gh-142195: Fixed Popen.communicate indefinite loops (GH-143203)
Changed condition to evaluate if timeout is less than or equals to 0. This is needed for simulated time environments such as Shadow where the time will match exactly on the boundary.
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(cherry picked from commit fa9a4254e8)
Co-authored-by: Prithviraj Chaudhuri <p.chaudhuri1993@gmail.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
gh-74389: gh-70560: subprocess.Popen.communicate() now ignores stdin.flush error when closed (GH-142061)
gh-70560: gh-74389: subprocess.Popen.communicate() now ignores stdin.flush error when closed
with a unittest and news entry.
(cherry picked from commit 923056b2d4)
Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
gh-87512: Fix `subprocess` using `timeout=` on Windows blocking with a large `input=` (GH-142058)
On Windows, Popen._communicate() previously wrote to stdin synchronously, which could block indefinitely if the subprocess didn't consume input= quickly and the pipe buffer filled up. The timeout= parameter was only checked when joining the reader threads, not during the stdin write.
This change moves the Windows stdin writing to a background thread (similar to how stdout/stderr are read in threads), allowing the timeout to be properly enforced. If timeout expires, TimeoutExpired is raised promptly and the writer thread continues in the background. Subsequent calls to communicate() will join the existing writer thread.
Adds test_communicate_timeout_large_input to verify that TimeoutExpired is raised promptly when communicate() is called with large input and a timeout, even when the subprocess doesn't consume stdin quickly.
This test already passed on POSIX (where select() is used) but failed on Windows where the stdin write blocks without checking the timeout.
(cherry picked from commit 5b1862bdd8)
Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
* gh-141473: Fix subprocess.Popen.communicate to send input to stdin upon a subsequent post-timeout call (GH-141477)
* 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.
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(cherry picked from commit 526d7a8bb4)
Co-authored-by: Artur Jamro <artur.jamro@gmail.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
* no assertStartsWith
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Co-authored-by: Artur Jamro <artur.jamro@gmail.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
GH-134453: Fix subprocess memoryview input handling on POSIX (GH-134949)
Fix inconsistent subprocess.Popen.communicate() behavior between Windows
and POSIX when using memoryview objects with non-byte elements as input.
On POSIX systems, the code was incorrectly comparing bytes written against
element count instead of byte count, causing data truncation for large
inputs with non-byte element types.
Changes:
- Cast memoryview inputs to byte view when input is already a memoryview
- Fix progress tracking to use len(input_view) instead of len(self._input)
- Add comprehensive test coverage for memoryview inputs
🤖 Generated with [Claude Code](https://claude.ai/code)
* old-man-yells-at-ReST
* Update 2025-05-30-18-37-44.gh-issue-134453.kxkA-o.rst
* assertIsNone review feedback
* fix memoryview_nonbytes test to fail without our fix on main, and have a nicer error.
Thanks to Peter Bierma @ZeroIntensity for the code review.
(cherry picked from commit cc6bc4c97f)
Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
gh-133089: Use original timeout value for `TimeoutExpired` when the func `subprocess.run` is called with a timeout (GH-133103)
(cherry picked from commit 2bbcaedb75)
Signed-off-by: Manjusaka <me@manjusaka.me>
Co-authored-by: Nadeshiko Manju <me@manjusaka.me>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
gh-129204: Add _PYTHON_SUBPROCESS_USE_POSIX_SPAWN environment knob (GH-132184)
* Add _PYTHON_SUBPROCESS_USE_POSIX_SPAWN environment knob
Add support for disabling the use of `posix_spawn` via a variable in
the process environment.
While it was previously possible to toggle this by modifying the value
of `subprocess._USE_POSIX_SPAWN`, this required either patching CPython
or modifying it within the interpreter instance which is not always
possible, such as when running applications or scripts not under a
user's control.
* fixup NEWS entry
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(cherry picked from commit 4c5dcc6d82)
Signed-off-by: Vincent Fazio <vfazio@gmail.com>
Co-authored-by: Vincent Fazio <vfazio@gmail.com>
gh-118761: Improve import time of `subprocess` (GH-129427)
* subprocess: lazy import signal and locale to improve module import time
(cherry picked from commit 49f24650e4)
Co-authored-by: Taneli Hukkinen <3275109+hukkin@users.noreply.github.com>
gh-128342: Specify timeout unit in subprocess docstrings (GH-128343)
Specify timeout unit (seconds) in subprocess docstrings
(cherry picked from commit dafe7a4463)
Co-authored-by: n-l-i <57808975+n-l-i@users.noreply.github.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Explicitly handle the case where stdout=STDOUT
as otherwise the existing error handling gets
confused and reports hard to understand errors.
Signed-off-by: Paulo Neves <ptsneves@gmail.com>
In free-threaded builds, running with `PYTHON_GIL=0` will now disable the
GIL. Follow-up issues track work to re-enable the GIL when loading an
incompatible extension, and to disable the GIL by default.
In order to support re-enabling the GIL at runtime, all GIL-related data
structures are initialized as usual, and disabling the GIL simply sets a flag
that causes `take_gil()` and `drop_gil()` to return early.
Only set filename to cwd if it was caused by failed chdir(cwd).
_fork_exec() now returns "noexec:chdir" for failed chdir(cwd).
