Based on that code my understanding is that loading bigger structs from the future is considered okay unless `PyExpat_CAPI_MAGIC` differs, which implies that (1) magic needs to stay the same to support loading the future from the past and (2) that `PyExpat_CAPI_MAGIC` should only ever change for changes that do not increase size (but keep it constant).
To summarize, that supports your argument.
I checked branches 3.8, 3.9, 3.10, 3.11, 3.12 now and they all have the same comparison code there so reverting that magic string bump will support seamless backporting.
Sam Gross [Wed, 6 Mar 2024 14:42:11 +0000 (09:42 -0500)]
gh-115103: Delay reuse of mimalloc pages that store PyObjects (#115435)
This implements the delayed reuse of mimalloc pages that contain Python
objects in the free-threaded build.
Allocations of the same size class are grouped in data structures called
pages. These are different from operating system pages. For thread-safety, we
want to ensure that memory used to store PyObjects remains valid as long as
there may be concurrent lock-free readers; we want to delay using it for
other size classes, in other heaps, or returning it to the operating system.
When a mimalloc page becomes empty, instead of immediately freeing it, we tag
it with a QSBR goal and insert it into a per-thread state linked list of
pages to be freed. When mimalloc needs a fresh page, we process the queue and
free any still empty pages that are now deemed safe to be freed. Pages
waiting to be freed are still available for allocations of the same size
class and allocating from a page prevent it from being freed. There is
additional logic to handle abandoned pages when threads exit.
Sam Gross [Tue, 5 Mar 2024 18:54:20 +0000 (13:54 -0500)]
gh-115103: Enable internal mimalloc assertions in debug builds (#116343)
This sets `MI_DEBUG` to `2` in debug builds to enable `mi_assert_internal()`
calls. Expensive internal assertions are not enabled.
This also disables an assertion in free-threaded builds that would be
triggered by the free-threaded GC because we traverse heaps that are not
owned by the current thread.
Eric Snow [Mon, 4 Mar 2024 20:59:30 +0000 (13:59 -0700)]
gh-115490: Make the interpreter.channels and interpreter.queues Modules Handle Reloading Properly (gh-115493)
The problem manifested when the .py module got reloaded and the corresponding extension module didn't. The .py module registers types with the extension and the extension was not allowing that to happen more than once. The solution: let it happen more than once.
Brett Simmers [Mon, 4 Mar 2024 16:29:39 +0000 (08:29 -0800)]
gh-115832: Fix instrumentation version mismatch during interpreter shutdown (#115856)
A previous commit introduced a bug to `interpreter_clear()`: it set
`interp->ceval.instrumentation_version` to 0, without making the corresponding
change to `tstate->eval_breaker` (which holds a thread-local copy of the
version). After this happens, Python code can still run due to object finalizers
during a GC, and the version check in bytecodes.c will see a different result
than the one in instrumentation.c causing an infinite loop.
The fix itself is straightforward: clear `tstate->eval_breaker` when clearing
`interp->ceval.instrumentation_version`.
* Move param guard to param state machine
* Override return converter during parsing
* Don't use a custom type slot return converter; instead
special case type slot functions during generation.
Barney Gale [Mon, 4 Mar 2024 02:26:33 +0000 (02:26 +0000)]
pathlib ABCs: follow all symlinks in `PathBase.glob()` (#116293)
Switch the default value of *follow_symlinks* from `None` to `True` in
`pathlib._abc.PathBase.glob()` and `rglob()`. This speeds up recursive
globbing.
Improve algorithm for computing which rolled-over log files to delete
in logging.TimedRotatingFileHandler. It is now reliable for handlers
without namer and with arbitrary deterministic namer that leaves
the datetime part in the file name unmodified.
