
+        {
+          cout << "out of memory in transfer_begin, send" << endl;
+          MPI_Abort(MPI_COMM_WORLD, 1);
+        }
+        Parallel::data_packer(ts->send_data[node], ts->transfer_src[myrank], ts->transfer_dst[myrank],
+                              node, PACK, ts->VarList1, ts->VarList2, ts->Symmetry);
+        MPI_Isend((void *)ts->send_data[node], length, MPI_DOUBLE, node, 1, MPI_COMM_WORLD,
+                  ts->reqs + ts->req_no++);
+      }
+      // receive from cpu#node to this cpu
+      if ((length = Parallel::data_packer(0, ts->transfer_src[node], ts->transfer_dst[node],
+                                          node, UNPACK, ts->VarList1, ts->VarList2, ts->Symmetry)))
+      {
+        ts->rec_data[node] = new double[length];
+        if (!ts->rec_data[node])
+        {
+          cout << "out of memory in transfer_begin, recv" << endl;
+          MPI_Abort(MPI_COMM_WORLD, 1);
+        }
+        MPI_Irecv((void *)ts->rec_data[node], length, MPI_DOUBLE, node, 1, MPI_COMM_WORLD,
+                  ts->reqs + ts->req_no++);
+      }
+    }
+  }
+  // NOTE: MPI_Waitall is NOT called here - that happens in transfer_end
+}
+//
+static void transfer_end(Parallel::TransferState *ts)
+{
+  // Wait for all pending MPI operations
+  MPI_Waitall(ts->req_no, ts->reqs, ts->stats);
+
+  // Unpack received data from remote ranks
+  for (int node = 0; node < ts->cpusize; node++)
+    if (ts->rec_data[node])
+      Parallel::data_packer(ts->rec_data[node], ts->transfer_src[node], ts->transfer_dst[node],
+                            node, UNPACK, ts->VarList1, ts->VarList2, ts->Symmetry);
+
+  // Cleanup MPI buffers
+  for (int node = 0; node < ts->cpusize; node++)
+  {
+    if (ts->send_data[node])
+      delete[] ts->send_data[node];
+    if (ts->rec_data[node])
+      delete[] ts->rec_data[node];
+  }
+  delete[] ts->reqs;
+  delete[] ts->stats;
+  delete[] ts->send_data;
+  delete[] ts->rec_data;
+}
+//
+Parallel::SyncHandle *Parallel::SyncBegin(Patch *Pat, MyList<var> *VarList, int Symmetry)
+{
+  int cpusize;
+  MPI_Comm_size(MPI_COMM_WORLD, &cpusize);
+
+  SyncHandle *handle = new SyncHandle;
+  handle->num_states = 1;
+  handle->states = new TransferState[1];
+
+  TransferState *ts = &handle->states[0];
+  ts->cpusize = cpusize;
+  ts->VarList1 = VarList;
+  ts->VarList2 = VarList;
+  ts->Symmetry = Symmetry;
+  ts->owns_gsl = true;
+
+  ts->dst = build_ghost_gsl(Pat);
+  ts->src = new MyList<Parallel::gridseg> *[cpusize];
+  ts->transfer_src = new MyList<Parallel::gridseg> *[cpusize];
+  ts->transfer_dst = new MyList<Parallel::gridseg> *[cpusize];
+  for (int node = 0; node < cpusize; node++)
+  {
+    ts->src[node] = build_owned_gsl0(Pat, node);
+    build_gstl(ts->src[node], ts->dst, &ts->transfer_src[node], &ts->transfer_dst[node]);
+  }
+
+  transfer_begin(ts);
+
+  return handle;
+}
+//
+Parallel::SyncHandle *Parallel::SyncBegin(MyList<Patch> *PatL, MyList<var> *VarList, int Symmetry)
+{
+  int cpusize;
+  MPI_Comm_size(MPI_COMM_WORLD, &cpusize);
+
+  // Count patches
+  int num_patches = 0;
+  MyList<Patch> *Pp = PatL;
+  while (Pp) { num_patches++; Pp = Pp->next; }
+
+  SyncHandle *handle = new SyncHandle;
+  handle->num_states = num_patches + 1; // intra-patch transfers + 1 inter-patch transfer
+  handle->states = new TransferState[handle->num_states];
+
+  // Intra-patch sync: for each patch, build ghost lists and initiate transfer
+  int idx = 0;
+  Pp = PatL;
+  while (Pp)
+  {
+    TransferState *ts = &handle->states[idx];
+    ts->cpusize = cpusize;
+    ts->VarList1 = VarList;
+    ts->VarList2 = VarList;
+    ts->Symmetry = Symmetry;
+    ts->owns_gsl = true;
+
+    ts->dst = build_ghost_gsl(Pp->data);
+    ts->src = new MyList<Parallel::gridseg> *[cpusize];
+    ts->transfer_src = new MyList<Parallel::gridseg> *[cpusize];
+    ts->transfer_dst = new MyList<Parallel::gridseg> *[cpusize];
+    for (int node = 0; node < cpusize; node++)
+    {
+      ts->src[node] = build_owned_gsl0(Pp->data, node);
+      build_gstl(ts->src[node], ts->dst, &ts->transfer_src[node], &ts->transfer_dst[node]);
+    }
+
+    transfer_begin(ts);
+
+    idx++;
+    Pp = Pp->next;
+  }
+
+  // Inter-patch sync: buffer zone exchange between patches
+  {
+    TransferState *ts = &handle->states[idx];
+    ts->cpusize = cpusize;
+    ts->VarList1 = VarList;
+    ts->VarList2 = VarList;
+    ts->Symmetry = Symmetry;
+    ts->owns_gsl = true;
+
+    ts->dst = build_buffer_gsl(PatL);
+    ts->src = new MyList<Parallel::gridseg> *[cpusize];
+    ts->transfer_src = new MyList<Parallel::gridseg> *[cpusize];
+    ts->transfer_dst = new MyList<Parallel::gridseg> *[cpusize];
+    for (int node = 0; node < cpusize; node++)
+    {
+      ts->src[node] = build_owned_gsl(PatL, node, 5, Symmetry);
+      build_gstl(ts->src[node], ts->dst, &ts->transfer_src[node], &ts->transfer_dst[node]);
+    }
+
+    transfer_begin(ts);
+  }
+
+  return handle;
+}
+//
+void Parallel::SyncEnd(SyncHandle *handle)
+{
+  if (!handle)
+    return;
+
+  // Wait for all pending transfers and unpack
+  for (int i = 0; i < handle->num_states; i++)
+  {
+    TransferState *ts = &handle->states[i];
+    transfer_end(ts);
+
+    // Cleanup grid segment lists only if this state owns them
+    if (ts->owns_gsl)
+    {
+      if (ts->dst)
+        ts->dst->destroyList();
+      for (int node = 0; node < ts->cpusize; node++)
+      {
+        if (ts->src[node])
+          ts->src[node]->destroyList();
+        if (ts->transfer_src[node])
+          ts->transfer_src[node]->destroyList();
+        if (ts->transfer_dst[node])
+          ts->transfer_dst[node]->destroyList();
+      }
+      delete[] ts->src;
+      delete[] ts->transfer_src;
+      delete[] ts->transfer_dst;
+    }
+  }
+
+  delete[] handle->states;
+  delete handle;
+}
+//
+// SyncPreparePlan: Pre-build grid segment lists for a patch list.
+// The plan can be reused across multiple SyncBeginWithPlan calls
