Handle __del__ more gracefully

exasol/driver/websocket/_connection.py

@@ -150,4 +150,16 @@ def cursor(self):
         return DefaultCursor(self)
 
     def __del__(self):
-        self.close()
+        if self._connection is None:
+            return
+
+        # Currently, the only way to handle this gracefully is to invoke the`__del__`
+        # method of the underlying connection rather than calling an explicit `close`.
+        #
+        # For more details, see also:
+        # * https://github.com/exasol/sqlalchemy-exasol/issues/390
+        # * https://github.com/exasol/pyexasol/issues/108
+        #
+        # If the above tickets are resolved, it should be safe to switch back to using
+        # `close` instead of `__del__`.
+        self._connection.__del__()

test/integration/regression/test_regression_bug390.py

@@ -3,14 +3,14 @@
 pytest_plugins = "pytester"
 
 
-def test_connection_with_block_cleans_up_properly(pytester, itde):
-    config = itde.db
+def test_connection_with_block_cleans_up_properly(pytester, exasol_config):
+    config = exasol_config
     # Because the error only occurs on process shutdown we need to run a test within a test
     # (We require the result (stderr) of a terminated process triggering the failure.
     pytester.makepyfile(
         # fmt: off
         cleandoc(
-        f"""
+            f"""
         from sqlalchemy import create_engine
         
         def test():
@@ -20,7 +20,7 @@ def test():
                 pw="{config.password}",
                 host="{config.host}",
                 port={config.port},
-                schema="{itde.itde.schemas[0]}",
+                schema="TEST",
             )
             engine = create_engine(url)
             query = "SELECT 42;"