If _BlocksOutputBuffer_Finish() fails (memory allocation failure),
PyBytesWriter_Discard() is called on the writer. Then if
_BlocksOutputBuffer_OnError() is called, it calls again
PyBytesWriter_Discard() causing a double free.
Fix _BlocksOutputBuffer_Finish() by setting buffer->writer to NULL,
so _BlocksOutputBuffer_OnError() does nothing instead of calling
PyBytesWriter_Discard() again.
gh-148653: Fix some marshal errors related to recursive immutable objects (GH-148698)
Forbid marshalling recursive code, slice and frozendict objects which
cannot be correctly unmarshalled.
Reject invalid marshal data produced by marshalling recursive frozendict
objects which was previously incorrectly unmarshalled.
Add multiple tests for recursive data structures.
gh-148651: Fix refcount leak in _zstd decompressor options (#148657)
The option parsing in Modules/_zstd/decompressor.c had a missing Py_DECREF(value) before the early return -1 when PyLong_AsInt(key) fails. The identical code in Modules/_zstd/compressor.c line 158 has the fix.
Victor Stinner [Thu, 16 Apr 2026 17:13:25 +0000 (19:13 +0200)]
gh-148535: Don't use gcc -fprofile-update=atomic flag on i686 (#148554)
The -fprofile-update=atomic flag was added to fix a random GCC
internal error on PGO build (gh-145801) caused by corruption of
profile data (.gcda files). The problem is that it makes the PGO
build way slower (up to 47x slower) on i686. Since the GCC internal
error was not seen on i686 so far, don't use -fprofile-update=atomic
on i686.
Mark Shannon [Thu, 16 Apr 2026 14:33:09 +0000 (15:33 +0100)]
GH-146128: Fix AArch64 multi-instruction constants and relocations (GH-148598)
Fix AArch64 multi-instruction constants and relocations
* Elimates rendundant orr xN, xN, 0xffff after 16 or 32 bit loads
* Merges adrp (21rx) and ldr (12) relocations into single 33rx relocation, when safe to do so.
Mark Shannon [Thu, 16 Apr 2026 14:22:22 +0000 (15:22 +0100)]
GH-145668: Add FOR_ITER specialization for virtual iterators. Specialize GET_ITER. (GH-147967)
* Add FOR_ITER_VIRTUAL to specialize FOR_ITER for virtual iterators
* Add GET_ITER_SELF to specialize GET_ITER for iterators (including generators)
* Add GET_ITER_VIRTUAL to specialize GET_ITER for iterables as virtual iterators
* Add new (internal) _tp_iteritem function slot to PyTypeObject
* Put limited RESUME at start of genexpr for free-threading. Fix up exception handling in genexpr
gh-143886: Ensure function annotations are returned in order of definition (#143888)
Ensure function annotations are returned in order of definition
Previously, when getting type annotations of a function, normal
arguments were returned before positional-only ones in the dictionary.
Since `functools.singledispatch` relies on this ordering being correct
to dispatch based on the type of the first argument, this issue was
causing incorrect registrations for functions with positional-only
arguments.
This commit updates how annotations are generated so that
positional-only arguments are generated and added to the dictionary
before normal arguments.
This option changes the behavior of --enable-shared to continue to build
the libpython3.x.so shared library, but not use it for linking the
python3 interpreter executable. Instead, the executable is linked
directly against the libpython .o files as it would be with
--disable-shared.
There are two benefits of this change. First, libpython uses
thread-local storage, which is noticeably slower when used in a loaded
module instead of in the main program, because the main program can take
advantage of constant offsets from the thread state pointer but loaded
modules have to dynamically call a function __tls_get_addr() to
potentially allocate their thread-local storage area. (There is another
thread-local storage model for dynamic libraries which mitigates most of
this performance hit, but it comes at the cost of preventing
dlopen("libpython3.x.so"), which is a use case we want to preserve.)
Second, this improves the user experience around relocatable Python a
little bit, in that we don't need to use an $ORIGIN-relative path to
locate libpython3.x.so, which has some mild benefits around musl (which
does not support $ORIGIN-relative DT_NEEDED, only $ORIGIN-relative
DT_RPATH/DT_RUNPATH), users who want to make the interpreter setuid or
setcap (which prevents processing $ORIGIN), etc.
Henry Jones [Tue, 14 Apr 2026 13:10:08 +0000 (01:10 +1200)]
gh-148192: Fix Generator._make_boundary behavior with CRLF line endings. (#148193)
The Generator._make_boundary regex did not match on boundary phrases correctly when using CRLF line endings due to re.MULTILINE not considering \r\n as a line ending.
Loïc Simon [Tue, 14 Apr 2026 11:37:41 +0000 (13:37 +0200)]
gh-134551: Add t-strings support to pprint (#134577)
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
gh-148252: Fix stack depth calculation in binary reader on 32-bit platforms (#148253)
Compute ``final_depth`` in ``decode_stack_pop_push()`` and
``decode_stack_suffix()`` using ``uint64_t`` before validating it.