+// as long as the mesh topology does not change (no regridding).
+//
+Parallel::SyncPlan *Parallel::SyncPreparePlan(MyList<Patch> *PatL, int Symmetry)
+{
+  int cpusize;
+  MPI_Comm_size(MPI_COMM_WORLD, &cpusize);
+
+  // Count patches
+  int num_patches = 0;
+  MyList<Patch> *Pp = PatL;
+  while (Pp) { num_patches++; Pp = Pp->next; }
+
+  SyncPlan *plan = new SyncPlan;
+  plan->num_entries = num_patches + 1; // intra-patch + 1 inter-patch
+  plan->Symmetry = Symmetry;
+  plan->entries = new SyncPlanEntry[plan->num_entries];
+
+  // Intra-patch entries: ghost zone exchange within each patch
+  int idx = 0;
+  Pp = PatL;
+  while (Pp)
+  {
+    SyncPlanEntry *pe = &plan->entries[idx];
+    pe->cpusize = cpusize;
+    pe->dst = build_ghost_gsl(Pp->data);
+    pe->src = new MyList<Parallel::gridseg> *[cpusize];
+    pe->transfer_src = new MyList<Parallel::gridseg> *[cpusize];
+    pe->transfer_dst = new MyList<Parallel::gridseg> *[cpusize];
+    for (int node = 0; node < cpusize; node++)
+    {
+      pe->src[node] = build_owned_gsl0(Pp->data, node);
+      build_gstl(pe->src[node], pe->dst, &pe->transfer_src[node], &pe->transfer_dst[node]);
+    }
+    idx++;
+    Pp = Pp->next;
+  }
+
+  // Inter-patch entry: buffer zone exchange between patches
+  {
+    SyncPlanEntry *pe = &plan->entries[idx];
+    pe->cpusize = cpusize;
+    pe->dst = build_buffer_gsl(PatL);
+    pe->src = new MyList<Parallel::gridseg> *[cpusize];
+    pe->transfer_src = new MyList<Parallel::gridseg> *[cpusize];
+    pe->transfer_dst = new MyList<Parallel::gridseg> *[cpusize];
+    for (int node = 0; node < cpusize; node++)
+    {
+      pe->src[node] = build_owned_gsl(PatL, node, 5, Symmetry);
+      build_gstl(pe->src[node], pe->dst, &pe->transfer_src[node], &pe->transfer_dst[node]);
+    }
+  }
+
+  return plan;
+}
+//
+void Parallel::SyncFreePlan(SyncPlan *plan)
+{
+  if (!plan)
+    return;
+
+  for (int i = 0; i < plan->num_entries; i++)
+  {
+    SyncPlanEntry *pe = &plan->entries[i];
+    if (pe->dst)
+      pe->dst->destroyList();
+    for (int node = 0; node < pe->cpusize; node++)
+    {
+      if (pe->src[node])
+        pe->src[node]->destroyList();
+      if (pe->transfer_src[node])
+        pe->transfer_src[node]->destroyList();
+      if (pe->transfer_dst[node])
+        pe->transfer_dst[node]->destroyList();
+    }
+    delete[] pe->src;
+    delete[] pe->transfer_src;
+    delete[] pe->transfer_dst;
+  }
+  delete[] plan->entries;
+  delete plan;
+}
+//
+// SyncBeginWithPlan: Use pre-built GSLs from a SyncPlan to initiate async transfer.
+// This avoids the O(cpusize * blocks^2) cost of rebuilding GSLs on every call.
+//
+Parallel::SyncHandle *Parallel::SyncBeginWithPlan(SyncPlan *plan, MyList<var> *VarList)
+{
+  return SyncBeginWithPlan(plan, VarList, VarList);
+}
+//
+Parallel::SyncHandle *Parallel::SyncBeginWithPlan(SyncPlan *plan, MyList<var> *VarList1, MyList<var> *VarList2)
+{
+  SyncHandle *handle = new SyncHandle;
+  handle->num_states = plan->num_entries;
+  handle->states = new TransferState[handle->num_states];
+
+  for (int i = 0; i < plan->num_entries; i++)
+  {
+    SyncPlanEntry *pe = &plan->entries[i];
+    TransferState *ts = &handle->states[i];
+
+    ts->cpusize = pe->cpusize;
+    ts->VarList1 = VarList1;
+    ts->VarList2 = VarList2;
+    ts->Symmetry = plan->Symmetry;
+    ts->owns_gsl = false; // GSLs are owned by the plan, not this handle
+
+    // Borrow GSL pointers from the plan (do NOT free them in SyncEnd)
+    ts->transfer_src = pe->transfer_src;
+    ts->transfer_dst = pe->transfer_dst;
+    ts->src = pe->src;
+    ts->dst = pe->dst;
+
+    transfer_begin(ts);
+  }
+
+  return handle;
+}
 // collect buffer grid segments or blocks for the periodic boundary condition of given patch
 // ---------------------------------------------------
 // |con |                                       |con |
--- a/AMSS_NCKU_source/Parallel.h
+++ b/AMSS_NCKU_source/Parallel.h
@@ -81,6 +81,53 @@ namespace Parallel
                   int Symmetry);
  void Sync(Patch *Pat, MyList<var> *VarList, int Symmetry);
  void Sync(MyList<Patch> *PatL, MyList<var> *VarList, int Symmetry);
+
+  // Async Sync: overlap MPI communication with computation
+  struct TransferState
+  {
+    MPI_Request *reqs;
+    MPI_Status *stats;
+    int req_no;
+    double **send_data;
+    double **rec_data;
+    int cpusize;
+    MyList<gridseg> **transfer_src;
+    MyList<gridseg> **transfer_dst;
+    MyList<gridseg> **src;
+    MyList<gridseg> *dst;
+    MyList<var> *VarList1;
+    MyList<var> *VarList2;
+    int Symmetry;
+    bool owns_gsl; // true if this state owns and should free the GSLs
+  };
+  struct SyncHandle
+  {
+    TransferState *states;
+    int num_states;
+  };
+  SyncHandle *SyncBegin(Patch *Pat, MyList<var> *VarList, int Symmetry);
+  SyncHandle *SyncBegin(MyList<Patch> *PatL, MyList<var> *VarList, int Symmetry);
+  void SyncEnd(SyncHandle *handle);
+
+  // Cached GSL plan: pre-build grid segment lists once, reuse across multiple Sync calls
+  struct SyncPlanEntry
+  {
+    int cpusize;
+    MyList<gridseg> **transfer_src;
+    MyList<gridseg> **transfer_dst;
+    MyList<gridseg> **src;
+    MyList<gridseg> *dst;
+  };
+  struct SyncPlan
+  {
+    SyncPlanEntry *entries;
+    int num_entries;
+    int Symmetry;
+  };
+  SyncPlan *SyncPreparePlan(MyList<Patch> *PatL, int Symmetry);
+  void SyncFreePlan(SyncPlan *plan);
+  SyncHandle *SyncBeginWithPlan(SyncPlan *plan, MyList<var> *VarList);
+  SyncHandle *SyncBeginWithPlan(SyncPlan *plan, MyList<var> *VarList1, MyList<var> *VarList2);
  void OutBdLow2Hi(Patch *Patc, Patch *Patf,
                   MyList<var> *VarList1 /* source */, MyList<var> *VarList2 /* target */,
                   int Symmetry);
--- a/AMSS_NCKU_source/Z4c_class.C
+++ b/AMSS_NCKU_source/Z4c_class.C
@@ -186,6 +186,12 @@ void Z4c_class::Step(int lev, int YN)
  int ERROR = 0;

