added monkeypatch to resolve known dask bug

minerva/cluster.py

@@ -113,3 +113,22 @@ class Cluster:
         return security_group_id
 
 
+# Monkeypatch to address a known bug in Dask
+# https://github.com/dask/distributed/issues/4305
+from dask.distributed import Future
+import sys
+
+def monkeypatch_del(self):
+    try:
+        self.release()
+    except AttributeError:
+        # Occasionally we see this error when shutting down the client
+        # https://github.com/dask/distributed/issues/4305
+        if not sys.is_finalizing():
+            raise
+        #pass
+    except RuntimeError:  # closed event loop
+        pass
+
+Future.__del__ = monkeypatch_del
+