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| author | Tim Peters <tim.peters@gmail.com> | 2003-11-20 21:21:46 +0000 |
|---|---|---|
| committer | Tim Peters <tim.peters@gmail.com> | 2003-11-20 21:21:46 +0000 |
| commit | 9204576b93fd3a0a5b658d43a0756ef71a514d10 (patch) | |
| tree | d6fc6a6804a7641dd5551b8734ace4a69de88191 /Misc | |
| parent | f8a46271005dbec94d1bd023baecfb4b7d60f7a6 (diff) | |
| download | cpython-9204576b93fd3a0a5b658d43a0756ef71a514d10.tar.gz | |
SF bug 839548: Bug in type's GC handling causes segfaults.
Also SF patch 843455.
This is a critical bugfix.
I'll backport to 2.3 maint, but not beyond that. The bugs this fixes
have been there since weakrefs were introduced.
Diffstat (limited to 'Misc')
| -rw-r--r-- | Misc/NEWS | 21 |
1 files changed, 18 insertions, 3 deletions
@@ -12,9 +12,20 @@ What's New in Python 2.4 alpha 1? Core and builtins ----------------- -- Compiler flags set in PYTHONSTARTUP are now active in __main__. - -- Added two builtin types, set() and frozenset(). +- Critical bugfix, for SF bug 839548: if a weakref with a callback, + its callback, and its weakly referenced object, all became part of + cyclic garbage during a single run of garbage collection, the order + in which they were torn down was unpredictable. It was possible for + the callback to see partially-torn-down objects, leading to immediate + segfaults, or, if the callback resurrected garbage objects, to + resurrect insane objects that caused segfaults (or other surprises) + later. In one sense this wasn't surprising, because Python's cyclic gc + had no knowledge of Python's weakref objects. It does now. When + weakrefs with callbacks become part of cyclic garbage now, those + weakrefs are cleared first. The callbacks don't trigger then, + preventing the problems. If you need callbacks to trigger, then just + as when cyclic gc is not involved, you need to write your code so + that weakref objects outlive the objects they weakly reference. - Critical bugfix, for SF bug 840829: if cyclic garbage collection happened to occur during a weakref callback for a new-style class @@ -22,6 +33,10 @@ Core and builtins in a debug build, a segfault occurred reliably very soon after). This has been repaired. +- Compiler flags set in PYTHONSTARTUP are now active in __main__. + +- Added two builtin types, set() and frozenset(). + - Added a reversed() builtin function that returns a reverse iterator over a sequence. |