  MyList<ss_patch> *sPp;
+
+  // Pre-build grid segment lists once for this level's patches.
+  // These are reused across predictor + 3 corrector SyncBegin calls,
+  // avoiding O(cpusize * blocks^2) rebuild each time.
+  Parallel::SyncPlan *sync_plan = Parallel::SyncPreparePlan(GH->PatL[lev], Symmetry);
+
  // Predictor
  MyList<Patch> *Pp = GH->PatL[lev];
  while (Pp)
@@ -321,13 +327,17 @@ void Z4c_class::Step(int lev, int YN)
    }
    Pp = Pp->next;
  }
-  // check error information
+  // Start async ghost zone exchange - overlaps with error check and Shell computation
+  Parallel::SyncHandle *sync_pre = Parallel::SyncBeginWithPlan(sync_plan, SynchList_pre);
+
+  // check error information (overlaps with MPI transfer)
  {
    int erh = ERROR;
    MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
  }
  if (ERROR)
  {
+    Parallel::SyncEnd(sync_pre); sync_pre = 0;
    Parallel::Dump_Data(GH->PatL[lev], StateList, 0, PhysTime, dT_lev);
    if (myrank == 0)
    {
@@ -475,6 +485,7 @@ void Z4c_class::Step(int lev, int YN)
  }
  if (ERROR)
  {
+    Parallel::SyncEnd(sync_pre); sync_pre = 0;
    SH->Dump_Data(StateList, 0, PhysTime, dT_lev);
    if (myrank == 0)
    {
@@ -485,7 +496,8 @@ void Z4c_class::Step(int lev, int YN)
  }
 #endif

