Don't close drivers & sessions in finalizer (#1183)

No longer implicitly closing drivers and sessions in `__del__()`
(finalizer/destructor). Make sure to call `.close()` on them explicitly or use
them in a `with` statement.

A deprecation warning has been emitted in such cases before.

Relying on `__del__` leads to hard to follow control flow and can result in
surprising behavior as there is no guarantee when that the finalizer will be
called if ever. A ResourceWarning is emitted instead.

See also: https://docs.python.org/3/reference/datamodel.html#object.__del__

Author: robsdedude

CHANGELOG.md

@@ -91,6 +91,8 @@ See also https://github.com/neo4j/neo4j-python-driver/wiki for a full changelog.
 - Change behavior of closed drivers:
     - Raise `DriverError` on using the closed driver.
     - Calling `driver.close()` again is now a no-op.
+- No longer implicitly closing drivers and sessions in `__del__()` (finalizer/destructor).
+  Make sure to call `.close()` on them explicitly or use them in a `with` statement.
 
 
 ## Version 5.28

src/neo4j/_async/driver.py

@@ -39,7 +39,6 @@
     SECURITY_TYPE_SELF_SIGNED_CERTIFICATE,
     TelemetryAPI,
 )
-from .._async_compat.util import AsyncUtil
 from .._conf import (
     Config,
     ConfigurationError,
@@ -509,23 +508,9 @@ async def __aexit__(self, exc_type, exc_value, traceback):
     def __del__(
         self,
         _unclosed_resource_warn=unclosed_resource_warn,
-        _is_async_code=AsyncUtil.is_async_code,
-        _deprecation_warn=deprecation_warn,
     ):
         if not self._closed:
             _unclosed_resource_warn(self)
-        # TODO: 6.0 - remove this
-        if _is_async_code:
-            return
-        if not self._closed:
-            _deprecation_warn(
-                "Relying on AsyncDriver's destructor to close the session "
-                "is deprecated. Please make sure to close the session. "
-                "Use it as a context (`with` statement) or make sure to "
-                "call `.close()` explicitly. Future versions of the "
-                "driver will not close drivers automatically."
-            )
-            self.close()
 
     def _check_state(self):
         if self._closed:

src/neo4j/_async/work/workspace.py

@@ -22,15 +22,11 @@
 from ..._async_compat.util import AsyncUtil
 from ..._auth_management import to_auth_dict
 from ..._conf import WorkspaceConfig
-from ..._warnings import (
-    deprecation_warn,
-    unclosed_resource_warn,
-)
+from ..._warnings import unclosed_resource_warn
 from ...api import Bookmarks
 from ...exceptions import (
     ServiceUnavailable,
     SessionError,
-    SessionExpired,
 )
 from .._debug import AsyncNonConcurrentMethodChecker
 from ..io import (
@@ -74,29 +70,15 @@ def __init__(self, pool, config):
         self._closed = False
         super().__init__()
 
+    # Copy globals as function locals to make sure that they are available
+    # during Python shutdown when the Session is destroyed.
     def __del__(
         self,
         _unclosed_resource_warn=unclosed_resource_warn,
-        _is_async_code=AsyncUtil.is_async_code,
-        _deprecation_warn=deprecation_warn,
     ):
         if self._closed:
             return
         _unclosed_resource_warn(self)
-        # TODO: 6.0 - remove this
-        if _is_async_code:
-            return
-        try:
-            _deprecation_warn(
-                "Relying on AsyncSession's destructor to close the session "
-                "is deprecated. Please make sure to close the session. Use it "
-                "as a context (`with` statement) or make sure to call "
-                "`.close()` explicitly. Future versions of the driver will "
-                "not close sessions automatically."
-            )
-            self.close()
-        except (OSError, ServiceUnavailable, SessionExpired):
-            pass
 
     async def __aenter__(self) -> AsyncWorkspace:
         return self