Hi all, I've been trying to run rockstar in a sizable Enzo simulation (150k grids) with ~100 outputs, where it's running out of memory just loading the hierarchies. One hierarchy instance consumes almost 1GB! I've found this to be problem not specific to rockstar but time series objects. My solution is to explicitly delete the hierarchy's metadata and grids. Since I haven't contributed to yt-3.0 yet, I wanted to run this by everyone before submitting a PR. My question is about coding style, in that I see very few __del__() functions now. In my working version, I've defined a __del__ function for the grid_geometry_handler as def __del__(self): del self.grid_dimensions del self.grid_left_edge del self.grid_right_edge del self.grid_levels del self.grid_particle_count del self.grids When I delete pf._instantiated_hierarchy after each loop of a time series iterator, I don't see any excessive memory usage anymore. It just reuses the allocated memory from the previous iteration, which is totally fine by me. However, when I include this in a __del__ function for a static_output, I still see excessive memory usage, which is bizarre to me. Should I define a new routine in the grid_geometry_handler, something like clear_hierarchy(), or keep the __del__ function? I ask because I want to keep in line with the overall structure of yt-3.0. This could also be included in the clear_all_data() call. What do people think the best approach would be? Thanks, John -- John Wise Assistant Professor of Physics Center for Relativistic Astrophysics, Georgia Tech http://cosmo.gatech.edu