-  Parallel::Sync(GH->PatL[lev], SynchList_pre, Symmetry);
+  // Complete async ghost zone exchange
+  if (sync_pre) Parallel::SyncEnd(sync_pre);

 #ifdef WithShell
  if (lev == 0)
@@ -693,13 +705,17 @@ void Z4c_class::Step(int lev, int YN)
      Pp = Pp->next;
    }

-    // check error information
+    // Start async ghost zone exchange - overlaps with error check and Shell computation
+    Parallel::SyncHandle *sync_cor = Parallel::SyncBeginWithPlan(sync_plan, SynchList_cor);
+
+    // check error information (overlaps with MPI transfer)
    {
      int erh = ERROR;
      MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
    }
    if (ERROR)
    {
+      Parallel::SyncEnd(sync_cor); sync_cor = 0;
      Parallel::Dump_Data(GH->PatL[lev], SynchList_pre, 0, PhysTime, dT_lev);
      if (myrank == 0)
      {
@@ -857,6 +873,7 @@ void Z4c_class::Step(int lev, int YN)
    }
    if (ERROR)
    {
+      Parallel::SyncEnd(sync_cor); sync_cor = 0;
      SH->Dump_Data(SynchList_pre, 0, PhysTime, dT_lev);
      if (myrank == 0)
      {
@@ -868,7 +885,8 @@ void Z4c_class::Step(int lev, int YN)
    }
 #endif

-    Parallel::Sync(GH->PatL[lev], SynchList_cor, Symmetry);
+    // Complete async ghost zone exchange
+    if (sync_cor) Parallel::SyncEnd(sync_cor);

 #ifdef WithShell
    if (lev == 0)
@@ -1042,6 +1060,8 @@ void Z4c_class::Step(int lev, int YN)
      Porg0[ithBH][2] = Porg1[ithBH][2];
    }
  }
+
+  Parallel::SyncFreePlan(sync_plan);
 }
 #else
 // for constraint preserving boundary (CPBC)
@@ -1075,6 +1095,10 @@ void Z4c_class::Step(int lev, int YN)
  int ERROR = 0;

  MyList<ss_patch> *sPp;
+
+  // Pre-build grid segment lists once for this level's patches.
+  Parallel::SyncPlan *sync_plan = Parallel::SyncPreparePlan(GH->PatL[lev], Symmetry);
+
  // Predictor
  MyList<Patch> *Pp = GH->PatL[lev];
  while (Pp)
@@ -1542,13 +1566,17 @@ void Z4c_class::Step(int lev, int YN)
  }
 #endif
  }
-  // check error information
+  // Start async ghost zone exchange - overlaps with error check
+  Parallel::SyncHandle *sync_pre = Parallel::SyncBeginWithPlan(sync_plan, SynchList_pre);
+
+  // check error information (overlaps with MPI transfer)
  {
    int erh = ERROR;
    MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
  }
  if (ERROR)
  {
+    Parallel::SyncEnd(sync_pre); sync_pre = 0;
    SH->Dump_Data(StateList, 0, PhysTime, dT_lev);
    if (myrank == 0)
    {
@@ -1558,7 +1586,8 @@ void Z4c_class::Step(int lev, int YN)
    }
  }

-  Parallel::Sync(GH->PatL[lev], SynchList_pre, Symmetry);
+  // Complete async ghost zone exchange
+  if (sync_pre) Parallel::SyncEnd(sync_pre);

  if (lev == 0)
  {
@@ -2103,13 +2132,17 @@ void Z4c_class::Step(int lev, int YN)
        sPp = sPp->next;
      }
    }
-    // check error information
+    // Start async ghost zone exchange - overlaps with error check
+    Parallel::SyncHandle *sync_cor = Parallel::SyncBeginWithPlan(sync_plan, SynchList_cor);
+
+    // check error information (overlaps with MPI transfer)
    {
      int erh = ERROR;
      MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
    }
    if (ERROR)
    {
+      Parallel::SyncEnd(sync_cor); sync_cor = 0;
      SH->Dump_Data(SynchList_pre, 0, PhysTime, dT_lev);
      if (myrank == 0)
      {
@@ -2120,7 +2153,8 @@ void Z4c_class::Step(int lev, int YN)
      }
    }

-    Parallel::Sync(GH->PatL[lev], SynchList_cor, Symmetry);
+    // Complete async ghost zone exchange
+    if (sync_cor) Parallel::SyncEnd(sync_cor);

    if (lev == 0)
    {
@@ -2346,6 +2380,8 @@ void Z4c_class::Step(int lev, int YN)
 	  DG_List->clearList();
 	}
 #endif
+
+  Parallel::SyncFreePlan(sync_plan);
 }
 #endif
 #undef MRBD
--- a/AMSS_NCKU_source/bssn_class.C
+++ b/AMSS_NCKU_source/bssn_class.C
@@ -3035,6 +3035,12 @@ void bssn_class::Step(int lev, int YN)
  int ERROR = 0;

