[Fix] ProfileMonitor

Set hdf5 file to "a" mode fix an issue where the ProfileMonitor in MPI mode hung when writing data.
Remove flushing in ProfileMonitor.write() to avoid hung issuse in MPI mode.

mbtrack2/tracking/monitors/monitors.py

@@ -121,10 +121,10 @@ class Monitor(Element, metaclass=ABCMeta):
                 if len(self._file_storage) == 0:
                     if mpi_mode == True:
                         from mpi4py import MPI
-                        f = hp.File(self.file_name, "w", libver='earliest', 
+                        f = hp.File(self.file_name, "a", libver='earliest', 
                              driver='mpio', comm=MPI.COMM_WORLD)
                     else:
-                        f = hp.File(self.file_name, "w", libver='earliest')
+                        f = hp.File(self.file_name, "a", libver='earliest')
                     self._file_storage.append(f)
                 else:
                     raise ValueError("File is already open.")
@@ -669,7 +669,6 @@ class ProfileMonitor(Monitor):
                     self.write_count * self.buffer_size:(self.write_count+1) * 
                     self.buffer_size] = self.__getattribute__(dim + "_bin")
             
-        self.file.flush()
         self.write_count += 1
                     
     def track(self, object_to_save):