fix hang on restart when multiple nodes, gas, and MaxFilesWithConcurrentIO != 0 is used

src/io/restart.cc

@@ -298,6 +298,9 @@ void restart::work_files(int modus)
 
   MPI_Gather(&seq_loc, sizeof(seq_data), MPI_BYTE, seq, sizeof(seq_data), MPI_BYTE, 0, Communicator);
 
+  if(modus == MODUS_READ)
+    MPI_Comm_split(Communicator, Shmem.Island_Smallest_WorldTask, 0, &Sim->NgbTree.TreeSharedMemComm);
+
   if(ThisTask == 0)
     {
       std::sort(seq, seq + NTask);
@@ -357,6 +360,9 @@ void restart::work_files(int modus)
       /* send back completion notice */
       MPI_Ssend(&ThisTask, 1, MPI_INT, 0, TAG_KEY, Communicator);
     }
+
+  if(modus == MODUS_READ)
+    Sim->NgbTree.treeallocate_share_topnode_addresses();
 }
 
 void restart::contents_restart_file(int modus)
@@ -523,12 +529,16 @@ void restart::contents_restart_file(int modus)
     {
       byten(Sim->NgbTree.Nodes + Sim->NgbTree.MaxPart + Sim->Domain.NTopnodes,
             (Sim->NgbTree.NumNodes - Sim->Domain.NTopnodes) * sizeof(ngbnode), modus);
+      byten(Sim->NgbTree.Nextnode, (Sim->NgbTree.MaxPart + Sim->Domain.NTopleaves) * sizeof(int), modus);
+      byten(Sim->NgbTree.Father, Sim->NgbTree.MaxPart * sizeof(int), modus);
+
+      if(Sim->NgbTree.TreeSharedMem_ThisTask == 0)
+        {
           byten(Sim->NgbTree.TopNodes + Sim->NgbTree.MaxPart, Sim->Domain.NTopnodes * sizeof(ngbnode), modus);
           byten(Sim->NgbTree.NodeIndex, Sim->Domain.NTopleaves * sizeof(int), modus);
           byten(Sim->NgbTree.NodeSibling, Sim->Domain.NTopleaves * sizeof(int), modus);
           byten(Sim->NgbTree.NodeLevel, Sim->Domain.NTopleaves * sizeof(unsigned char), modus);
-      byten(Sim->NgbTree.Nextnode, (Sim->NgbTree.MaxPart + Sim->Domain.NTopleaves) * sizeof(int), modus);
-      byten(Sim->NgbTree.Father, Sim->NgbTree.MaxPart * sizeof(int), modus);
+        }
     }
 
   byten(Sim->Domain.TopNodes, Sim->Domain.NTopnodes * Sim->Domain.domain_sizeof_topnode_data(), modus);

src/tree/tree.cc

@@ -778,10 +778,12 @@ void tree<node, partset, point_data, foreign_point_data>::treeallocate(int max_p
   D  = Dptr;
   Tp = Tp_ptr;
 
+  /* split up the communicator into pieces overlap with different shared memory regions */
+  if(max_partindex != -1)
+    MPI_Comm_split(D->Communicator, Shmem.Island_Smallest_WorldTask, 0, &TreeSharedMemComm);
+
   if(max_partindex != -1)
-    {
     MPI_Allreduce(&max_partindex, &MaxPart, 1, MPI_INT, MPI_MAX, D->Communicator);
-    }
 
   if(MaxPart == 0)
     return;  // nothing to be done
@@ -816,9 +818,6 @@ void tree<node, partset, point_data, foreign_point_data>::treeallocate(int max_p
       max_partindex = MaxPart;
     }
 
-  /* now split up the communicator into pieces overlap with different shared memory regions */
-  MPI_Comm_split(D->Communicator, Shmem.Island_Smallest_WorldTask, 0, &TreeSharedMemComm);
-
   MPI_Comm_rank(TreeSharedMemComm, &TreeSharedMem_ThisTask);
   MPI_Comm_size(TreeSharedMemComm, &TreeSharedMem_NTask);
 
@@ -880,6 +879,16 @@ void tree<node, partset, point_data, foreign_point_data>::treeallocate(int max_p
         }
     }
 
+  Nodes = (node *)Mem.mymalloc_movable(&Nodes, "Nodes", (MaxNodes - D->NTopnodes + 1) * sizeof(node));
+  Nodes -= (MaxPart + D->NTopnodes);
+
+  if(max_partindex != -1)
+    treeallocate_share_topnode_addresses();
+}
+
+template <typename node, typename partset, typename point_data, typename foreign_point_data>
+void tree<node, partset, point_data, foreign_point_data>::treeallocate_share_topnode_addresses(void)
+{
   MPI_Bcast(&TreeInfoHandle, 1, MPI_INT, 0, TreeSharedMemComm);
 
   ptrdiff_t off[4] = {((char *)NodeLevel - Mem.Base), ((char *)NodeSibling - Mem.Base), ((char *)NodeIndex - Mem.Base),
@@ -894,9 +903,6 @@ void tree<node, partset, point_data, foreign_point_data>::treeallocate(int max_p
   NodeSibling = (int *)((char *)Shmem.SharedMemBaseAddr[shmrank] + off[1]);
   NodeIndex   = (int *)((char *)Shmem.SharedMemBaseAddr[shmrank] + off[2]);
   TopNodes    = (node *)((char *)Shmem.SharedMemBaseAddr[shmrank] + off[3]);
-
-  Nodes = (node *)Mem.mymalloc_movable(&Nodes, "Nodes", (MaxNodes - D->NTopnodes + 1) * sizeof(node));
-  Nodes -= (MaxPart + D->NTopnodes);
 }
 
 template <typename node, typename partset, typename point_data, typename foreign_point_data>
@@ -1221,13 +1227,13 @@ void tree<node, partset, point_data, foreign_point_data>::tree_fetch_foreign_nod
 template <typename node, typename partset, typename point_data, typename foreign_point_data>
 void tree<node, partset, point_data, foreign_point_data>::treefree(void)
 {
+  MPI_Comm_free(&TreeSharedMemComm);
+
   if(MaxPart == 0)
     return;  // nothing to be done
 
   if(Nodes)
     {
-      MPI_Comm_free(&TreeSharedMemComm);
-
       if(Father)
         {
           Mem.myfree_movable(Father);

src/tree/tree.h

@@ -321,6 +321,7 @@ class tree
   int treebuild(int ninsert, int *indexlist);
   void treefree(void);
   void treeallocate(int max_partindex, partset *Pptr, domain<partset> *Dptr);
+  void treeallocate_share_topnode_addresses(void);
 
   void tree_export_node_threads(int no, int i, thread_data *thread, offset_tuple off = 0);
   void tree_export_node_threads_by_task_and_node(int task, int nodeindex, int i, thread_data *thread, offset_tuple off = 0);