  MyList<ss_patch> *sPp;
+
+  // Pre-build grid segment lists once for this level's patches.
+  // These are reused across predictor + 3 corrector SyncBegin calls,
+  // avoiding O(cpusize * blocks^2) rebuild each time.
+  Parallel::SyncPlan *sync_plan = Parallel::SyncPreparePlan(GH->PatL[lev], Symmetry);
+
  // Predictor
  MyList<Patch> *Pp = GH->PatL[lev];
  while (Pp)
@@ -3158,13 +3164,18 @@ void bssn_class::Step(int lev, int YN)
    }
    Pp = Pp->next;
  }
-  // check error information
+
+  // Start async ghost zone exchange - overlaps with error check and Shell computation
+  Parallel::SyncHandle *sync_pre = Parallel::SyncBeginWithPlan(sync_plan, SynchList_pre);
+
+  // check error information (overlaps with MPI transfer)
  {
    int erh = ERROR;
    MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
  }
  if (ERROR)
  {
+    Parallel::SyncEnd(sync_pre); sync_pre = 0;
    Parallel::Dump_Data(GH->PatL[lev], StateList, 0, PhysTime, dT_lev);
    if (myrank == 0)
    {
@@ -3324,6 +3335,7 @@ void bssn_class::Step(int lev, int YN)

  if (ERROR)
  {
+    Parallel::SyncEnd(sync_pre); sync_pre = 0;
    SH->Dump_Data(StateList, 0, PhysTime, dT_lev);
    if (myrank == 0)
    {
@@ -3334,7 +3346,8 @@ void bssn_class::Step(int lev, int YN)
  }
 #endif

-  Parallel::Sync(GH->PatL[lev], SynchList_pre, Symmetry);
+  // Complete async ghost zone exchange
+  if (sync_pre) Parallel::SyncEnd(sync_pre);

 #ifdef WithShell
  if (lev == 0)
@@ -3528,7 +3541,10 @@ void bssn_class::Step(int lev, int YN)
      Pp = Pp->next;
    }

-    // check error information
+    // Start async ghost zone exchange - overlaps with error check and Shell computation
+    Parallel::SyncHandle *sync_cor = Parallel::SyncBeginWithPlan(sync_plan, SynchList_cor);
+
+    // check error information (overlaps with MPI transfer)
    {
      int erh = ERROR;
      MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
@@ -3536,6 +3552,7 @@ void bssn_class::Step(int lev, int YN)

    if (ERROR)
    {
+      Parallel::SyncEnd(sync_cor); sync_cor = 0;
      Parallel::Dump_Data(GH->PatL[lev], SynchList_pre, 0, PhysTime, dT_lev);
      if (myrank == 0)
      {
@@ -3692,6 +3709,7 @@ void bssn_class::Step(int lev, int YN)
    }
    if (ERROR)
    {
+      Parallel::SyncEnd(sync_cor); sync_cor = 0;
      SH->Dump_Data(SynchList_pre, 0, PhysTime, dT_lev);
      if (myrank == 0)
      {
@@ -3704,7 +3722,8 @@ void bssn_class::Step(int lev, int YN)
    }
 #endif

-    Parallel::Sync(GH->PatL[lev], SynchList_cor, Symmetry);
+    // Complete async ghost zone exchange
+    if (sync_cor) Parallel::SyncEnd(sync_cor);

 #ifdef WithShell
    if (lev == 0)
@@ -3895,6 +3914,8 @@ void bssn_class::Step(int lev, int YN)
      Porg0[ithBH][2] = Porg1[ithBH][2];
    }
  }
+
+  Parallel::SyncFreePlan(sync_plan);
 }

 //================================================================================================
@@ -4817,6 +4838,12 @@ void bssn_class::Step(int lev, int YN)
  int ERROR = 0;

  MyList<ss_patch> *sPp;
+
+  // Pre-build grid segment lists once for this level's patches.
+  // These are reused across predictor + 3 corrector SyncBegin calls,
+  // avoiding O(cpusize * blocks^2) rebuild each time.
+  Parallel::SyncPlan *sync_plan = Parallel::SyncPreparePlan(GH->PatL[lev], Symmetry);
+
  // Predictor
  MyList<Patch> *Pp = GH->PatL[lev];
  while (Pp)
@@ -4943,13 +4970,17 @@ void bssn_class::Step(int lev, int YN)

  //   misc::tillherecheck(GH->Commlev[lev],GH->start_rank[lev],"after Predictor rhs calculation");

-  // check error information
+  // Start async ghost zone exchange - overlaps with error check and BH position
+  Parallel::SyncHandle *sync_pre = Parallel::SyncBeginWithPlan(sync_plan, SynchList_pre);
+
+  // check error information (overlaps with MPI transfer)
  {
    int erh = ERROR;
    MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, GH->Commlev[lev]);
  }
  if (ERROR)
  {
+    Parallel::SyncEnd(sync_pre); sync_pre = 0;
    Parallel::Dump_Data(GH->PatL[lev], StateList, 0, PhysTime, dT_lev);
    if (myrank == 0)
    {
@@ -4961,7 +4992,8 @@ void bssn_class::Step(int lev, int YN)

  //   misc::tillherecheck(GH->Commlev[lev],GH->start_rank[lev],"before Predictor sync");

-  Parallel::Sync(GH->PatL[lev], SynchList_pre, Symmetry);
+  // Complete async ghost zone exchange
+  if (sync_pre) Parallel::SyncEnd(sync_pre);

 #if (MAPBH == 0)
  // for black hole position
@@ -5140,13 +5172,17 @@ void bssn_class::Step(int lev, int YN)

    //   misc::tillherecheck(GH->Commlev[lev],GH->start_rank[lev],"before Corrector error check");

-    // check error information
+    // Start async ghost zone exchange - overlaps with error check and BH position
+    Parallel::SyncHandle *sync_cor = Parallel::SyncBeginWithPlan(sync_plan, SynchList_cor);
+
+    // check error information (overlaps with MPI transfer)
    {
      int erh = ERROR;
      MPI_Allreduce(&erh, &ERROR, 1, MPI_INT, MPI_SUM, GH->Commlev[lev]);
    }
    if (ERROR)
    {
+      Parallel::SyncEnd(sync_cor); sync_cor = 0;
      Parallel::Dump_Data(GH->PatL[lev], SynchList_pre, 0, PhysTime, dT_lev);
      if (myrank == 0)
      {
@@ -5160,7 +5196,8 @@ void bssn_class::Step(int lev, int YN)

    //    misc::tillherecheck(GH->Commlev[lev],GH->start_rank[lev],"before Corrector sync");

-    Parallel::Sync(GH->PatL[lev], SynchList_cor, Symmetry);
+    // Complete async ghost zone exchange
+    if (sync_cor) Parallel::SyncEnd(sync_cor);

    //    misc::tillherecheck(GH->Commlev[lev],GH->start_rank[lev],"after Corrector sync");

@@ -5276,6 +5313,8 @@ void bssn_class::Step(int lev, int YN)

  //     if(myrank==GH->start_rank[lev]) cout<<GH->mylev<<endl;
  //     misc::tillherecheck(GH->Commlev[lev],GH->start_rank[lev],"complet GH Step");
+
+  Parallel::SyncFreePlan(sync_plan);
 }

 //================================================================================================
--- a/AMSS_NCKU_source/bssn_rhs.f90
+++ b/AMSS_NCKU_source/bssn_rhs.f90
@@ -945,103 +945,60 @@
  SSA(2)=SYM
  SSA(3)=ANTI

-!!!!!!!!!advection term part
+!!!!!!!!!advection term + Kreiss-Oliger dissipation (merged for cache efficiency)
+! lopsided_kodis shares the symmetry_bd buffer between advection and
+! dissipation, eliminating redundant full-grid copies. For metric variables
+! gxx/gyy/gzz (=dxx/dyy/dzz+1): kodis stencil coefficients sum to zero,
+! so the constant offset has no effect on dissipation.

