* gh-141473: Fix subprocess.Popen.communicate to send input to stdin
* Docs: Clarify that `input` is one time only on `communicate()`
* NEWS entry
* Add a regression test.
---------
Co-authored-by: Gregory P. Smith <greg@krypto.org>
This flag was added as an escape hatch in gh-91401 and backported to
Python 3.10. The flag broke at some point between its addition and now.
As there is currently no publicly known environments that require this,
remove it rather than work on fixing it.
This leaves the flag in the subprocess module to not break code which
may have used / checked the flag itself.
discussion: https://discuss.python.org/t/subprocess-use-vfork-escape-hatch-broken-fix-or-remove/56915/2
GH-25416 accidentally replaced a reference to the *stderr* argument of
`subprocess.run` with a reference to the *stdin* argument. *stdin* is
not affected by the `check_output` option.
[doc] Make subprocess.wait doc more precise
An active loop is only used when the `timeout` parameter is used on
POSIX.
When no timeout is used, the code calls `os.waitpid` internally (which puts
the process on a sleep status). On Windows, the internal Windows API
call accepts a timeout parameter, so that is delegated to the OS.
On Linux where the `subprocess` module can use the `vfork` syscall for
faster spawning, prevent the parent process from blocking other threads
by dropping the GIL while it waits for the vfork'ed child process `exec`
outcome. This prevents spawning a binary from a slow filesystem from
blocking the rest of the application.
Fixes#104372.
In line 1627, the end of the sentence reads "only that that it may be." but it should read "only that it may be" (or alternatively "only that that may be").
Co-authored-by: Hugo Gabriel Eyherabide <hugogabriel.eyherabide@gmail.com>
* Note that Popen attributes aren't meant to be set by users by rewording the text about the attributes.
* Also update some universal_newlines references to mention the modern text parameter name while in the area.
Co-authored-by: Gregory P. Smith <greg@krypto.org>
* Update description of stdout, stderr, and stdin.
Changes:
- Move the ``None`` option (which is default) to the front of the list
of input options
- Move the ``None`` option description up to make the default behavior
more clear (No redirection)
- Remove mention of Child File Descriptors from ``None`` option description
One more thing that can help prevent people from using `preexec_fn`.
Also adds conditional skips to two tests exposing ASAN flakiness on the Ubuntu 20.04 Address Sanitizer Github CI system. When that build is run on more modern systems the "problem" does not show up. It seems ASAN implementation related.
Co-authored-by: Zackery Spytz <zspytz@gmail.com>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Just in case there is ever an issue with _posixsubprocess's use of
vfork() due to the complexity of using it properly and potential
directions that Linux platforms where it defaults to on could take, this
adds a failsafe so that users can disable its use entirely by setting
a global flag.
No known reason to disable it exists. But it'd be a shame to encounter
one and not be able to use CPython without patching and rebuilding it.
See the linked issue for some discussion on reasoning.
Also documents the existing way to disable posix_spawn.
Gregory P. Smith