[Python-checkins] cpython (3.2): Issue #15881: Fixed atexit hook in multiprocessing.

Sun Sep 9 19:28:07 CEST 2012

http://hg.python.org/cpython/rev/27d410dd5431
changeset: 78922:27d410dd5431
branch: 3.2
parent: 78895:adc5e6aca251
user: Alexander Belopolsky <alexander.belopolsky at gmail.com>
date: Sun Sep 09 13:16:15 2012 -0400
summary:
 Issue #15881: Fixed atexit hook in multiprocessing.
files:
 Doc/ACKS.txt | 1 +
 Lib/multiprocessing/util.py | 50 ++++++++++++++++++-------
 2 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/Doc/ACKS.txt b/Doc/ACKS.txt
--- a/Doc/ACKS.txt
+++ b/Doc/ACKS.txt
@@ -236,3 +236,4 @@
 * Moshe Zadka
 * Milan Zamazal
 * Cheng Zhang
+ * Chris McDonough
diff --git a/Lib/multiprocessing/util.py b/Lib/multiprocessing/util.py
--- a/Lib/multiprocessing/util.py
+++ b/Lib/multiprocessing/util.py
@@ -247,6 +247,12 @@
 Finalizers with highest priority are called first; finalizers with
 the same priority will be called in reverse order of creation.
 '''
+ if _finalizer_registry is None:
+ # This function may be called after this module's globals are
+ # destroyed. See the _exit_function function in this module for more
+ # notes.
+ return
+ 
 if minpriority is None:
 f = lambda p : p[0][0] is not None
 else:
@@ -278,24 +284,40 @@
 
 _exiting = False
 
-def _exit_function():
+def _exit_function(info=info, debug=debug, _run_finalizers=_run_finalizers,
+ active_children=active_children,
+ current_process=current_process):
+ # We hold on to references to functions in the arglist due to the
+ # situation described below, where this function is called after this
+ # module's globals are destroyed.
+
 global _exiting
 
- info('process shutting down')
- debug('running all "atexit" finalizers with priority >= 0')
- _run_finalizers(0)
+ if not _exiting:
+ info('process shutting down')
+ debug('running all "atexit" finalizers with priority >= 0')
+ _run_finalizers(0)
+ if current_process() is not None:
+ # We check if the current process is None here because if
+ # it's None, any call to ``active_children()`` will throw an
+ # AttributeError (active_children winds up trying to get
+ # attributes from util._current_process). This happens in a
+ # variety of shutdown circumstances that are not well-understood
+ # because module-scope variables are not apparently supposed to
+ # be destroyed until after this function is called. However,
+ # they are indeed destroyed before this function is called. See
+ # issues #9775 and #15881. Also related: #4106, #9205, and #9207.
+ for p in active_children():
+ if p._daemonic:
+ info('calling terminate() for daemon %s', p.name)
+ p._popen.terminate()
 
- for p in active_children():
- if p._daemonic:
- info('calling terminate() for daemon %s', p.name)
- p._popen.terminate()
+ for p in active_children():
+ info('calling join() for process %s', p.name)
+ p.join()
 
- for p in active_children():
- info('calling join() for process %s', p.name)
- p.join()
-
- debug('running the remaining "atexit" finalizers')
- _run_finalizers()
+ debug('running the remaining "atexit" finalizers')
+ _run_finalizers()
 
 atexit.register(_exit_function)
 
-- 
Repository URL: http://hg.python.org/cpython
