fix parallel .vtu missing footer

diff --git a/source/base/data_out_base.cc b/source/base/data_out_base.cc
index bfa770c2eba7c7a3f8de4e861e8821a796f9aac7..a7bbb7d98ceef4e820cccb0e1f0b27fc33d31cd4 100644 (file)
--- a/source/base/data_out_base.cc
+++ b/source/base/data_out_base.cc
@@ -7786,6 +7786,11 @@ DataOutInterface<dim, spacedim>::write_vtu_in_parallel(
       }
   }
 
+  // Make sure we sync to disk. This ensures that the change in file
+  // size caused by the write_at() for the footer is visible for all
+  // ranks. Otherwise, the footer is sometimes lost.
+  ierr = MPI_File_sync(fh);
+  AssertThrowMPI(ierr);
 
   ierr = MPI_File_close(&fh);
   AssertThrowMPI(ierr);