From 99c160b559dc6c510e2e9f713191c3c80e26c6f2 Mon Sep 17 00:00:00 2001 From: Antoine Pitrou Date: Thu, 5 Nov 2009 13:42:29 +0000 Subject: Issue #7264: Fix a possible deadlock when deallocating thread-local objects which are part of a reference cycle. --- Lib/_threading_local.py | 8 +++++--- Lib/threading.py | 4 ++++ Misc/NEWS | 3 +++ 3 files changed, 12 insertions(+), 3 deletions(-) diff --git a/Lib/_threading_local.py b/Lib/_threading_local.py index 4eda630..243d84e 100644 --- a/Lib/_threading_local.py +++ b/Lib/_threading_local.py @@ -218,10 +218,12 @@ class local(_localbase): key = object.__getattribute__(self, '_local__key') try: - threads = list(threading.enumerate()) + # We use the non-locking API since we might already hold the lock + # (__del__ can be called at any point by the cyclic GC). + threads = threading._enumerate() except: - # If enumerate fails, as it seems to do during - # shutdown, we'll skip cleanup under the assumption + # If enumerating the current threads fails, as it seems to do + # during shutdown, we'll skip cleanup under the assumption # that there is nothing to clean up. return diff --git a/Lib/threading.py b/Lib/threading.py index cf20152..9ad5122 100644 --- a/Lib/threading.py +++ b/Lib/threading.py @@ -810,6 +810,10 @@ def activeCount(): active_count = activeCount +def _enumerate(): + # Same as enumerate(), but without the lock. Internal use only. + return _active.values() + _limbo.values() + def enumerate(): with _active_limbo_lock: return _active.values() + _limbo.values() diff --git a/Misc/NEWS b/Misc/NEWS index 183aa7a..8ae9afb 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -426,6 +426,9 @@ Core and Builtins Library ------- +- Issue #7264: Fix a possible deadlock when deallocating thread-local objects + which are part of a reference cycle. + - Issue #7211: Allow 64-bit values for the `ident` and `data` fields of kevent objects on 64-bit systems. Patch by Michael Broghton. -- cgit v0.12