gc.freeze() is a new API that allows for moving all objects currently
tracked by the garbage collector to a permanent generation, effectively
removing them from future collection events. This can be used to protect
those objects from having their PyGC_Head mutated. In effect, this enables
great copy-on-write stability at fork().
Restored blocking "from package import module" by setting sys.modules["package.module"] to None.
Allow use of asynchronous generator expressions in synchronous functions.
Drop support of asynchronous __aiter__.
The -u option now makes the stdout and stderr streams unbuffered rather than line-buffered.
Fixed a ValueError when convert a string with large number of underscores to integer with binary base.
Fix an assertion failure in zipimporter.get_source() in case of a bad
zlib.decompress(). Patch by Oren Milman.
Fixed an assertion failure in Python parser in case of a bad
unicodedata.normalize(). Patch by Oren Milman.
Raise a TypeError with a helpful error message when class creation fails
due to a metaclass with a bad __prepare__() method. Patch by Oren
Milman.
Importlib was instrumented with two dtrace probes to profile import timing.
Fix an assertion failure in _warnings.warn() in case of a bad __name__
global. Patch by Oren Milman.
Improved the error message logic for object.__new__ and object.__init__.
Fix an assertion failure in json, in case _json.make_encoder() received
a bad encoder() argument. Patch by Oren Milman.
Fix assertion failures in case of failing to import from a module with a bad
__name__ attribute, and in case of failing to access an attribute of
such a module. Patch by Oren Milman.
Fix an assertion failure in _random.Random.seed() in case the argument has
a bad __abs__() method. Patch by Oren Milman.
Speed up class creation by 10-20% by reducing the overhead in the necessary special method lookups. Patch by Stefan Behnel.
Add -X importtime option to show how long each import takes. It can be
used to optimize application's startup time. Support the
:envvar:`PYTHONPROFILEIMPORTTIME` as an equivalent way to enable this.
Optimized calling wrapper and classmethod descriptors.
PEP 553 - Add a new built-in called breakpoint() which calls
sys.breakpointhook(). By default this imports pdb and calls
pdb.set_trace(), but users may override sys.breakpointhook() to call
whatever debugger they want. The original value of the hook is saved in
sys.__breakpointhook__.
Maintain a list of open buffered files, flush them before exiting the interpreter. Based on a patch from Armin Rigo.
Fix an assertion failure in imp.create_dynamic(), when spec.name is not a string. Patch by Oren Milman.
Fix a crash in the __setstate__() method of ctypes._CData, in case of
a bad __dict__. Patch by Oren Milman.
Fix crashes in true division and multiplication of a timedelta object by a float with a bad as_integer_ratio() method. Patch by Oren Milman.
Fix an assertion failure in warnings.warn_explicit, when the return value
of the received loader's get_source() has a bad splitlines() method. Patch
by Oren Milman.
Make async and await proper keywords, as specified in PEP 492.
Fixed buffer overflow in select.kqueue.control().
idpattern in string.Template matched some non-ASCII characters. Now
it uses -i regular expression local flag to avoid non-ASCII characters.
On Windows, faulthandler.enable() now ignores MSC and COM exceptions.
Prevent crashes in _elementtree due to unsafe cleanup of Element.text
and Element.tail. Patch by Oren Milman.
Now re.compile() converts passed RegexFlag to normal int object before
compiling. bm_regex_compile benchmark shows 14% performance improvements.
The types of compiled regular objects and match objects are now exposed as
re.Pattern and re.Match. This adds information in pydoc output for the
re module.
Fixed memory leaks in Tkinter's methods splitlist() and split() when pass a string larger than 2 GiB.
Fixed typo in the name of Tkinter's method adderrorinfo().
Improvements to path predicates in ElementTree: Allow whitespace around predicate parts, i.e. "[a = 'text']" instead of requiring the less readable "[a='text']". Add support for text comparison of the current node, like "[.='text']". Patch by Stefan Behnel.
Fix the string representation of a netrc object.
Add optional argument compressed to zipapp.create_archive, and add
option --compress to the command line interface of zipapp.
Avoid venv activate failures with undefined variables
Avoid ctypes use (if possible) and improve import time for uuid.
The regular expression cache is no longer completely dumped when it is full.
Added pthread_getcpuclockid() to the time module
Make 2to3 accept a trailing comma in generator expressions. For example,
set(x for x in [],) is now allowed.
Stop crashes when concurrently iterate over itertools.groupby() iterators.
An iterator produced by itertools.groupby() iterator now becomes exhausted after advancing the groupby iterator.
Cancel asyncio.wait_for future faster if timeout <= 0
Allow passing a context object in :class:`concurrent.futures.ProcessPoolExecutor` constructor. Also, free job resources in :class:`concurrent.futures.ProcessPoolExecutor` earlier to improve memory usage when a worker waits for new jobs.
threading.current_thread() should not return a dummy thread at shutdown.
In the sqlite module, require the sqlite3_prepare_v2 API. Thus, the sqlite module now requires sqlite version at least 3.3.9.
argparse subparsers are now required by default. This matches behaviour in
Python 2. For optional subparsers, use the new parameter
add_subparsers(required=False). Patch by Anthony Sottile.
(As of 3.7.0rc1, the default was changed to not required as had been the case
since Python 3.3.)
Reprs of subclasses of some collection and iterator classes (bytearray,
array.array, collections.deque, collections.defaultdict,
itertools.count, itertools.repeat) now contain actual type name instead
of hardcoded names of the base class.
python -m ensurepip now exits with non-zero exit code if pip bootstrapping has failed.
pdb.set_trace() now takes an optional keyword-only argument header.
If given, this is printed to the console just before debugging begins.
Fix incorrect usage of get_history_length in readline documentation
example code. Patch by Brad Smith.
The operator functions without double underscores are preferred for clarity. The one with underscores are only kept for back-compatibility.
Improve compiler version information in :data:`sys.version` when Python is built with Clang.
Stop using ranlib on static libraries. Instead, we assume ar supports the 's' flag.
Remove support for BSD/OS.
Prevent double substitution of prefix in python-config.sh.
Correct PCBuild/ case to PCbuild/ in build scripts and documentation.
Avoid wholesale rebuild after make regen-all if nothing changed.
Simplify the API of IDLE's Module Browser. Passing a widget instead of an flist with a root widget opens the option of creating a browser frame that is only part of a window. Passing a full file name instead of pieces assumed to come from a .py file opens the possibility of browsing python files that do not end in .py.
IDLE - Make _htest, _utest parameters keyword only.
Remove test order dependence in idle_test.test_browser.
Rename IDLE's module browser from Class Browser to Module Browser. The original module-level class and method browser became a module browser, with the addition of module-level functions, years ago. Nested classes and functions were added yesterday. For back-compatibility, the virtual event <<open-class-browser>>, which appears on the Keys tab of the Settings dialog, is not changed. Patch by Cheryl Sabella.
Default fonts now are scaled on HiDPI displays.
IDLE module browser now shows nested classes and functions. Original patches for code and tests by Guilherme Polo and Cheryl Sabella, respectively.
Make PyMapping_Keys(), PyMapping_Values() and PyMapping_Items() always
return a list (rather than a list or a tuple). Patch by Oren Milman.
Fix memory corruption due to allocator mix in getpath.c between Py_GetPath() and Py_SetPath()
Implement PEP 539 for Thread Specific Storage (TSS) API: it is a new Thread Local Storage (TLS) API to CPython which would supersede use of the existing TLS API within the CPython interpreter, while deprecating the existing API. PEP written by Erik M. Bray, patch by Masayuki Yamamoto.