Not comprehensive, best effort warning. There are cases when threads exist on some platforms that this code cannot detect. macOS when API permissions allow and Linux with a readable /proc procfs present are the currently supported cases where a warning should show up reliably.
Starting with a DeprecationWarning for now, it is less disruptive than something like RuntimeWarning and most likely to only be seen in people's CI tests - a good place to start with this messaging.
Previously, the optional restrictions on subinterpreters were: disallow fork, subprocess, and threads. By default, we were disallowing all three for "isolated" interpreters. We always allowed all three for the main interpreter and those created through the legacy `Py_NewInterpreter()` API.
Those settings were a bit conservative, so here we've adjusted the optional restrictions to: fork, exec, threads, and daemon threads. The default for "isolated" interpreters disables fork, exec, and daemon threads. Regular threads are allowed by default. We continue always allowing everything For the main interpreter and the legacy API.
In the code, we add `_PyInterpreterConfig.allow_exec` and `_PyInterpreterConfig.allow_daemon_threads`. We also add `Py_RTFLAGS_DAEMON_THREADS` and `Py_RTFLAGS_EXEC`.
* gh-93503: Add APIs to set profiling and tracing functions in all threads in the C-API
* Use a separate API
* Fix NEWS entry
* Add locks around the loop
* Document ignoring exceptions
* Use the new APIs in the sys module
* Update docs
Join the thread to not leak threads running in the background to the
next test.
Fix the following warning on the "AMD64 FreeBSD Shared 3.11"
buildbot:
test_args_argument (test.test_threading.ThreadTests.test_args_argument) ...
Warning -- threading_cleanup() failed to cleanup 1 threads (count: 1, dangling: 2)
Warning -- Dangling thread: <_MainThread(MainThread, started 35026161664)>
Warning -- Dangling thread: <Thread(Thread-134 (<lambda>), started 35314998016)>
ok
For threads, and for multiprocessing, it's always been the case that ``args=list`` works fine when passed to ``Process()`` or ``Thread()``, and such code is common in the wild. But, according to the docs, only a tuple can be used. This brings the docs into synch with reality.
Doc changes by Charlie Zhao.
Co-authored-by: Tim Peters <tim.peters@gmail.com>
Fix the threading._shutdown() function when the threading module was
imported first from a thread different than the main thread: no
longer log an error at Python exit.
Doing this provides significant performance gains for runtime startup (~15% with all the imported modules frozen). We don't yet freeze all the imported modules because there are a few hiccups in the build systems we need to sort out first. (See bpo-45186 and bpo-45188.)
Note that in PR GH-28320 we added a command-line flag (-X frozen_modules=[on|off]) that allows users to opt out of (or into) using frozen modules. The default is still "off" but we will change it to "on" as soon as we can do it in a way that does not cause contributors pain.
https://bugs.python.org/issue45020
The threading debug (PYTHONTHREADDEBUG environment variable) is
deprecated in Python 3.10 and will be removed in Python 3.12. This
feature requires a debug build of Python.
When a Thread is not joined after it has stopped, its lock may remain in the _shutdown_locks set until interpreter shutdown. If many threads are created this way, the _shutdown_locks set could therefore grow endlessly. To avoid such a situation, purge expired locks each time a new one is added or removed.
test.libregrtest now marks a test as ENV_CHANGED (altered the
execution environment) if a thread raises an exception but does not
catch it. It sets a hook on threading.excepthook. Use
--fail-env-changed option to mark the test as failed.
libregrtest regrtest_unraisable_hook() explicitly flushs
sys.stdout, sys.stderr and sys.__stderr__.
The snake_case names have existed since Python 2.6, so there is
no reason to keep the old camelCase names around. One similar
method, threading.Thread.isAlive, was already removed in
Python 3.9 (bpo-37804).
At Python exit, if a callback registered with atexit.register()
fails, its exception is now logged. Previously, only some exceptions
were logged, and the last exception was always silently ignored.
Add _PyAtExit_Call() function and remove
PyInterpreterState.atexit_func member. call_py_exitfuncs() now calls
directly _PyAtExit_Call().
