Add explicit grid destroy when deleting Regridder (#387)

Co-authored-by: raphael dussin <[email protected]>

CHANGES.rst

@@ -1,6 +1,10 @@
 What's new
 ==========
 
+0.8.8 (unreleased)
+------------------
+* Fix ESMpy memory issues by explictly freeing the Grid memory upon garbage collection of ``Regridder`` objects. By `Pascal Bourgault <https://github.com/aulemahal>`_.
+
 0.8.7 (2024-07-16)
 ------------------
 * Cast grid sizes to python's int (another Numpy 2.0 fix). (:pull:`377`) By `Pascal Bourgault <https://github.com/aulemahal>`_.

xesmf/frontend.py

@@ -1109,6 +1109,12 @@ def _format_xroutput(self, out, new_dims=None):
 
         return out
 
+    def __del__(self):
+        # Memory leak issue when regridding over a large number of datasets with xESMF
+        # https://github.com/JiaweiZhuang/xESMF/issues/53
+        self.grid_in.destroy()
+        self.grid_out.destroy()
+
 
 class SpatialAverager(BaseRegridder):
     def __init__(
@@ -1372,3 +1378,9 @@ def _format_xroutput(self, out, new_dims=None):
         out.coords[self._lat_out_name] = xr.DataArray(self._lat_out, dims=(self.geom_dim_name,))
         out.attrs['regrid_method'] = self.method
         return out
+
+    def __del__(self):
+        # Memory leak issue when regridding over a large number of datasets with xESMF
+        # https://github.com/JiaweiZhuang/xESMF/issues/53
+        self.grid_in.destroy()
+        self.grid_out.destroy()