Functions re.sub() and re.subn() and corresponding re.Pattern methods
are now 2-3 times faster for replacement strings containing group references.
Closes#91524
Primarily authored by serhiy-storchaka Serhiy Storchaka
Minor-cleanups-by: Gregory P. Smith [Google] <greg@krypto.org>
The os module and the PyUnicode_FSDecoder() function no longer accept
bytes-like paths, like bytearray and memoryview types: only the exact
bytes type is accepted for bytes strings.
Change summary:
+ There is now a `gzip.READ_BUFFER_SIZE` constant that is 128KB. Other programs that read in 128KB chunks: pigz and cat. So this seems best practice among good programs. Also it is faster than 8 kb chunks.
+ a zlib._ZlibDecompressor was added. This is the _bz2.BZ2Decompressor ported to zlib. Since the zlib.Decompress object is better for in-memory decompression, the _ZlibDecompressor is hidden. It only makes sense in file decompression, and that is already implemented now in the gzip library. No need to bother the users with this.
+ The ZlibDecompressor uses the older Cpython arrange_output_buffer functions, as those are faster and more appropriate for the use case.
+ GzipFile.read has been optimized. There is no longer a `unconsumed_tail` member to write back to padded file. This is instead handled by the ZlibDecompressor itself, which has an internal buffer. `_add_read_data` has been inlined, as it was just two calls.
EDIT: While I am adding improvements anyway, I figured I could add another one-liner optimization now to the python -m gzip application. That read chunks in io.DEFAULT_BUFFER_SIZE previously, but has been updated now to use READ_BUFFER_SIZE chunks.
On macOS, fix a crash in syslog.syslog() in multi-threaded
applications. On macOS, the libc syslog() function is not
thread-safe, so syslog.syslog() no longer releases the GIL to call
it.
Signal wakeup fd errors are now logged with
_PyErr_WriteUnraisableMsg(), rather than PySys_WriteStderr() and
PyErr_WriteUnraisable(), to pass the error message to
sys.unraisablehook. By default, it's still written into stderr (unless
sys.unraisablehook is overriden).
This seems pretty straightforward. The issue mentions other calls in mmapmodule that we could release the GIL on, but those are in methods where we'd need to be careful to ensure that something sensible happens if those are called concurrently. In prior art, note that #12073 released the GIL for munmap. In a toy benchmark, I see the speedup you'd expect from doing this.
Automerge-Triggered-By: GH:gvanrossum
* gh-96821: Fix undefined behaviour in `audioop.c`
Left-shifting negative numbers is undefined behaviour.
Fortunately, multiplication works just as well, is defined behaviour,
and gets compiled to the same machine code as before by optimizing
compilers.
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
These were intentionally skipped when operator was updated to use the argument clinic:
https://github.com/python/cpython/issues/64385#issuecomment-1093641466
However, by not using the argument clinic, they missed out on getting signatures.
This is a narrow PR to update the docstrings so that `__text_signature__` can be
extracted from them. Updating to use the argument clinic is beyond scope.
`methodcaller` uses `*args, **kwargs` to match variadic names used elsewhere,
including in `operator.call`.
The macOS 13 SDK includes support for the `mkfifoat` and `mknodat` system calls.
Using the `dir_fd` option with either `os.mkfifo` or `os.mknod` could result in a
segfault if cpython is built with the macOS 13 SDK but run on an earlier
version of macOS. Prevent this by adding runtime support for detection of
these system calls ("weaklinking") as is done for other newer syscalls on
macOS.
Fix the Python path configuration used to initialized sys.path at
Python startup. Paths are no longer encoded to UTF-8/strict to avoid
encoding errors if it contains surrogate characters (bytes paths are
decoded with the surrogateescape error handler).
getpath_basename() and getpath_dirname() functions no longer encode
the path to UTF-8/strict, but work directly on Unicode strings. These
functions now use PyUnicode_FindChar() and PyUnicode_Substring() on
the Unicode path, rather than strrchr() on the encoded bytes string.
This PR fixes undefined behaviour in the struct module unpacking support functions `bu_longlong`, `lu_longlong`, `bu_int` and `lu_int`; thanks to @kumaraditya303 for finding these.
The fix is to accumulate the bytes in an unsigned integer type instead of a signed integer type, then to convert to the appropriate signed type. In cases where the width matches, that conversion will typically be compiled away to a no-op.
(Evidence from Godbolt: https://godbolt.org/z/5zvxodj64 .)
To make the conversions efficient, I've specialised the relevant functions for their output size: for `bu_longlong` and `lu_longlong`, this only entails checking that the output size is indeed `8`. But `bu_int` and `lu_int` were used for format sizes `2` and `4` - I've split those into two separate functions each.
No tests, because all of the affected cases are already exercised by the test suite.
Serhiy Storchaka