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Fixes issue #17488: Change the subprocess.Popen bufsize parameter default value

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from unbuffered (0) to buffering (-1) to match the behavior existing code
expects and match the behavior of the subprocess module in Python 2 to avoid
introducing hard to track down bugs.
This commit is contained in:
Gregory P. Smith 2013-03-23 12:00:00 -07:00
commit 4a8ea9e2a6
4 changed files with 55 additions and 19 deletions
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18
Lib/subprocess.py
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@ -25,7 +25,7 @@ Using the subprocess module
===========================
This module defines one class called Popen:
class Popen(args, bufsize=0, executable=None,
class Popen(args, bufsize=-1, executable=None,
stdin=None, stdout=None, stderr=None,
preexec_fn=None, close_fds=True, shell=False,
cwd=None, env=None, universal_newlines=False,
@ -56,12 +56,12 @@ not all MS Windows applications interpret the command line the same
way: The list2cmdline is designed for applications using the same
rules as the MS C runtime.
bufsize, if given, has the same meaning as the corresponding argument
to the built-in open() function: 0 means unbuffered, 1 means line
buffered, any other positive value means use a buffer of
(approximately) that size. A negative bufsize means to use the system
default, which usually means fully buffered. The default value for
bufsize is 0 (unbuffered).
bufsize will be supplied as the corresponding argument to the io.open()
function when creating the stdin/stdout/stderr pipe file objects:
0 means unbuffered (read & write are one system call and can return short),
1 means line buffered, any other positive value means use a buffer of
approximately that size. A negative bufsize, the default, means the system
default of io.DEFAULT_BUFFER_SIZE will be used.
stdin, stdout and stderr specify the executed programs' standard
input, standard output and standard error file handles, respectively.
@ -709,7 +709,7 @@ _PLATFORM_DEFAULT_CLOSE_FDS = object()
class Popen(object):
def __init__(self, args, bufsize=0, executable=None,
def __init__(self, args, bufsize=-1, executable=None,
stdin=None, stdout=None, stderr=None,
preexec_fn=None, close_fds=_PLATFORM_DEFAULT_CLOSE_FDS,
shell=False, cwd=None, env=None, universal_newlines=False,
@ -723,7 +723,7 @@ class Popen(object):
self._input = None
self._communication_started = False
if bufsize is None:
bufsize = 0 # Restore default
bufsize = -1 # Restore default
if not isinstance(bufsize, int):
raise TypeError("bufsize must be an integer")