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author | ko1 <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2013-06-18 19:50:44 +0000 |
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committer | ko1 <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2013-06-18 19:50:44 +0000 |
commit | 67d6aaca3521f6fe089103e72157e05ee950882a (patch) | |
tree | 1b75a0e459d8935fc282d35f7c88edb79b94ff18 /ChangeLog | |
parent | 81568a297b21334014c51fbde6c0026f1c6c86c3 (diff) | |
download | ruby-67d6aaca3521f6fe089103e72157e05ee950882a.tar.gz |
* variable.c (rb_const_set): fix WB miss.
WBs had located before creating reference between a klass
and constant value. It causes GC bug.
# pseudo code:
WB(klass, value); # WB and remember klass
st_insert(klass->const_table, const_id, value);
`st_insert()' can cause GC before inserting `value' and
forget `klass' from the remember set. After that, relationship
between `klass' and `value' are created with constant table.
Now, `value' can be young (shady) object and `klass' can be old
object, without remembering `klass' object.
At the next GC, old `klass' object will be skipped and
young (shady) `value' will be miss-collected. -> GC bug
Lesson: The place of a WB is important.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41396 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'ChangeLog')
-rw-r--r-- | ChangeLog | 21 |
1 files changed, 21 insertions, 0 deletions
@@ -1,3 +1,24 @@ +Wed Jun 19 04:33:22 2013 Koichi Sasada <ko1@atdot.net> + + * variable.c (rb_const_set): fix WB miss. + + WBs had located before creating reference between a klass + and constant value. It causes GC bug. + + # pseudo code: + WB(klass, value); # WB and remember klass + st_insert(klass->const_table, const_id, value); + + `st_insert()' can cause GC before inserting `value' and + forget `klass' from the remember set. After that, relationship + between `klass' and `value' are created with constant table. + Now, `value' can be young (shady) object and `klass' can be old + object, without remembering `klass' object. + At the next GC, old `klass' object will be skipped and + young (shady) `value' will be miss-collected. -> GC bug + + Lesson: The place of a WB is important. + Tue Jun 18 22:01:00 2013 Charlie Somerville <charliesome@ruby-lang.org> * vm_insnhelper.c (vm_call_method): ensure methods of type |