mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-03 08:34:29 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 6

Merged revisions 73694,73708,73738 via svnmerge from

Browse source 
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.
........
This commit is contained in:
Alexandre Vassalotti 2009-07-17 12:07:01 +00:00
parent 260484d12a
commit c57a84f41a
4 changed files with 108 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

36
Doc/library/multiprocessing.rst
View file

@ -1715,7 +1715,7 @@ authentication* using the :mod:`hmac` module.
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
@ -1757,7 +1757,7 @@ authentication* using the :mod:`hmac` module.
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`.
@ -2099,6 +2099,38 @@ Explicitly pass resources to child processes
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
~~~~~~~