Made sc_finalize optional.

src/auxiliary/t8code.jl

@@ -13,8 +13,8 @@ function init_t8code()
     end
 
     # Initialize the sc library, has to happen before we initialize t8code.
-    let catch_signals = 0, print_backtrace = 0
-        T8code.Libt8.sc_init(mpi_comm(), catch_signals, print_backtrace, C_NULL,
+    let catch_signals = 0, print_backtrace = 0, log_handler = C_NULL
+        T8code.Libt8.sc_init(mpi_comm(), catch_signals, print_backtrace, log_handler,
                              T8code.Libt8.SC_LP_ERROR)
     end
 
@@ -26,10 +26,16 @@ function init_t8code()
     # Initialize t8code with log level ERROR to prevent a lot of output in AMR simulations.
     t8_init(T8code.Libt8.SC_LP_ERROR)
 
-    # `sc_finalize` should always be called during shutdown of an application.
-    # It checks whether there is still un-freed memory by t8code and/or
-    # T8code.jl and throws an exception if this is the case.
-    MPI.add_finalize_hook!(T8code.Libt8.sc_finalize)
+    if haskey(ENV, "TRIXI_T8CODE_SC_FINALIZE")
+        # Normally, `sc_finalize` should always be called during shutdown of an
+        # application. It checks whether there is still un-freed memory by t8code
+        # and/or T8code.jl and throws an exception if this is the case. For
+        # production runs this is not mandatory, but is helpful during
+        # development. Hence, this option is only activated when environment
+        # variable TRIXI_T8CODE_SC_FINALIZE exists.
+        @warn "T8code.jl: sc_finalize will be called during shutdown of Trixi.jl."
+        MPI.add_finalize_hook!(T8code.Libt8.sc_finalize)
+    end
 
     return nothing
 end

src/meshes/t8code_mesh.jl

@@ -46,19 +46,24 @@ mutable struct T8codeMesh{NDIMS, RealT <: Real, IsParallel, NDIMSP2, NNODES} <:
             # `cmesh` does some MPI calls for deallocating shared memory
             # arrays. Due to garbage collection in Julia the order of shutdown
             # is not deterministic. The following code might happen after MPI
-            # is already in finalized state. In this case the `finalize_hook`
-            # of the MPI module already took care of the cleanup. See further
-            # down.
+            # is already in finalized state.
+            # If the environment variable `TRIXI_T8CODE_SC_FINALIZE` is set the
+            # `finalize_hook` of the MPI module takes care of the cleanup. See
+            # further down. However, this might cause a pile-up of `mesh`
+            # objects during long-running sessions.
             if !MPI.Finalized()
                 trixi_t8_unref_forest(mesh.forest)
             end
         end
 
-        MPI.add_finalize_hook!() do
-            try
+        # This finalizer call is only recommended during development and not for
+        # production runs, especially long-running sesions since a reference to
+        # the `mesh` object will be kept throughout the lifetime of the session.
+        # See comments in `init_t8code()` in file `src/auxiliary/t8code.jl` for
+        # more information.
+        if haskey(ENV, "TRIXI_T8CODE_SC_FINALIZE")
+            MPI.add_finalize_hook!() do
                 trixi_t8_unref_forest(mesh.forest)
-            catch
-                # The `mesh` object was already finalized. Do nothing.
             end
         end