[Python-checkins] r74251 - in python/branches/release31-maint: Doc/library/multiprocessing.rst Lib/multiprocessing/process.py Lib/test/test_multiprocessing.py Misc/ACKS Misc/NEWS
r.david.murray
python-checkins at python.org
Wed Jul 29 17:40:31 CEST 2009
Author: r.david.murray
Date: Wed Jul 29 17:40:30 2009
New Revision: 74251
Log:
Merged revisions 74063 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k
NB: the news item for r73708 seems to have inadvertently been included in a
different, unrelated merge set (r74055). I restored it here.
................
r74063 | alexandre.vassalotti | 2009-07-17 08:07:01 -0400 (Fri, 17 Jul 2009) | 17 lines
Merged revisions 73694,73708,73738 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r73694 | jesse.noller | 2009-06-29 14:24:26 -0400 (Mon, 29 Jun 2009) | 1 line
Issue 5740: multiprocessing.connection.* authkey fixes
........
r73708 | jesse.noller | 2009-06-30 13:11:52 -0400 (Tue, 30 Jun 2009) | 1 line
Resolves issues 5155, 5313, 5331 - bad file descriptor error with processes in processes
........
r73738 | r.david.murray | 2009-06-30 22:49:10 -0400 (Tue, 30 Jun 2009) | 2 lines
Make punctuation prettier and break up run-on sentence.
........
................
Modified:
python/branches/release31-maint/ (props changed)
python/branches/release31-maint/Doc/library/multiprocessing.rst
python/branches/release31-maint/Lib/multiprocessing/process.py
python/branches/release31-maint/Lib/test/test_multiprocessing.py
python/branches/release31-maint/Misc/ACKS
python/branches/release31-maint/Misc/NEWS
Modified: python/branches/release31-maint/Doc/library/multiprocessing.rst
==============================================================================
--- python/branches/release31-maint/Doc/library/multiprocessing.rst (original)
+++ python/branches/release31-maint/Doc/library/multiprocessing.rst Wed Jul 29 17:40:30 2009
@@ -1713,7 +1713,7 @@
generally be omitted since it can usually be inferred from the format of
*address*. (See :ref:`multiprocessing-address-formats`)
- If *authentication* is ``True`` or *authkey* is a string then digest
+ If *authenticate* is ``True`` or *authkey* is a string then digest
authentication is used. The key used for authentication will be either
*authkey* or ``current_process().authkey)`` if *authkey* is ``None``.
If authentication fails then :exc:`AuthenticationError` is raised. See
@@ -1755,7 +1755,7 @@
If *authkey* is ``None`` and *authenticate* is ``True`` then
``current_process().authkey`` is used as the authentication key. If
- *authkey* is ``None`` and *authentication* is ``False`` then no
+ *authkey* is ``None`` and *authenticate* is ``False`` then no
authentication is done. If authentication fails then
:exc:`AuthenticationError` is raised. See :ref:`multiprocessing-auth-keys`.
@@ -2097,6 +2097,38 @@
for i in range(10):
Process(target=f, args=(lock,)).start()
+Beware replacing sys.stdin with a "file like object"
+
+ :mod:`multiprocessing` originally unconditionally called::
+
+ os.close(sys.stdin.fileno())
+
+ in the :meth:`multiprocessing.Process._bootstrap` method --- this resulted
+ in issues with processes-in-processes. This has been changed to::
+
+ sys.stdin.close()
+ sys.stdin = open(os.devnull)
+
+ Which solves the fundamental issue of processes colliding with each other
+ resulting in a bad file descriptor error, but introduces a potential danger
+ to applications which replace :func:`sys.stdin` with a "file-like object"
+ with output buffering. This danger is that if multiple processes call
+ :func:`close()` on this file-like object, it could result in the same
+ data being flushed to the object multiple times, resulting in corruption.
