There is a race between when `Thread._tstate_lock` is released[^1] in `Thread._wait_for_tstate_lock()`
and when `Thread._stop()` asserts[^2] that it is unlocked. Consider the following execution
involving threads A, B, and C:
1. A starts.
2. B joins A, blocking on its `_tstate_lock`.
3. C joins A, blocking on its `_tstate_lock`.
4. A finishes and releases its `_tstate_lock`.
5. B acquires A's `_tstate_lock` in `_wait_for_tstate_lock()`, releases it, but is swapped
out before calling `_stop()`.
6. C is scheduled, acquires A's `_tstate_lock` in `_wait_for_tstate_lock()` but is swapped
out before releasing it.
7. B is scheduled, calls `_stop()`, which asserts that A's `_tstate_lock` is not held.
However, C holds it, so the assertion fails.
The race can be reproduced[^3] by inserting sleeps at the appropriate points in
the threading code. To do so, run the `repro_join_race.py` from the linked repo.
There are two main parts to this PR:
1. `_tstate_lock` is replaced with an event that is attached to `PyThreadState`.
The event is set by the runtime prior to the thread being cleared (in the same
place that `_tstate_lock` was released). `Thread.join()` blocks waiting for the
event to be set.
2. `_PyInterpreterState_WaitForThreads()` provides the ability to wait for all
non-daemon threads to exit. To do so, an `is_daemon` predicate was added to
`PyThreadState`. This field is set each time a thread is created. `threading._shutdown()`
now calls into `_PyInterpreterState_WaitForThreads()` instead of waiting on
`_tstate_lock`s.
[^1]: 441affc9e7/Lib/threading.py (L1201)
[^2]: 441affc9e7/Lib/threading.py (L1115)
[^3]: 8194653279
---------
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Antoine Pitrou <antoine@python.org>
Change automatically generated tkinter.Checkbutton widget names to
avoid collisions with automatically generated tkinter.ttk.Checkbutton
widget names within the same parent widget.
* Restore support of None and other false values.
* Raise TypeError for non-zero integers and non-empty sequences.
The regressions were introduced in gh-74668
(bdba8ef42b).
Any capitalization of "xn--" should be acceptable for the ACE prefix
(see https://tools.ietf.org/html/rfc3490#section-5).
Co-authored-by: Pepijn de Vos <pepijndevos@gmail.com>
Co-authored-by: Erlend E. Aasland <erlend@python.org>
Co-authored-by: Petr Viktorin <encukou@gmail.com>
The test case had a race condition: if `q.task_done()` was executed
after `shutdown(immediate=True)`, then it would raise an exception
because the immediate shutdown already emptied the queue. This happened
rarely with the GIL (due to the switching interval), but frequently in
the free-threaded build.
The free-threaded GC only does full collections, so it uses a threshold that
is a maximum of a fixed value (default 2000) and proportional to the number of
live objects. If there were many live objects after the previous collection,
then the threshold may be larger than 10,000 causing
`test_indirect_calls_with_gc_disabled` to fail.
This manually sets the threshold to `(1000, 0, 0)` for the test. The `0`
disables the proportional scaling.
test_match_tests now saves and restores patterns.
Add get_match_tests() function to libregrtest.filter.
Previously, running test_regrtest multiple times in a row only ran
tests once: "./python -m test test_regrtest -R 3:3.
* GH-116554: Relax list.sort()'s notion of "descending" run
Rewrote `count_run()` so that sub-runs of equal elements no longer end a descending run. Both ascending and descending runs can have arbitrarily many sub-runs of arbitrarily many equal elements now. This is tricky, because we only use ``<`` comparisons, so checking for equality doesn't come "for free". Surprisingly, it turned out there's a very cheap (one comparison) way to determine whether an ascending run consisted of all-equal elements. That sealed the deal.
In addition, after a descending run is reversed in-place, we now go on to see whether it can be extended by an ascending run that just happens to be adjacent. This succeeds in finding at least one additional element to append about half the time, and so appears to more than repay its cost (the savings come from getting to skip a binary search, when a short run is artificially forced to length MIINRUN later, for each new element `count_run()` can add to the initial run).
While these have been in the back of my mind for years, a question on StackOverflow pushed it to action:
https://stackoverflow.com/questions/78108792/
They were wondering why it took about 4x longer to sort a list like:
[999_999, 999_999, ..., 2, 2, 1, 1, 0, 0]
than "similar" lists. Of course that runs very much faster after this patch.
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
gh-116307: Create a new import helper 'isolated modules' and use that instead of 'Clean Import' to ensure that tests from importlib_resources don't leave modules in sys.modules.
* and fix global flag repr
* Update Misc/NEWS.d/next/Library/2024-03-11-12-11-10.gh-issue-116600.FcNBy_.rst
Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
These give applications the option of more forcefully terminating client
connections for asyncio servers. Useful when terminating a service and
there is limited time to wait for clients to finish up their work.
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.
Move the following files from Modules/_testcapi/ to
Modules/_testlimitedcapi/:
* bytearray.c
* bytes.c
* pyos.c
* sys.c
Changes:
* Replace PyBytes_AS_STRING() with PyBytes_AsString().
* Replace PyBytes_GET_SIZE() with PyBytes_Size().
* Update related test_capi tests.
* Copy Modules/_testcapi/util.h to Modules/_testlimitedcapi/util.h.
The tests failed (with less than 1% probability) if for example the file
was created at 11:46:03.999, but the record was emitted at 11:46:04.001,
with atTime=11:46:04, which caused an unexpected rollover. Ensure that the
tests are always run within the range of the same whole second.
Also share code between test_rollover_at_midnight and test_rollover_at_weekday.
