fix: test failures

Author: adsharma

src_py/prepared_statement.py

@@ -33,6 +33,27 @@ def __init__(
         self._prepared_statement = connection._connection.prepare(query, parameters)
         self._connection = connection
 
+    def close(self) -> None:
+        """
+        Release the underlying C-API prepared statement resources.
+
+        The C-API ``PreparedStatement`` (from ``_lbug_capi.py``) holds a
+        ``lbug_prepared_statement`` C struct that must be destroyed explicitly;
+        it is NOT garbage-collected when the Python wrapper is dropped.
+        The pybind variant is managed by ``shared_ptr`` and can be dropped
+        without an explicit call.
+
+        ``Connection.close()`` iterates the implicit prepared-statement cache
+        and calls this method on every cached entry so that resources are
+        freed when the connection is closed.
+        """
+        close_fn = getattr(self._prepared_statement, "close", None)
+        if callable(close_fn):
+            close_fn()
+
+    def __del__(self) -> None:
+        self.close()
+
     def is_success(self) -> bool:
         """
         Check if the prepared statement is successfully prepared.

test/test_pybind_implicit_prepare_cache_threading.py

@@ -35,7 +35,10 @@
 )
 def test_shared_connection_concurrent_same_query(num_threads: int, iters: int) -> None:
     """Many threads on a single connection must each see its own bound value."""
-    db = lb.Database(":memory:", buffer_pool_size=2**28)
+    # Use an explicit max_db_size (1 GB) so the C-API backend does not default
+    # to the library's 8 TB mmap region, which fails on CI runners with tight
+    # virtual-address limits.
+    db = lb.Database(":memory:", buffer_pool_size=2**28, max_db_size=2**30)
     conn = lb.Connection(db)
 
     errors: list[tuple[int, list]] = []