-  call lopsided(ex,X,Y,Z,gxx,gxx_rhs,betax,betay,betaz,Symmetry,SSS)
-  call lopsided(ex,X,Y,Z,gxy,gxy_rhs,betax,betay,betaz,Symmetry,AAS)
-  call lopsided(ex,X,Y,Z,gxz,gxz_rhs,betax,betay,betaz,Symmetry,ASA)
-  call lopsided(ex,X,Y,Z,gyy,gyy_rhs,betax,betay,betaz,Symmetry,SSS)
-  call lopsided(ex,X,Y,Z,gyz,gyz_rhs,betax,betay,betaz,Symmetry,SAA)
-  call lopsided(ex,X,Y,Z,gzz,gzz_rhs,betax,betay,betaz,Symmetry,SSS)
+  call lopsided_kodis(ex,X,Y,Z,gxx,gxx_rhs,betax,betay,betaz,Symmetry,SSS,eps)
+  call lopsided_kodis(ex,X,Y,Z,gxy,gxy_rhs,betax,betay,betaz,Symmetry,AAS,eps)
+  call lopsided_kodis(ex,X,Y,Z,gxz,gxz_rhs,betax,betay,betaz,Symmetry,ASA,eps)
+  call lopsided_kodis(ex,X,Y,Z,gyy,gyy_rhs,betax,betay,betaz,Symmetry,SSS,eps)
+  call lopsided_kodis(ex,X,Y,Z,gyz,gyz_rhs,betax,betay,betaz,Symmetry,SAA,eps)
+  call lopsided_kodis(ex,X,Y,Z,gzz,gzz_rhs,betax,betay,betaz,Symmetry,SSS,eps)

-  call lopsided(ex,X,Y,Z,Axx,Axx_rhs,betax,betay,betaz,Symmetry,SSS)
-  call lopsided(ex,X,Y,Z,Axy,Axy_rhs,betax,betay,betaz,Symmetry,AAS)
-  call lopsided(ex,X,Y,Z,Axz,Axz_rhs,betax,betay,betaz,Symmetry,ASA)
-  call lopsided(ex,X,Y,Z,Ayy,Ayy_rhs,betax,betay,betaz,Symmetry,SSS)
-  call lopsided(ex,X,Y,Z,Ayz,Ayz_rhs,betax,betay,betaz,Symmetry,SAA)
-  call lopsided(ex,X,Y,Z,Azz,Azz_rhs,betax,betay,betaz,Symmetry,SSS)
+  call lopsided_kodis(ex,X,Y,Z,Axx,Axx_rhs,betax,betay,betaz,Symmetry,SSS,eps)
+  call lopsided_kodis(ex,X,Y,Z,Axy,Axy_rhs,betax,betay,betaz,Symmetry,AAS,eps)
+  call lopsided_kodis(ex,X,Y,Z,Axz,Axz_rhs,betax,betay,betaz,Symmetry,ASA,eps)
+  call lopsided_kodis(ex,X,Y,Z,Ayy,Ayy_rhs,betax,betay,betaz,Symmetry,SSS,eps)
+  call lopsided_kodis(ex,X,Y,Z,Ayz,Ayz_rhs,betax,betay,betaz,Symmetry,SAA,eps)
+  call lopsided_kodis(ex,X,Y,Z,Azz,Azz_rhs,betax,betay,betaz,Symmetry,SSS,eps)

-  call lopsided(ex,X,Y,Z,chi,chi_rhs,betax,betay,betaz,Symmetry,SSS)
-  call lopsided(ex,X,Y,Z,trK,trK_rhs,betax,betay,betaz,Symmetry,SSS)
+  call lopsided_kodis(ex,X,Y,Z,chi,chi_rhs,betax,betay,betaz,Symmetry,SSS,eps)
+  call lopsided_kodis(ex,X,Y,Z,trK,trK_rhs,betax,betay,betaz,Symmetry,SSS,eps)

-  call lopsided(ex,X,Y,Z,Gamx,Gamx_rhs,betax,betay,betaz,Symmetry,ASS)
-  call lopsided(ex,X,Y,Z,Gamy,Gamy_rhs,betax,betay,betaz,Symmetry,SAS)
-  call lopsided(ex,X,Y,Z,Gamz,Gamz_rhs,betax,betay,betaz,Symmetry,SSA)
-!!
+  call lopsided_kodis(ex,X,Y,Z,Gamx,Gamx_rhs,betax,betay,betaz,Symmetry,ASS,eps)
+  call lopsided_kodis(ex,X,Y,Z,Gamy,Gamy_rhs,betax,betay,betaz,Symmetry,SAS,eps)
+  call lopsided_kodis(ex,X,Y,Z,Gamz,Gamz_rhs,betax,betay,betaz,Symmetry,SSA,eps)
+
+#if 1 
+!! bam does not apply dissipation on gauge variables
+  call lopsided_kodis(ex,X,Y,Z,Lap,Lap_rhs,betax,betay,betaz,Symmetry,SSS,eps)
+#if (GAUGE == 0 || GAUGE == 1 || GAUGE == 2 || GAUGE == 3 || GAUGE == 4 || GAUGE == 5 || GAUGE == 6 || GAUGE == 7)
+  call lopsided_kodis(ex,X,Y,Z,betax,betax_rhs,betax,betay,betaz,Symmetry,ASS,eps)
+  call lopsided_kodis(ex,X,Y,Z,betay,betay_rhs,betax,betay,betaz,Symmetry,SAS,eps)
+  call lopsided_kodis(ex,X,Y,Z,betaz,betaz_rhs,betax,betay,betaz,Symmetry,SSA,eps)
+#endif
+#if (GAUGE == 0 || GAUGE == 2 || GAUGE == 3 || GAUGE == 6 || GAUGE == 7)
+  call lopsided_kodis(ex,X,Y,Z,dtSfx,dtSfx_rhs,betax,betay,betaz,Symmetry,ASS,eps)
+  call lopsided_kodis(ex,X,Y,Z,dtSfy,dtSfy_rhs,betax,betay,betaz,Symmetry,SAS,eps)
+  call lopsided_kodis(ex,X,Y,Z,dtSfz,dtSfz_rhs,betax,betay,betaz,Symmetry,SSA,eps)
+#endif
+#else
+! No dissipation on gauge variables (advection only)
  call lopsided(ex,X,Y,Z,Lap,Lap_rhs,betax,betay,betaz,Symmetry,SSS)
-
 #if (GAUGE == 0 || GAUGE == 1 || GAUGE == 2 || GAUGE == 3 || GAUGE == 4 || GAUGE == 5 || GAUGE == 6 || GAUGE == 7)
  call lopsided(ex,X,Y,Z,betax,betax_rhs,betax,betay,betaz,Symmetry,ASS)
  call lopsided(ex,X,Y,Z,betay,betay_rhs,betax,betay,betaz,Symmetry,SAS)
  call lopsided(ex,X,Y,Z,betaz,betaz_rhs,betax,betay,betaz,Symmetry,SSA)
 #endif
-
 #if (GAUGE == 0 || GAUGE == 2 || GAUGE == 3 || GAUGE == 6 || GAUGE == 7)
  call lopsided(ex,X,Y,Z,dtSfx,dtSfx_rhs,betax,betay,betaz,Symmetry,ASS)
  call lopsided(ex,X,Y,Z,dtSfy,dtSfy_rhs,betax,betay,betaz,Symmetry,SAS)
  call lopsided(ex,X,Y,Z,dtSfz,dtSfz_rhs,betax,betay,betaz,Symmetry,SSA)
 #endif
-
-  if(eps>0)then 
-! usual Kreiss-Oliger dissipation      
-  call kodis(ex,X,Y,Z,chi,chi_rhs,SSS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,trK,trK_rhs,SSS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,dxx,gxx_rhs,SSS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,gxy,gxy_rhs,AAS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,gxz,gxz_rhs,ASA,Symmetry,eps)
-  call kodis(ex,X,Y,Z,dyy,gyy_rhs,SSS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,gyz,gyz_rhs,SAA,Symmetry,eps)
-  call kodis(ex,X,Y,Z,dzz,gzz_rhs,SSS,Symmetry,eps)
-#if 0
-#define i 42
-#define j 40
-#define k 40
-if(Lev == 1)then
-write(*,*) X(i),Y(j),Z(k)
-write(*,*) "before",Axx_rhs(i,j,k)
-endif
-#undef i
-#undef j
-#undef k
-!!stop
 #endif
-  call kodis(ex,X,Y,Z,Axx,Axx_rhs,SSS,Symmetry,eps)
-#if 0
-#define i 42
-#define j 40
-#define k 40
-if(Lev == 1)then
-write(*,*) X(i),Y(j),Z(k)
-write(*,*) "after",Axx_rhs(i,j,k)
-endif
-#undef i
-#undef j
-#undef k
-!!stop
-#endif
-  call kodis(ex,X,Y,Z,Axy,Axy_rhs,AAS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,Axz,Axz_rhs,ASA,Symmetry,eps)
-  call kodis(ex,X,Y,Z,Ayy,Ayy_rhs,SSS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,Ayz,Ayz_rhs,SAA,Symmetry,eps)
-  call kodis(ex,X,Y,Z,Azz,Azz_rhs,SSS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,Gamx,Gamx_rhs,ASS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,Gamy,Gamy_rhs,SAS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,Gamz,Gamz_rhs,SSA,Symmetry,eps)
-
-#if 1 
-!! bam does not apply dissipation on gauge variables
-  call kodis(ex,X,Y,Z,Lap,Lap_rhs,SSS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,betax,betax_rhs,ASS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,betay,betay_rhs,SAS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,betaz,betaz_rhs,SSA,Symmetry,eps)
-#if (GAUGE == 0 || GAUGE == 2 || GAUGE == 3 || GAUGE == 6 || GAUGE == 7)
-  call kodis(ex,X,Y,Z,dtSfx,dtSfx_rhs,ASS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,dtSfy,dtSfy_rhs,SAS,Symmetry,eps)
-  call kodis(ex,X,Y,Z,dtSfz,dtSfz_rhs,SSA,Symmetry,eps)
-#endif
-#endif
-
-  endif