The atexit module must now always be built as a built-in module.
Fix the threading.Thread class at fork: do nothing if the thread is
already stopped (ex: fork called at Python exit). Previously, an
error was logged in the child process.
* Rewrite test_thread.test_forkinthread() to use
support.wait_process() and wait for the child process in the main
thread, not in the spawned thread.
* test_threading now uses support.wait_process() and checks the child
process exit code to detect crashes.
Remove daemon threads from :mod:`concurrent.futures` by adding
an internal `threading._register_atexit()`, which calls registered functions
prior to joining all non-daemon threads. This allows for compatibility
with subinterpreters, which don't support daemon threads.
PyThreadState.frame is a borrowed reference, not a strong reference:
PyThreadState_Clear() must not call Py_CLEAR(tstate->frame).
Remove test_threading.test_warnings_at_exit(): we cannot warranty
that the Python thread state of daemon threads is cleared in a
reliable way during Python shutdown.
Clear the frames of daemon threads earlier during the Python shutdown to
call objects destructors. So "unclosed file" resource warnings are now
emitted for daemon threads in a more reliable way.
Cleanup _PyThreadState_DeleteExcept() code: rename "garbage" to
"list".
Replace hardcoded timeout constants in tests with SHORT_TIMEOUT of
test.support, so it's easier to ajdust this timeout for all tests at
once.
SHORT_TIMEOUT is 30 seconds by default, but it can be longer
depending on --timeout command line option.
The change makes almost all timeouts longer, except
test_reap_children() of test_support which is made 2x shorter:
SHORT_TIMEOUT should be enough. If this test starts to fail,
LONG_TIMEOUT should be used instead.
Uniformize also "from test import support" import in some test files.
This changeset increases the default size of the stack
for threads on macOS to the size of the stack
of the main thread and reenables the relevant
recursion test.
In a subinterpreter, spawning a daemon thread now raises an
exception. Daemon threads were never supported in subinterpreters.
Previously, the subinterpreter finalization crashed with a Pyton
fatal error if a daemon thread was still running.
* Add _thread._is_main_interpreter()
* threading.Thread.start() now raises RuntimeError if the thread is a
daemon thread and the method is called from a subinterpreter.
* The _thread module now uses Argument Clinic for the new function.
* Use textwrap.dedent() in test_threading.SubinterpThreadingTests
Fix a race condition at Python shutdown when waiting for threads.
Wait until the Python thread state of all non-daemon threads get
deleted (join all non-daemon threads), rather than just wait until
Python threads complete.
* Add threading._shutdown_locks: set of Thread._tstate_lock locks
of non-daemon threads used by _shutdown() to wait until all Python
thread states get deleted. See Thread._set_tstate_lock().
* Add also threading._shutdown_locks_lock to protect access to
threading._shutdown_locks.
* Add test_finalization_shutdown() test.
Add a new threading.excepthook() function which handles uncaught
Thread.run() exception. It can be overridden to control how uncaught
exceptions are handled.
threading.ExceptHookArgs is not documented on purpose: it should not
be used directly.
* threading.excepthook() and threading.ExceptHookArgs.
* Add _PyErr_Display(): similar to PyErr_Display(), but accept a
'file' parameter.
* Add _thread._excepthook(): C implementation of the exception hook
calling _PyErr_Display().
* Add _thread._ExceptHookArgs: structseq type.
* Add threading._invoke_excepthook_wrapper() which handles the gory
details to ensure that everything remains alive during Python
shutdown.
* Add unit tests.
Gregory P. Smith
Eric Snow
Pablo Galindo Salgado
Victor Stinner
Christian Heimes
Charlie Zhao
Mark Shannon
Erlend Egeberg Aasland
uniocto
Antoine Pitrou
Jelle Zijlstra
BarneyStratford
Mario Corchero
Hai Shi
Kyle Stanley
Victor Stinner
Dong-hee Na
Ronald Oussoren
Min ho Kim
Matěj Cepl