Merged in prabhuramachandran/pysph/fix_parallel_adaptive_timestep (pu…

…ll request #146)


BUG: Fix parallel adaptive timesteps.

pysph/solver/solver.py

@@ -588,7 +588,15 @@ def _compute_timestep(self):
 
             # set the globally stable time step across all processors
             if self.in_parallel:
+                if dt is None:
+                    # For some reason this processor does not have an adaptive
+                    # timestep constraint so we set it to a large number so the
+                    # timestep is determined by the other processors.
+                    dt = 1e20
                 dt = self.pm.update_time_steps(dt)
+            else:
+                if dt is None:
+                    dt = undamped_dt
         else:
             dt = undamped_dt
 

pysph/sph/integrator.py

@@ -66,6 +66,9 @@ def compute_h_minimum(self):
         self.h_minimum = hmin
 
     def compute_time_step(self, dt, cfl):
+        """If there are any adaptive timestep constraints, the appropriate
+        timestep is returned, else None is returned.
+        """
         a_eval = self.c_integrator.acceleration_eval
 
         # different time step controls
@@ -102,7 +105,7 @@ def compute_time_step(self, dt, cfl):
         # return the computed time steps. If dt factors aren't
         # defined, the default dt is returned
         if dt_min <= 0.0:
-            return dt
+            return None
         else:
             return cfl*dt_min