Marco Trevisan [Sat, 2 Mar 2024 12:48:24 +0000 (13:48 +0100)]
gh-85644: webbrowser: Use $XDG_CURRENT_DESKTOP to check desktop (GH-21731)
Usage of $GNOME_DESKTOP_SESSION_ID env variable is deprecated since
GNOME 3.30.0 [1], so should not be used, while the standard
XDG_CURRENT_DESKTOP should be instead preferred.
mpage [Fri, 1 Mar 2024 21:43:12 +0000 (13:43 -0800)]
gh-114271: Make `_thread.ThreadHandle` thread-safe in free-threaded builds (GH-115190)
Make `_thread.ThreadHandle` thread-safe in free-threaded builds
We protect the mutable state of `ThreadHandle` using a `_PyOnceFlag`.
Concurrent operations (i.e. `join` or `detach`) on `ThreadHandle` block
until it is their turn to execute or an earlier operation succeeds.
Once an operation has been applied successfully all future operations
complete immediately.
The `join()` method is now idempotent. It may be called multiple times
but the underlying OS thread will only be joined once. After `join()`
succeeds, any future calls to `join()` will succeed immediately.
The internal thread handle `detach()` method has been removed.
* Do not overwrite already rolled over files. It happened at midnight or
during the DST change and caused the loss of data.
* computeRollover() now always return the timestamp larger than the
specified time.
* Fix computation of the rollover time during the DST change.
gh-101293: Fix support of custom callables and types in inspect.Signature.from_callable() (GH-115530)
Support callables with the __call__() method and types with
__new__() and __init__() methods set to class methods, static
methods, bound methods, partial functions, and other types of
methods and descriptors.
Add tests for numerous types of callables and descriptors.
Amethyst Reese [Fri, 1 Mar 2024 10:52:53 +0000 (02:52 -0800)]
gh-116159: argparse: performance improvement parsing large number of options (#116162)
When parsing positional vs optional arguments, the use of min with a
list comprehension inside of a loop results in quadratic time based
on the number of optional arguments given. When combined with use of
prefix based argument files and a large number of optional flags, this
can result in extremely slow parsing behavior.
This replaces the min call with a simple loop with a short circuit to
break at the next optional argument.
Brett Simmers [Fri, 1 Mar 2024 01:02:12 +0000 (17:02 -0800)]
gh-116099: Fix refcounting bug in `_queueobj_shared()` (gh-116164)
This code decrefs `qidobj` twice in some paths. Since `qidobj` isn't used after
the first `Py_DECREF()`, remove the others, and replace the `Py_DECREF()` with
`Py_CLEAR()` to make it clear that the variable is dead.
With this fix, `python -mtest test_interpreters -R 3:3 -mtest_queues` no longer
fails with `_Py_NegativeRefcount: Assertion failed: object has negative ref
count`.
Malcolm Smith [Thu, 29 Feb 2024 21:58:20 +0000 (21:58 +0000)]
gh-71052: Fix several Android build issues (#115955)
This change is part of the work on PEP-738: Adding Android as a
supported platform.
* Remove the "1.0" suffix from libpython's filename on Android, which
would prevent Gradle from packaging it into an app.
* Simplify the build command in the Makefile so that libpython always
gets given an SONAME with the `-Wl-h` argument, even if the SONAME is
identical to the actual filename.
* Disable a number of functions on Android which can be compiled and
linked against, but always fail at runtime. As a result, the native
_multiprocessing module is no longer built for Android.
* gh-115390 (bee7bb331) added some pre-determined results to the
configure script for things that can't be autodetected when
cross-compiling; this change adds Android to these where appropriate.
* Add a couple more pre-determined results for Android, and making them
cover iOS as well. This means the --enable-ipv6 configure option will
no longer be required on either platform.
Guido van Rossum [Thu, 29 Feb 2024 18:55:29 +0000 (10:55 -0800)]
gh-116088: Insert bottom checks after all sym_set_...() calls (#116089)
This changes the `sym_set_...()` functions to return a `bool` which is `false`
when the symbol is `bottom` after the operation.
All calls to such functions now check this result and go to `hit_bottom`,
a special error label that prints a different message and then reports
that it wasn't able to optimize the trace. No executor will be produced
in this case.