fix(sql): don't classify objects with permissive __getattr__ as connections

marimo/_sql/engines/adbc.py

@@ -17,6 +17,7 @@
     InferenceConfig,
     SQLConnection,
     default_inference_config,
+    fabricates_attributes,
 )
 from marimo._sql.utils import convert_to_output, is_cheap_dialect
 from marimo._types.ids import VariableName
@@ -461,6 +462,11 @@ def is_compatible(var: Any) -> bool:
         if var_type_name == "ibis.common.deferred.Deferred":
             return False
 
+        # Objects with a permissive __getattr__ (e.g. pytorch-ignite metrics)
+        # pass any getattr-based check and hang catalog introspection. #10213
+        if fabricates_attributes(var):
+            return False
+
         try:
             # First, validate the connection-level surface area to avoid
             # accidentally classifying regular DB-API connections as ADBC.

marimo/_sql/engines/dbapi.py

@@ -5,7 +5,7 @@
 from typing import TYPE_CHECKING, Any, Protocol
 
 from marimo import _loggers
-from marimo._sql.engines.types import QueryEngine
+from marimo._sql.engines.types import QueryEngine, fabricates_attributes
 from marimo._sql.utils import convert_to_output
 
 LOGGER = _loggers.marimo_logger()
@@ -112,6 +112,11 @@ def is_compatible(var: Any) -> bool:
         if var_type_name == "ibis.common.deferred.Deferred":
             return False
 
+        # Objects with a permissive __getattr__ (e.g. pytorch-ignite metrics)
+        # pass any getattr-based check and hang catalog introspection. #10213
+        if fabricates_attributes(var):
+            return False
+
         try:
             required_methods = ["cursor", "commit", "rollback", "close"]
             has_required_methods = all(

marimo/_sql/engines/types.py

@@ -23,6 +23,28 @@
 
 NO_SCHEMA_NAME = ""
 
+# Attribute that no real database connection defines; used to detect objects
+# that fabricate attributes via a permissive __getattr__.
+_MISSING_ATTRIBUTE_PROBE = "_marimo_does_not_exist_"
+
+
+def fabricates_attributes(var: Any) -> bool:
+    """Whether `var` fabricates attributes via a permissive `__getattr__`.
+
+    Some objects return a new object for *any* attribute name (for example
+    pytorch-ignite metrics, which build lazy `MetricsLambda` graphs). Such
+    objects pass every `getattr`-based duck-typing check, and catalog
+    introspection on them can hang. Genuine connection proxies that forward
+    `__getattr__` to an underlying connection are unaffected, since the
+    probe attribute does not exist there either.
+    """
+    try:
+        return getattr(var, _MISSING_ATTRIBUTE_PROBE, None) is not None
+    except Exception:
+        # A __getattr__ that raises something other than AttributeError is
+        # not a usable connection either.
+        return True
+
 
 @dataclass
 class InferenceConfig(ABC):

tests/_sql/test_adbc.py

@@ -425,6 +425,20 @@ def test_adbc_execute_native_returns_arrow_table(monkeypatch) -> None:
     assert cursor.did_close is True
 
 
+def test_adbc_is_compatible_rejects_fabricated_attributes() -> None:
+    # Objects with a permissive __getattr__ (e.g. pytorch-ignite metrics)
+    # resolve any attribute name, so they pass getattr-based duck typing
+    # and catalog introspection on them hangs. See #10213.
+    class FabricatingAttributes:
+        def __getattr__(self, name: str) -> object:
+            def _lazy(*_args: object, **_kwargs: object) -> object:
+                return FabricatingAttributes()
+
+            return _lazy
+
+    assert AdbcDBAPIEngine.is_compatible(FabricatingAttributes()) is False
+
+
 def test_adbc_is_compatible_does_not_create_cursor() -> None:
     conn = FakeAdbcDbApiConnection(
         cursor=FakeAdbcDbApiCursor(description=None),

tests/_sql/test_dbapi.py

@@ -58,6 +58,20 @@ def test_is_compatible() -> None:
     assert not isinstance(engine, EngineCatalog)
 
 
+def test_is_compatible_rejects_fabricated_attributes() -> None:
+    # Objects with a permissive __getattr__ (e.g. pytorch-ignite metrics)
+    # resolve any attribute name, so they pass getattr-based duck typing
+    # and catalog introspection on them hangs. See #10213.
+    class FabricatingAttributes:
+        def __getattr__(self, name: str) -> object:
+            def _lazy(*_args: object, **_kwargs: object) -> object:
+                return FabricatingAttributes()
+
+            return _lazy
+
+    assert not DBAPIEngine.is_compatible(FabricatingAttributes())
+
+
 def test_execute_native(dbapi_engine: DBAPIEngine) -> None:
     with patch.object(
         dbapi_engine, "sql_output_format", return_value="native"

tests/_sql/test_get_engines.py

@@ -482,3 +482,19 @@ def test_variables_without_datasource_engine() -> None:
     variables = [("deferred_for_test", deferred_for_test)]
     engines = get_engines_from_variables(variables)
     assert not engines
+
+
+def test_fabricated_attributes_not_treated_as_engine() -> None:
+    # Objects with a permissive __getattr__ (e.g. pytorch-ignite metrics)
+    # resolve any attribute name, so they pass getattr-based duck typing
+    # and catalog introspection on them hangs. See #10213.
+    class FabricatingAttributes:
+        def __getattr__(self, name: str) -> object:
+            def _lazy(*_args: object, **_kwargs: object) -> object:
+                return FabricatingAttributes()
+
+            return _lazy
+
+    variables = [(VariableName("metric"), FabricatingAttributes())]
+    engines = get_engines_from_variables(variables)
+    assert not engines