Co-authored-by: Robert O'Shea <PurityLake@users.noreply.github.com>
Add support for `os.POSIX_SPAWN_CLOSEFROM` and
`posix_spawn_file_actions_addclosefrom_np` and have the `subprocess` module use
them when available. This means `posix_spawn` can now be used in the default
`close_fds=True` situation on many platforms.
Co-authored-by: Gregory P. Smith [Google LLC] <greg@krypto.org>
* Allow posix_spawn to inherit environment form parent environ variable.
With this change, posix_spawn call can behave similarly to execv with regards to environments when used in subprocess functions.
Refactor delete-safe symbol handling in subprocess.
Only module globals are force-cleared during interpreter finalization, using a class reference instead of individually listing the constants everywhere is simpler.
This fixes several ways file descriptors could be leaked from `subprocess.Popen` constructor during error conditions by opening them later and using a context manager "fds to close" registration scheme to ensure they get closed before returning.
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Co-authored-by: Gregory P. Smith [Google] <greg@krypto.org>
Add the -P command line option and the PYTHONSAFEPATH environment
variable to not prepend a potentially unsafe path to sys.path.
* Add sys.flags.safe_path flag.
* Add PyConfig.safe_path member.
* Programs/_bootstrap_python.c uses config.safe_path=0.
* Update subprocess._optim_args_from_interpreter_flags() to handle
the -P command line option.
* Modules/getpath.py sets safe_path to 1 if a "._pth" file is
present.
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.
Removes the `list` call in the Popen `repr`.
Current implementation:
For cmd = `python --version`, with `shell=True`.
```bash
<Popen: returncode: None args: ['p', 'y', 't', 'h', 'o', 'n', ' ', '-', '-',...>
```
For `shell=False` and args=`['python', '--version']`, the output is correct:
```bash
<Popen: returncode: None args: ['python', '--version']>
```
With the new changes the `repr` yields:
For cmd = `python --version`, with `shell=True`:
```bash
<Popen: returncode: None args: 'python --version'>
```
For `shell=False` and args=`['python', '--version']`, the output:
```bash
<Popen: returncode: None args: ['python', '--version']>
```
Automerge-Triggered-By: GH:gpshead
See [PEP 597](https://www.python.org/dev/peps/pep-0597/).
* Add `-X warn_default_encoding` and `PYTHONWARNDEFAULTENCODING`.
* Add EncodingWarning
* Add io.text_encoding()
* open(), TextIOWrapper() emits EncodingWarning when encoding is omitted and warn_default_encoding is enabled.
* _pyio.TextIOWrapper() uses UTF-8 as fallback default encoding used when failed to import locale module. (used during building Python)
* bz2, configparser, gzip, lzma, pathlib, tempfile modules use io.text_encoding().
* What's new entry
Check to make sure stdout and stderr are not empty before selecting an item from them in Windows subprocess._communicate.
Co-authored-by: Gregory P. Smith <greg@krypto.org>
When the modern text= spelling of the universal_newlines= parameter was added
for Python 3.7, check_output's special case around input=None was overlooked.
So it behaved differently with universal_newlines=True vs text=True. This
reconciles the behavior to be consistent and adds a test to guarantee it.
Also clarifies the existing check_output documentation.
Co-authored-by: Alexey Izbyshev <izbyshev@ispras.ru>
send_signal() now swallows the exception if the process it thought was still alive winds up not to exist anymore (always a plausible race condition despite the checks).
Co-authored-by: Gregory P. Smith <greg@krypto.org>
* Add F_SETPIPE_SZ and F_GETPIPE_SZ to fcntl module
* Add pipesize parameter for subprocess.Popen class
This will allow the user to control the size of the pipes.
On linux the default is 64K. When a pipe is full it blocks for writing.
When a pipe is empty it blocks for reading. On processes that are
very fast this can lead to a lot of wasted CPU cycles. On a typical
Linux system the max pipe size is 1024K which is much better.
For high performance-oriented libraries such as xopen it is nice to
be able to set the pipe size.
The workaround without this feature is to use my_popen_process.stdout.fileno() in
conjuction with fcntl and 1031 (value of F_SETPIPE_SZ) to acquire this behavior.
This commit removes the old parser, the deprecated parser module, the old parser compatibility flags and environment variables and all associated support code and documentation.
* Rename PyConfig.use_peg to _use_peg_parser
* Document PyConfig._use_peg_parser and mark it a deprecated
* Mark -X oldparser option and PYTHONOLDPARSER env var as deprecated
in the documentation.
* Add use_old_parser() and skip_if_new_parser() to test.support
* Remove sys.flags.use_peg: use_old_parser() uses
_testinternalcapi.get_configs() instead.
* Enhance test_embed tests
* subprocess._args_from_interpreter_flags() copies -X oldparser
This implements things like `list[int]`,
which returns an object of type `types.GenericAlias`.
This object mostly acts as a proxy for `list`,
but has attributes `__origin__` and `__args__`
that allow recovering the parts (with values `list` and `(int,)`.
There is also an approximate notion of type variables;
e.g. `list[T]` has a `__parameters__` attribute equal to `(T,)`.
Type variables are objects of type `typing.TypeVar`.
Add os.waitstatus_to_exitcode() function to convert a wait status to an
exitcode.
Suggest waitstatus_to_exitcode() usage in the documentation when
appropriate.
Use waitstatus_to_exitcode() in:
* multiprocessing, os, subprocess and _bootsubprocess modules;
* test.support.wait_process();
* setup.py: run_command();
* and many tests.
Miss Islington (bot)