Expand comments.
Explicitly clear all elements from arena->a_objects and remove
assert() that refcount is 1. It's possible for a program to get a
reference to the list via sys.getobjects() or via gc functions.
diff --git a/Python/pyarena.c b/Python/pyarena.c
index 242ca1d..012c46b 100644
--- a/Python/pyarena.c
+++ b/Python/pyarena.c
@@ -6,6 +6,9 @@
Measurements with standard library modules suggest the average
allocation is about 20 bytes and that most compiles use a single
block.
+
+ TODO(jhylton): Think about a realloc API, maybe just for the last
+ allocation?
*/
#define DEFAULT_BLOCK_SIZE 8192
@@ -39,9 +42,25 @@
*/
struct _arena {
+ /* Pointer to the first block allocated for the arena, never NULL.
+ It is used only to find the first block when the arena is
+ being freed.
+ */
block *a_head;
+
+ /* Pointer to the block currently used for allocation. It's
+ ab_next field should be NULL. If it is not-null after a
+ call to block_alloc(), it means a new block has been allocated
+ and a_cur should be reset to point it.
+ */
block *a_cur;
+
+ /* A Python list object containing references to all the PyObject
+ pointers associated with this area. They will be DECREFed
+ when the arena is freed.
+ */
PyObject *a_objects;
+
#if defined(Py_DEBUG)
/* Debug output */
size_t total_allocs;
@@ -134,6 +153,7 @@
void
PyArena_Free(PyArena *arena)
{
+ int r;
assert(arena);
#if defined(Py_DEBUG)
/*
@@ -146,6 +166,13 @@
#endif
block_free(arena->a_head);
assert(arena->a_objects->ob_refcnt == 1);
+
+ /* Clear all the elements from the list. This is necessary
+ to guarantee that they will be DECREFed. */
+ r = PyList_SetSlice(arena->a_objects,
+ 0, PyList_GET_SIZE(arena->a_objects), NULL);
+ assert(r == 0);
+ assert(PyList_GET_SIZE(arena->a_objects) == 0);
Py_DECREF(arena->a_objects);
free(arena);
}