15.mpi_tag_ub.patch

diff --git a/src/globals.cpp b/src/globals.cpp
index 5d12815a..1f2271fb 100644
--- a/src/globals.cpp
+++ b/src/globals.cpp
@@ -22,6 +22,7 @@ namespace Globals {
 // all of these global variables are set at the start of main():
 int my_rank;         // MPI rank of this process
 int nranks;          // total number of MPI ranks
+int mpi_tag_ub;		// upper bound on MPI tags
 int next_task_id = 69;  // next available task id (last item of task_list)
 int next_scalar_index = 0;  // next available scalar index
 }
diff --git a/src/globals.hpp b/src/globals.hpp
index 885ef30b..1687063b 100644
--- a/src/globals.hpp
+++ b/src/globals.hpp
@@ -12,6 +12,7 @@ namespace Globals {
 extern int my_rank, nranks;
 extern int next_task_id;
 extern int next_scalar_index;
+extern int mpi_tag_ub;
 }
 
 #endif // GLOBALS_HPP_
diff --git a/src/main.cpp b/src/main.cpp
index 04d74465..b0381d00 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -109,6 +109,13 @@ int main(int argc, char *argv[]) {
     MPI_Finalize();
     return(0);
   }
+
+  // Get maximum value of MPI tag
+  MPI_Aint* tag_ub_ptr;
+  int att_flag;
+  MPI_Comm_get_attr(MPI_COMM_WORLD, MPI_TAG_UB, &tag_ub_ptr, &att_flag);
+  Globals::mpi_tag_ub = *tag_ub_ptr;
+  
 #else  // no MPI
   Globals::my_rank = 0;
   Globals::nranks  = 1;