+
+ If you write a file-like object and implement your own caching, you can
+ make it fork-safe by storing the pid whenever you append to the cache,
+ and discarding the cache when the pid changes. For example::
+
+ @property
+ def cache(self):
+ pid = os.getpid()
+ if pid != self._pid:
+ self._pid = pid
+ self._cache = []
+ return self._cache
+
+ For more information, see :issue:`5155`, :issue:`5313` and :issue:`5331`
Windows
~~~~~~~
Modified: python/branches/release31-maint/Lib/multiprocessing/process.py
==============================================================================
--- python/branches/release31-maint/Lib/multiprocessing/process.py (original)
+++ python/branches/release31-maint/Lib/multiprocessing/process.py Wed Jul 29 17:40:30 2009
@@ -221,7 +221,8 @@
self._counter = itertools.count(1)
if sys.stdin is not None:
try:
- os.close(sys.stdin.fileno())
+ sys.stdin.close()
+ sys.stdin = open(os.devnull)
except (OSError, ValueError):
pass
_current_process = self
Modified: python/branches/release31-maint/Lib/test/test_multiprocessing.py
==============================================================================
--- python/branches/release31-maint/Lib/test/test_multiprocessing.py (original)
+++ python/branches/release31-maint/Lib/test/test_multiprocessing.py Wed Jul 29 17:40:30 2009
@@ -8,6 +8,7 @@
import threading
import queue as pyqueue
import time
+import io
import sys
import os
import gc
@@ -1862,7 +1863,74 @@
p.join()
self.assertEqual(self.ns.test, 1)
-testcases_other = [OtherTest, TestInvalidHandle, TestInitializers]
+#
+# Issue 5155, 5313, 5331: Test process in processes
+# Verifies os.close(sys.stdin.fileno) vs. sys.stdin.close() behavior
+#
+
+def _ThisSubProcess(q):
+ try:
+ item = q.get(block=False)
+ except pyqueue.Empty:
+ pass
+
+def _TestProcess(q):
+ queue = multiprocessing.Queue()
+ subProc = multiprocessing.Process(target=_ThisSubProcess, args=(queue,))
+ subProc.start()
+ subProc.join()
+
+def _afunc(x):
+ return x*x
+
+def pool_in_process():
+ pool = multiprocessing.Pool(processes=4)
+ x = pool.map(_afunc, [1, 2, 3, 4, 5, 6, 7])
+
+class _file_like(object):
+ def __init__(self, delegate):
+ self._delegate = delegate
+ self._pid = None
+
+ @property
+ def cache(self):
+ pid = os.getpid()
+ # There are no race conditions since fork keeps only the running thread
+ if pid != self._pid:
+ self._pid = pid
+ self._cache = []
+ return self._cache
+
+ def write(self, data):
+ self.cache.append(data)
+
+ def flush(self):
+ self._delegate.write(''.join(self.cache))
+ self._cache = []
+
+class TestStdinBadfiledescriptor(unittest.TestCase):
+
+ def test_queue_in_process(self):
+ queue = multiprocessing.Queue()
+ proc = multiprocessing.Process(target=_TestProcess, args=(queue,))
+ proc.start()
+ proc.join()
+
+ def test_pool_in_process(self):
+ p = multiprocessing.Process(target=pool_in_process)
+ p.start()
+ p.join()
+
+ def test_flushing(self):
+ sio = io.StringIO()
+ flike = _file_like(sio)
+ flike.write('foo')
+ proc = multiprocessing.Process(target=lambda: flike.flush())
+ flike.flush()
+ assert sio.getvalue() == 'foo'
+
+testcases_other = [OtherTest, TestInvalidHandle, TestInitializers,
+ TestStdinBadfiledescriptor]
#
#
Modified: python/branches/release31-maint/Misc/ACKS
==============================================================================
--- python/branches/release31-maint/Misc/ACKS (original)
+++ python/branches/release31-maint/Misc/ACKS Wed Jul 29 17:40:30 2009
@@ -45,6 +45,7 @@
Ulf Bartelt
Nick Bastin
Jeff Bauer
+Mike Bayer
Michael R Bax
Anthony Baxter
Samuel L. Bayer
@@ -184,6 +185,7 @@
Dean Draayer
John DuBois
Paul Dubois
+Graham Dumpleton
Quinn Dunkan
Robin Dunn
Luke Dunstan
@@ -556,6 +558,7 @@
Santiago Peresón
Mark Perrego
Trevor Perrin
+Gabriel de Perthuis
Tim Peters
Benjamin Peterson
Chris Petrilli
Modified: python/branches/release31-maint/Misc/NEWS
==============================================================================
--- python/branches/release31-maint/Misc/NEWS (original)
+++ python/branches/release31-maint/Misc/NEWS Wed Jul 29 17:40:30 2009
@@ -42,6 +42,10 @@
Library
-------
+- Issues #5155, #5313, #5331: multiprocessing.Process._bootstrap was
+ unconditionally calling "os.close(sys.stdin.fileno())" resulting in file
+ descriptor errors
+
- Issue #1424152: Fix for http.client, urllib.request to support SSL while
working through proxy. Original patch by Christopher Li, changes made by
Senthil Kumaran
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