sqlite3 Connection maintains an unused list of weakrefs to Cursor objects

[takluyver]

The sqlite3 Connection object creates a list to hold weakrefs to Cursors, and each cursor registers itself in that list when it's created.

cpython/Modules/_sqlite/connection.c

Lines 289 to 293 in b625601

	PyObject *cursors = PyList_New(0);
	if (cursors == NULL) {
	Py_DECREF(statement_cache);
	goto error;
	}

cpython/Modules/_sqlite/cursor.c

Lines 108 to 122 in b625601

	register_cursor(pysqlite_Connection *connection, PyObject *cursor)
	{
	PyObject *weakref = PyWeakref_NewRef((PyObject *)cursor, NULL);
	if (weakref == NULL) {
	return 0;
	}
	if (PyList_Append(connection->cursors, weakref) < 0) {
	Py_CLEAR(weakref);
	return 0;
	}
	Py_DECREF(weakref);
	return 1;
	}

There's code to periodically clear out dead weakrefs from the list, but nothing I can see that actually uses it. It looks like the use was removed in #26026.

Linked PRs

• gh-144377: Clean up sqlite3 Connection's list of weakrefs to Cursor objects #144378

[erlend-aasland]

Thanks, @takluyver; happy to see this code go!