  if(co == 0)then
 ! ham_Res = trR + 2/3 * K^2 - A_ij * A^ij - 16 * PI * rho
--- a/AMSS_NCKU_source/lopsidediff.f90
+++ b/AMSS_NCKU_source/lopsidediff.f90
@@ -487,6 +487,201 @@ subroutine lopsided(ex,X,Y,Z,f,f_rhs,Sfx,Sfy,Sfz,Symmetry,SoA)

  end subroutine lopsided

+!-----------------------------------------------------------------------------
+! Combined advection (lopsided) + Kreiss-Oliger dissipation (kodis)
+! Shares the symmetry_bd buffer fh, eliminating one full-grid copy per call.
+! Mathematically identical to calling lopsided then kodis separately.
+!-----------------------------------------------------------------------------
+subroutine lopsided_kodis(ex,X,Y,Z,f,f_rhs,Sfx,Sfy,Sfz,Symmetry,SoA,eps)
+  implicit none
+
+!~~~~~~> Input parameters:
+
+  integer, intent(in)  :: ex(1:3),Symmetry
+  real*8,  intent(in)  :: X(1:ex(1)),Y(1:ex(2)),Z(1:ex(3))
+  real*8,dimension(ex(1),ex(2),ex(3)),intent(in)   :: f,Sfx,Sfy,Sfz
+
+  real*8,dimension(ex(1),ex(2),ex(3)),intent(inout):: f_rhs
+  real*8,dimension(3),intent(in) ::SoA
+  real*8,intent(in) :: eps
+
+!~~~~~~> local variables:
+! note index -2,-1,0, so we have 3 extra points
+  real*8,dimension(-2:ex(1),-2:ex(2),-2:ex(3))   :: fh
+  integer :: imin,jmin,kmin,imax,jmax,kmax,i,j,k
+  real*8 :: dX,dY,dZ
+  real*8 :: d12dx,d12dy,d12dz,d2dx,d2dy,d2dz
+  real*8,  parameter :: ZEO=0.d0,ONE=1.d0, F3=3.d0
+  real*8,  parameter :: TWO=2.d0,F6=6.0d0,F18=1.8d1
+  real*8,  parameter :: F12=1.2d1, F10=1.d1,EIT=8.d0
+  integer, parameter :: NO_SYMM = 0, EQ_SYMM = 1, OCTANT = 2
+! kodis parameters
+  real*8, parameter :: SIX=6.d0,FIT=1.5d1,TWT=2.d1
+  real*8, parameter :: cof=6.4d1   ! 2^6
+
+  dX = X(2)-X(1)
+  dY = Y(2)-Y(1)
+  dZ = Z(2)-Z(1)
+
+  d12dx = ONE/F12/dX
+  d12dy = ONE/F12/dY
+  d12dz = ONE/F12/dZ
+
+  d2dx = ONE/TWO/dX
+  d2dy = ONE/TWO/dY
+  d2dz = ONE/TWO/dZ
+
+  imax = ex(1)
+  jmax = ex(2)
+  kmax = ex(3)
+
+  imin = 1
+  jmin = 1
+  kmin = 1
+  if(Symmetry > NO_SYMM .and. dabs(Z(1)) < dZ) kmin = -2
+  if(Symmetry > EQ_SYMM .and. dabs(X(1)) < dX) imin = -2
+  if(Symmetry > EQ_SYMM .and. dabs(Y(1)) < dY) jmin = -2
+
+! Single symmetry_bd call shared by both advection and dissipation
+  call symmetry_bd(3,ex,f,fh,SoA)
+
+! ---- Advection (lopsided) loop ----
+! upper bound set ex-1 only for efficiency, 
+! the loop body will set ex 0 also
+  do k=1,ex(3)-1
+  do j=1,ex(2)-1
+  do i=1,ex(1)-1
+! x direction   
+    if(Sfx(i,j,k) > ZEO)then
+      if(i+3 <= imax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                   &
+                  Sfx(i,j,k)*d12dx*(-F3*fh(i-1,j,k)-F10*fh(i,j,k)+F18*fh(i+1,j,k) &
+                                    -F6*fh(i+2,j,k)+    fh(i+3,j,k))
+     elseif(i+2 <= imax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                           &
+                  Sfx(i,j,k)*d12dx*(fh(i-2,j,k)-EIT*fh(i-1,j,k)+EIT*fh(i+1,j,k)-fh(i+2,j,k))
+
+     elseif(i+1 <= imax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)-                                                   &
+                  Sfx(i,j,k)*d12dx*(-F3*fh(i+1,j,k)-F10*fh(i,j,k)+F18*fh(i-1,j,k) &
+                                    -F6*fh(i-2,j,k)+    fh(i-3,j,k))
+     endif
+   elseif(Sfx(i,j,k) < ZEO)then
+      if(i-3 >= imin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)-                                                   &
+                  Sfx(i,j,k)*d12dx*(-F3*fh(i+1,j,k)-F10*fh(i,j,k)+F18*fh(i-1,j,k) &
+                                    -F6*fh(i-2,j,k)+    fh(i-3,j,k))
+     elseif(i-2 >= imin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                           &
+                  Sfx(i,j,k)*d12dx*(fh(i-2,j,k)-EIT*fh(i-1,j,k)+EIT*fh(i+1,j,k)-fh(i+2,j,k))
+
+     elseif(i-1 >= imin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                   &
+                  Sfx(i,j,k)*d12dx*(-F3*fh(i-1,j,k)-F10*fh(i,j,k)+F18*fh(i+1,j,k) &
+                                    -F6*fh(i+2,j,k)+    fh(i+3,j,k))
+     endif
+   endif
+
+! y direction   
+    if(Sfy(i,j,k) > ZEO)then
+      if(j+3 <= jmax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                   &
+                  Sfy(i,j,k)*d12dy*(-F3*fh(i,j-1,k)-F10*fh(i,j,k)+F18*fh(i,j+1,k) &
+                                    -F6*fh(i,j+2,k)+    fh(i,j+3,k))
+     elseif(j+2 <= jmax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                           &
+                  Sfy(i,j,k)*d12dy*(fh(i,j-2,k)-EIT*fh(i,j-1,k)+EIT*fh(i,j+1,k)-fh(i,j+2,k))
+
+     elseif(j+1 <= jmax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)-                                                   &
+                  Sfy(i,j,k)*d12dy*(-F3*fh(i,j+1,k)-F10*fh(i,j,k)+F18*fh(i,j-1,k) &
+                                    -F6*fh(i,j-2,k)+    fh(i,j-3,k))
+     endif
+   elseif(Sfy(i,j,k) < ZEO)then
+      if(j-3 >= jmin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)-                                                   &
+                  Sfy(i,j,k)*d12dy*(-F3*fh(i,j+1,k)-F10*fh(i,j,k)+F18*fh(i,j-1,k) &
+                                    -F6*fh(i,j-2,k)+    fh(i,j-3,k))
+     elseif(j-2 >= jmin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                           &
+                  Sfy(i,j,k)*d12dy*(fh(i,j-2,k)-EIT*fh(i,j-1,k)+EIT*fh(i,j+1,k)-fh(i,j+2,k))
+
+     elseif(j-1 >= jmin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                   &
+                  Sfy(i,j,k)*d12dy*(-F3*fh(i,j-1,k)-F10*fh(i,j,k)+F18*fh(i,j+1,k) &
+                                    -F6*fh(i,j+2,k)+    fh(i,j+3,k))
+     endif
+   endif
+
+! z direction   
+    if(Sfz(i,j,k) > ZEO)then
+      if(k+3 <= kmax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                   &
+                  Sfz(i,j,k)*d12dz*(-F3*fh(i,j,k-1)-F10*fh(i,j,k)+F18*fh(i,j,k+1) &
+                                    -F6*fh(i,j,k+2)+    fh(i,j,k+3))
+     elseif(k+2 <= kmax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                           &
+                  Sfz(i,j,k)*d12dz*(fh(i,j,k-2)-EIT*fh(i,j,k-1)+EIT*fh(i,j,k+1)-fh(i,j,k+2))
+
+     elseif(k+1 <= kmax)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)-                                                   &
+                  Sfz(i,j,k)*d12dz*(-F3*fh(i,j,k+1)-F10*fh(i,j,k)+F18*fh(i,j,k-1) &
+                                    -F6*fh(i,j,k-2)+    fh(i,j,k-3))
+     endif
+   elseif(Sfz(i,j,k) < ZEO)then
+      if(k-3 >= kmin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)-                                                   &
+                  Sfz(i,j,k)*d12dz*(-F3*fh(i,j,k+1)-F10*fh(i,j,k)+F18*fh(i,j,k-1) &
+                                    -F6*fh(i,j,k-2)+    fh(i,j,k-3))
+     elseif(k-2 >= kmin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                           &
+                  Sfz(i,j,k)*d12dz*(fh(i,j,k-2)-EIT*fh(i,j,k-1)+EIT*fh(i,j,k+1)-fh(i,j,k+2))
+
+     elseif(k-1 >= kmin)then
+     f_rhs(i,j,k)=f_rhs(i,j,k)+                                                   &
+                  Sfz(i,j,k)*d12dz*(-F3*fh(i,j,k-1)-F10*fh(i,j,k)+F18*fh(i,j,k+1) &
+                                    -F6*fh(i,j,k+2)+    fh(i,j,k+3))
+     endif
+   endif
+  enddo
+  enddo
+  enddo
+
+! ---- Dissipation (kodis) loop ----
+  if(eps > ZEO) then
+  do k=1,ex(3)
+  do j=1,ex(2)
+  do i=1,ex(1)
+
+  if(i-3 >= imin .and. i+3 <= imax .and. &
+     j-3 >= jmin .and. j+3 <= jmax .and. &
+     k-3 >= kmin .and. k+3 <= kmax) then
+   f_rhs(i,j,k)       = f_rhs(i,j,k) + eps/cof *( (     &
+                              (fh(i-3,j,k)+fh(i+3,j,k)) - &
+                          SIX*(fh(i-2,j,k)+fh(i+2,j,k)) + &
+                          FIT*(fh(i-1,j,k)+fh(i+1,j,k)) - &
+                          TWT* fh(i,j,k)            )/dX + &
+                                                  (     &
+                              (fh(i,j-3,k)+fh(i,j+3,k)) - &
+                          SIX*(fh(i,j-2,k)+fh(i,j+2,k)) + &
+                          FIT*(fh(i,j-1,k)+fh(i,j+1,k)) - &
+                          TWT* fh(i,j,k)            )/dY + &
+                                                  (     &
+                              (fh(i,j,k-3)+fh(i,j,k+3)) - &
+                          SIX*(fh(i,j,k-2)+fh(i,j,k+2)) + &
+                          FIT*(fh(i,j,k-1)+fh(i,j,k+1)) - &
+                          TWT* fh(i,j,k)            )/dZ )
+  endif
+
+  enddo
+  enddo
+  enddo
+  endif
+
+  return
+
+  end subroutine lopsided_kodis
+
 #elif (ghost_width == 4)
 ! sixth order code
 ! Compute advection terms in right hand sides of field equations
--- a/parallel_plot_helper.py
+++ b/parallel_plot_helper.py
@@ -0,0 +1,29 @@
+import multiprocessing
+
+def run_plot_task(task):
+    """Execute a single plotting task.
+    
+    Parameters
+    ----------
+    task : tuple
+        A tuple of (function, args_tuple) where function is a callable
+        plotting function and args_tuple contains its arguments.
+    """
+    func, args = task
+    return func(*args)
+
+
+def run_plot_tasks_parallel(plot_tasks):
+    """Execute a list of independent plotting tasks in parallel.
+
+    Uses the 'fork' context to create worker processes so that the main
+    script is NOT re-imported/re-executed in child processes.
+
+    Parameters
+    ----------
+    plot_tasks : list of tuples
+        Each element is (function, args_tuple).
+    """
+    ctx = multiprocessing.get_context('fork')
+    with ctx.Pool() as pool:
+        pool.map(run_plot_task, plot_tasks)
--- a/plot_GW_strain_amplitude_xiaoqu.py
+++ b/plot_GW_strain_amplitude_xiaoqu.py
@@ -11,6 +11,8 @@
 import numpy                               ## numpy for array operations
 import scipy                               ## scipy for interpolation and signal processing
 import math
+import matplotlib
+matplotlib.use('Agg')                      ## use non-interactive backend for multiprocessing safety
 import matplotlib.pyplot    as     plt     ## matplotlib for plotting
 import os                                  ## os for system/file operations

