Add documentation for the F (complex from two floats) and D (complex
from two doubles) format characters in the struct module docstring.
These format characters were implemented but not documented.
Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
Previously, negative timestamps (representing dates before 1970-01-01) were
not supported on Windows due to platform limitations. The changes introduce a
fallback implementation using the Windows FILETIME API, allowing negative
timestamps to be correctly handled in both UTC and local time conversions.
Additionally, related test code is updated to remove Windows-specific skips
and error handling, ensuring consistent behavior across platforms.
Co-authored-by: Victor Stinner <vstinner@python.org>
Add the unicodedata.iter_graphemes() function to iterate over grapheme
clusters according to rules defined in Unicode Standard Annex #29.
Add unicodedata.grapheme_cluster_break(), unicodedata.indic_conjunct_break()
and unicodedata.extended_pictographic() functions to get the properties
of the character which are related to the above algorithm.
Co-authored-by: Guillaume "Vermeille" Sanchez <guillaume.v.sanchez@gmail.com>
The internal encoder object returned by undocumented function
json.encoder.c_make_encoder() (aka _json.make_encoder()) crashed
when it was called with non-zero second argument.
The 'exc' field was used by our debug SSL callbacks. Keep the exception
in the normal per-thread state to avoid shared mutable state between
threads.
This also avoids a reference count leak if the Python callback raised an
exception because it can be called multiple times per SSL operation.
PyObject_GetBuffer() can execute user code (e.g. via __buffer__), which may
close or otherwise mutate a BytesIO object while write() or writelines()
is in progress. This could invalidate the internal buffer and lead to a
use-after-free.
Ensure that PyObject_GetBuffer() is called before validation checks.
When using blocking mode in the remote debugging profiler, ptrace calls
to seize threads can fail with EPERM if the thread has exited between
listing and attaching, is in a special kernel state, or is already being
traced. Previously this raised a RuntimeError that was caught by the
Python sampling loop,and retried indefinitely since EPERM is
a persistent condition that will not resolve on its own.
Treat EPERM the same as ESRCH by returning 1 (skip this thread) instead
of -1 (fatal error). This allows profiling to continue with the threads
that can be traced rather than entering an endless retry loop printing
the same error message repeatedly.
Optimize base64 encoding/decoding by eliminating loop-carried dependencies. Key changes:
- Add `base64_encode_trio()` and `base64_decode_quad()` helper functions that process complete groups independently
- Add `base64_encode_fast()` and `base64_decode_fast()` wrappers
- Update `b2a_base64` and `a2b_base64` to use fast path for complete groups
Performance gains (encode/decode speedup vs main, PGO builds):
```
64 bytes 64K 1M
Zen2: 1.2x/1.8x 1.7x/2.8x 1.5x/2.8x
Zen4: 1.2x/1.7x 1.6x/3.0x 1.5x/3.0x [old data, likely faster]
M4: 1.3x/1.9x 2.3x/2.8x 2.4x/2.9x [old data, likely faster]
RPi5-32: 1.2x/1.2x 2.4x/2.4x 2.0x/2.1x
```
Based on my exploratory work done in https://github.com/python/cpython/compare/main...gpshead:cpython:claude/vectorize-base64-c-S7Hku
See PR and issue for further thoughts on sometimes MUCH faster SIMD vectorized versions of this.
