Author: Armin Rigo <[email protected]>
Branch: cpyext-gc-support
Changeset: r80172:26ca7b912f8c
Date: 2015-10-13 20:00 +0200
http://bitbucket.org/pypy/pypy/changeset/26ca7b912f8c/
Log: GC implementation
diff --git a/pypy/doc/discussion/rawrefcount.rst
b/pypy/doc/discussion/rawrefcount.rst
--- a/pypy/doc/discussion/rawrefcount.rst
+++ b/pypy/doc/discussion/rawrefcount.rst
@@ -39,7 +39,7 @@
Collection logic
----------------
-Objects exising purely on the C side have ob->ob_from_pypy == NULL;
+Objects existing purely on the C side have ob->ob_from_pypy == NULL;
these are purely reference counted. On the other hand, if
ob->ob_from_pypy != NULL, then ob->ob_refcnt is at least
REFCNT_FROM_PYPY_OBJECT and the object is part of a "link".
@@ -79,3 +79,20 @@
ob->ob_refcnt -= REFCNT_FROM_PYPY_OBJECT
if ob->ob_refcnt == 0:
invoke _Py_Dealloc(ob) later, outside the GC
+
+
+GC Implementation
+-----------------
+
+We need two P lists and two O lists, for young or old objects. All
+four lists can actually be linked lists of 'ob', using yet another
+field 'ob_pypy_next'; or they can be regular AddressLists (unsure
+about the overhead of this extra field for all PyObjects -- even ones
+not linked to PyPy objects).
+
+We also need an AddressDict mapping 'p' to 'ob' for all links in the P
+list. This dict contains both young and old 'p'; we simply write a
+new entry when the object moves. As a result it can contain some
+extra garbage entries after some minor collections. It is cleaned up
+by being rebuilt at the next major collection. We never walk all
+items of that dict; we only walk the two explicit P lists.
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