--- a/plot_binary_data.py
+++ b/plot_binary_data.py
@@ -8,16 +8,23 @@
 ##
 #################################################

+## Restrict OpenMP to one thread per process so that running
+## many workers in parallel does not create an O(workers * BLAS_threads)
+## thread explosion.  The variable MUST be set before numpy/scipy
+## are imported, because the BLAS library reads them only at load time.
+import os
+os.environ.setdefault("OMP_NUM_THREADS",        "1")
+
 import numpy
 import scipy
+import matplotlib
+matplotlib.use('Agg')                      ## use non-interactive backend for multiprocessing safety
 import matplotlib.pyplot    as     plt
 from   matplotlib.colors    import LogNorm
 from   mpl_toolkits.mplot3d import Axes3D
 ## import torch
 import AMSS_NCKU_Input      as input_data

-import os
-

 #########################################################################################

@@ -192,3 +199,19 @@ def get_data_xy( Rmin, Rmax, n, data0, time, figure_title, figure_outdir ):

 ####################################################################################

+
+####################################################################################
+## Allow this module to be run as a standalone script so that each
+## binary-data plot can be executed in a fresh subprocess whose BLAS
+## environment variables (set above) take effect before numpy loads.
+##
+## Usage:  python3 plot_binary_data.py <filename> <binary_outdir> <figure_outdir>
+####################################################################################
+
+if __name__ == '__main__':
+    import sys
+    if len(sys.argv) != 4:
+        print(f"Usage: {sys.argv[0]} <filename> <binary_outdir> <figure_outdir>")
+        sys.exit(1)
+    plot_binary_data(sys.argv[1], sys.argv[2], sys.argv[3])
+
--- a/plot_xiaoqu.py
+++ b/plot_xiaoqu.py
@@ -8,6 +8,8 @@
 #################################################

 import numpy                               ## numpy for array operations
+import matplotlib
+matplotlib.use('Agg')                      ## use non-interactive backend for multiprocessing safety
 import matplotlib.pyplot    as     plt     ## matplotlib for plotting
 from   mpl_toolkits.mplot3d import Axes3D  ## needed for 3D plots
 import glob
@@ -15,6 +17,9 @@ import os                                  ## operating system utilities

 import plot_binary_data
 import AMSS_NCKU_Input as input_data
+import subprocess
+import sys
+import multiprocessing

 # plt.rcParams['text.usetex'] = True  ## enable LaTeX fonts in plots

@@ -50,10 +55,40 @@ def generate_binary_data_plot( binary_outdir, figure_outdir ):
        file_list.append(x)
        print(x)

-    ## Plot each file in the list
+    ## Plot each file in parallel using subprocesses.
+    ## Each subprocess is a fresh Python process where the BLAS thread-count
+    ## environment variables (set at the top of plot_binary_data.py) take
+    ## effect before numpy is imported.  This avoids the thread explosion
+    ## that occurs when multiprocessing.Pool with 'fork' context inherits
+    ## already-initialized multi-threaded BLAS from the parent.
+    script = os.path.join( os.path.dirname(__file__), "plot_binary_data.py" )
+    max_workers = min( multiprocessing.cpu_count(), len(file_list) ) if file_list else 0
+
+    running = []
+    failed  = []
    for filename in file_list:
        print(filename)
-        plot_binary_data.plot_binary_data(filename, binary_outdir, figure_outdir)
+        proc = subprocess.Popen(
+            [sys.executable, script, filename, binary_outdir, figure_outdir],
+        )
+        running.append( (proc, filename) )
+        ## Keep at most max_workers subprocesses active at a time
+        if len(running) >= max_workers:
+            p, fn = running.pop(0)
+            p.wait()
+            if p.returncode != 0:
+                failed.append(fn)
+
+    ## Wait for all remaining subprocesses to finish
+    for p, fn in running:
+        p.wait()
+        if p.returncode != 0:
+            failed.append(fn)
+
+    if failed:
+        print( " WARNING: the following binary data plots failed:" )
+        for fn in failed:
+            print( "   ", fn )

    print(                        )
    print( " Binary Data Plot Has been Finished " )
Author	SHA1	Message	Date
ianchb	8b68b5d782	fixup! Fix load explosion: use subprocess for binary data plots to avoid thread conflict * Seems we don't have to set so many variables, `OMP_NUM_THREADS` is enough. Test: Annotate the code for setting other environment variables. It runs normally.	2026-02-09 23:00:17 +08:00
ianchb	dd2443c926	Fix load explosion: use subprocess for binary data plots to avoid thread conflict Co-authored-by: copilot-swe-agent[bot] <198982749+copilot@users.noreply.github.com>	2026-02-09 21:40:27 +08:00
ianchb	2d7ba5c60c	[2/2] Implement multiprocessing-based parallel plotting	2026-02-09 21:36:45 +08:00
ianchb	4777cad4ed	[1/2] Implement multiprocessing-based parallel plotting	2026-02-09 15:13:18 +08:00
ianchb	afd4006da2	Cache GSL in SyncPlan and apply async Sync to Z4c_class Major optimization: Pre-build grid segment lists (GSLs) once per Step() call via SyncPreparePlan(), then reuse them across all 4 RK4 substep SyncBegin calls via SyncBeginWithPlan(). This eliminates the O(cpusize * blocks^2) GSL rebuild cost that was incurred on every ghost zone exchange. Applied async SyncBegin/SyncEnd overlap pattern to Z4c_class.C (ABEtype==2, the default configuration), which was still using blocking Parallel::Sync. Both the regular and CPBC variants of Z4c Step() are now optimized. Co-authored-by: copilot-swe-agent[bot] <198982749+copilot@users.noreply.github.com>	2026-02-08 16:46:44 +08:00
copilot-swe-agent[bot]	a918dc103e	Add SyncBegin/SyncEnd to Parallel for MPI communication-computation overlap Split the blocking Parallel::Sync into async SyncBegin (initiates local copy + MPI_Isend/Irecv) and SyncEnd (MPI_Waitall + unpack). This allows overlapping MPI ghost zone exchange with error checking and Shell patch computation. Modified Step() in bssn_class.C for both PSTR==0 and PSTR==1/2/3 versions to start Sync before error checks, overlapping the MPI_Allreduce with the ongoing ghost zone transfers. Co-authored-by: copilot-swe-agent[bot] <198982749+copilot@users.noreply.github.com>	2026-02-08 16:19:13 +08:00
copilot-swe-agent[bot]	38c2c30186	Merge lopsided advection + kodis dissipation to share symmetry_bd buffer Add lopsided_kodis subroutine in lopsidediff.f90 that combines upwind advection (lopsided) and Kreiss-Oliger dissipation (kodis) into one function sharing a single fh buffer from symmetry_bd. This eliminates 27 redundant full-grid copies per RHS evaluation (108 per timestep). For gxx/gyy/gzz variables: kodis stencil coefficients sum to zero (1-6+15-20+15-6+1=0), so using gxx(=dxx+1) instead of dxx for the dissipation buffer is mathematically exact. Update bssn_rhs.f90 to use the merged lopsided_kodis calls. Co-authored-by: ianchb <45872450+ianchb@users.noreply.github.com>	2026-02-08 15:42:44 +08:00