Ephemeron objects are treated specially in that the objects that are
only reachable from them are marked later in the GC. This however does
not apply to the class object. For this reason: 1) all ephemerons are
added to a buffer for later processing; 2) tail recursion is used to
mark the class object.
However, the case of tail recursion is very rare because it happens only
if the ephemeron class has not already been marked before -- and all
classes usually are marked very early when the Smalltalk dictionary is
marked. It is so rare that it was buggy. :-) In the latest master, the
bug was triggered by loading the ANSI testsuite. Luckily, it's trivial
to fix and the only struggling was to find that the bug was caused by an
ephemeron not in the buffer.
Committed to master and stable-3.0.
Paolo
diff --git a/libgst/ChangeLog b/libgst/ChangeLog
index 7bfab36..ff87720 100644
--- a/libgst/ChangeLog
+++ b/libgst/ChangeLog
@@ -1,3 +1,9 @@
+2008-05-14 Paolo Bonzini <
[hidden email]>
+
+ * libgst/oop.c: Add ephemerons to buffer before marking their class
+ (else, if the class actually has to be marked, we won't add them to the
+ buffer at all).
+
2008-05-13 Paolo Bonzini <
[hidden email]>
* libgst/callin.h: Add _gst_oop_indexed_base and _gst_oop_indexed_kind.
diff --git a/libgst/oop.c b/libgst/oop.c
index 3eb1fb7..96c57cf 100644
--- a/libgst/oop.c
+++ b/libgst/oop.c
@@ -2197,14 +2197,14 @@ _gst_mark_an_oop_internal (OOP oop,
}
else if UNCOMMON (oop->flags & (F_EPHEMERON | F_WEAK))
{
+ if (oop->flags & F_EPHEMERON)
+ _gst_add_buf_pointer (oop);
+
/* In general, there will be many instances of a class,
but only the first time will it be unmarked. So I'm
marking this as uncommon. */
if UNCOMMON (!IS_OOP_MARKED (objClass))
TAIL_MARK_OOP (objClass);
-
- if (oop->flags & F_EPHEMERON)
- _gst_add_buf_pointer (oop);
}
else
{
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