On 32-bit builds, using ``size_t`` arithmetic for ``keep + push`` can wrap
for large input values, causing the later bounds check to validate the wrong
final depth. Using a widened type keeps the validation aligned with the
actual result.
gh-148178: Validate remote debug offset tables on load (#148187)
Treat the debug offset tables read from a target process as untrusted input
and validate them before the unwinder uses any reported sizes or offsets.
Add a shared validator in debug_offsets_validation.h and run it once when
_Py_DebugOffsets is loaded and once when AsyncioDebug is loaded. The checks
cover section sizes used for fixed local buffers and every offset that is
later dereferenced against a local buffer or local object view. This keeps
the bounds checks out of the sampling hot path while rejecting malformed
tables up front.
gh-144881: Add retry logic to asyncio debugging tools (#148530)
Transient errors can occur when attaching to a process that is actively
using thread delegation (e.g. asyncio.to_thread). Add a retry loop to
_get_awaited_by_tasks for RuntimeError, OSError, UnicodeDecodeError, and
MemoryError, and expose --retries CLI flag on both `ps` and `pstree`
subcommands (default: 3).
Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com> Co-authored-by: Stan Ulbrych <stan@python.org>
Joel Dice [Mon, 13 Apr 2026 21:06:36 +0000 (15:06 -0600)]
gh-146139: Disable `socketpair` authentication on WASI (#146140)
Calling `connect(2)` on a non-blocking socket on WASI may leave the socket in a
"connecting" but not yet "connected" state. In the former case, calling
`getpeername(2)` on it will fail, leading to an unhandled exception in Python.
Co-authored-by: Victor Stinner <vstinner@python.org> Co-authored-by: Brett Cannon <brett@python.org>
Sam Gross [Mon, 13 Apr 2026 18:11:28 +0000 (14:11 -0400)]
gh-148393: Use acquire load for _ma_watcher_tag in dict notify event (gh-148509)
The watcher-bits read in _PyDict_NotifyEvent needs to use acquire to
synchronize with the release from PyDict_Watch so that the callback
publication is visible before the callback is invoked.
gh-146450: Ensure Android gradle build uses custom cross-build dir (#148319)
Ensures that the testbed's Gradle configuration uses the cross-build environment
variable, and that variable is passed to Gradle by the cross-build script.
Gregory P. Smith [Sun, 12 Apr 2026 06:06:19 +0000 (23:06 -0700)]
gh-146313: Fix multiprocessing ResourceTracker deadlock after os.fork() (GH-146316)
`ResourceTracker.__del__` (added in gh-88887 circa Python 3.12) calls
os.waitpid(pid, 0) which blocks indefinitely if a process created via os.fork()
still holds the tracker pipe's write end. The tracker never sees EOF, never
exits, and the parent hangs at interpreter shutdown.
Fix with two layers:
- **At-fork handler.** An os.register_at_fork(after_in_child=...)
handler closes the inherited pipe fd in the child unless a preserve
flag is set. popen_fork.Popen._launch() sets the flag before its
fork so mp.Process(fork) children keep the fd and reuse the parent's
tracker (preserving gh-80849). Raw os.fork() children close the fd,
letting the parent reap promptly.
- **Timeout safety-net.** _stop_locked() gains a wait_timeout
parameter. When called from `__del__`, it polls with WNOHANG using
exponential backoff for up to 1 second instead of blocking
indefinitely. The at-fork handler makes this unreachable in
well-behaved paths; it remains for abnormal shutdowns.
Chris Eibl [Sun, 12 Apr 2026 05:49:18 +0000 (07:49 +0200)]
GH-148047: Check early whether tail-calling is possible for MSVC builds on Windows (#148036)
Rather than failing late when compiling e.g. a debug configuration
```
build.bat -c debug --tail-call-interp
```
with hundreds of
```
error C4737: Unable to perform required tail call. Performance may be degraded.
```
-- fail early with an explicit error message for configurations that are not supported by MSVC.
This is a follow-up on https://github.com/python/cpython/issues/140513 / https://github.com/python/cpython/pull/140548
gh-89520: Load extension settings and keybindings from user config (GH-28713)
Extension keybindings defined in ~/.idlerc/config-extensions.cfg were silently ignored because GetExtensionKeys, __GetRawExtensionKeys, and GetExtensionBindings only checked default config. Fix these to check user config as well, and update the extensions config dialog to handle user-only extensions correctly.
---------
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com> Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>
gh-147965: Add shutdown() to multiprocessing.Queue excluded methods (GH-147970)
The multiprocessing.Queue documentation states it implements all
methods of queue.Queue except task_done() and join(). Since
queue.Queue.shutdown() was added in Python 3.13,
multiprocessing.Queue also does not implement it. Update the docs
to include shutdown() in the list of excluded methods.