파이썬 3.13의 새로운 기능에 대해 알아봅시다

편집자:

Adam Turner and Thomas Wouters

해당하는 문서는 기존의 파이썬 3.12와 비교했을 때 파이썬 3.13의 새로운 기능들에 대해 설명합니다. 파이썬 3.13은 2024년 10월 7일에 배포되었습니다. 배포와 관련된 전체 기록을 열람하시려면, 아래 변경 로그를 확인해주세요.

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PEP 719 – 파이썬 3.13 릴리스 일정

요약 – 릴리스 하이라이트

Python 3.13 is a stable release of the Python programming language, with a mix of changes to the language, the implementation and the standard library. The biggest changes include a new interactive interpreter, experimental support for running in a free-threaded mode (PEP 703), and a Just-In-Time compiler (PEP 744).

에러 메세지는 계속 개선되고 있습니다. 트레이스백(Traceback)들의 경우 기본적으로 색깔 표시됩니다. locals() 내장 함수의 경우 반환된 매핑을 변화시키기 위해 정의된 의미 구조를 활용하고, 또한 타입 매개변수들은 기본 값의 설정을 지원합니다.

표준 라이브러리의 업데이트는, 오래되어 더 이상 지원되지 않는 API들과 모듈들의 업데이트(혹은 제거)를 포함합니다. 또한, 보다 사용자 친화적이거나 보다 정확한 라이브러리가 되기 위한 통상적인 업데이트들을 포함합니다. 몇몇의 오래된 레거시 표준 라이브러리 모듈들은, 파이썬 3.11 버전에서의 사용 지원 중단(deprecate)된 이후에, 현 버전에서 제거되었습니다.

해당하는 업데이트 문서는 새로운 기능 전체에 대해서 설명을 제공해주는 것을 목적으로 삼지 않습니다. 다만, 보다 편리하게 한눈에 볼 수 있을 개괄 설명을 제공하려는 것입니다. 보다 자세한 정보를 원하신다면, 공식 문서를 참고해주세요; 예를 들어, 라이브러리 색인 혹은 언어 색인 등을 참고하실 수 있습니다. 보다 구체적인 구현 원리 혹은 디자인 원칙에 대해 이해하시고 싶으신 분들께서는, 해당하는 새로운 기능과 관련된 PEP 문서를 열람해주시기를 부탁드립니다. 다만, PEP 문서들의 경우 통상적으로 해당하는 기능이 구현되고 난 이후에는 추가적으로 업데이트되지 않아 최신화되지 않은 부분이 있을 수 있음을 양해 부탁드립니다. 과거 버전의 파이썬을 사용하는 시스템을 파이썬 3.13으로 업그레이드(혹은 이식)하기 위한 안내의 경우 Porting to Python 3.13을 참고 부탁드립니다.

인터프리터의 개선:

파이썬 데이터 모델의 개선 사항들

  • __static_attributes__는 클래스 본문 내 함수에서 self.X 형태로 액세스되는 속성의 이름을 저장합니다.

  • __firstlineno__는 클래스 정의의 첫 번째 줄 번호를 기록합니다.

표준 라이브러리의 중요한 개선 사항들:

보안 개선 사항들:

C API 개선 사항들:

  • Py_mod_gil슬롯은 확장 모듈이 GIL을 비활성화한 상태에서 실행을 지원한다는 것을 나타내기 위해 사용됩니다.

  • 시스템 시계에 액세스를 제공하는 PyTime C API가 추가되었습니다.

  • PyMutex는 1바이트만 차지하는 새로운 경량 뮤텍스(Mutex)입니다.

  • C API에 PEP 669 모니터링 이벤트를 생성하는 함수 세트가 새로 추가되었습니다.

새로운 타이핑 기능들:

플랫폼 지원:

중요한 제거 사항들:

  • PEP 594: 표준 라이브러리에서 ‘죽은 배터리(dead batteries)’로 분류된 레거시 모듈 19개가 제거되었습니다: aifc, audioop, cgi, cgitb, chunk, crypt, imghdr, mailcap, msilib, nis, nntplib, ossaudiodev, pipes, sndhdr, spwd, sunau, telnetlib, uu, xdrlib.

  • (파이썬 3.11에서 사용 지원 중단되었던) 2to3 도구와 lib2to3 모듈이 제거되었습니다.

  • (파이썬 3.6에서 사용 지원 중단되었던) tkinter.tix 모듈이 제거되었습니다.

  • locale.resetlocale() 함수가 제거되었습니다.

  • typing.io 및 typing.re 네임스페이스들이 제거되었습니다.

  • 연쇄 classmethod 설명자(descriptors)가 제거되었습니다.

릴리스 일정 변경 사항들:

PEP 602 (“Annual Release Cycle for Python”)는 새로운 릴리스의 완전 지원(‘버그 수정’) 기간을 2년으로 연장하도록 업데이트되었습니다. 이는 다음을 의미합니다:

  • Python 3.9부터 3.12 버전까지는 완전 지원 기간이 1년 반이며, 이후 3년 반 동안은 보안 수정만 제공됩니다.

  • Python 3.13 및 이후 버전은 완전 지원 기간이 2년이며, 그 후 3년간은 보안 수정만 제공합니다.

새로운 기능들

개선된 대화형 인터프리터

파이썬 3.13은 기본적으로 PyPy project의 코드를 기반으로 한 새로운 대화형 (interactive) 셸을 사용합니다. 사용자가 대화형 터미널에서 REPL을 시작하면 다음과 같은 새 기능이 지원됩니다:

  • 여러개의 줄을 편집할 때에도 기록을 보존할 수 있습니다.

  • help, exit, quit 같은 REPL 전용 명령을 직접 지원합니다. 또한, 함수로 호출할 필요 없이 사용할 수 있습니다.

  • 프롬프트와 트레이스백에서 기본적으로 색상이 활성화됩니다.

  • F1으로 대화형 도움말을 탐색할 수 있으며, 별도로 명령 기록이 제공됩니다.

  • F2로 명령 기록을 탐색할 때, 출력을 건너뛸 뿐 아니라 >>>와 … 프롬프트도 건너뜁니다.

  • F3의 “붙여넣기 모드”는 큰 코드 블록을 붙여넣기 쉽게 해 줍니다(F3를 다시 누르면 일반 프롬프트로 다시 돌아갑니다).

새 대화형 셸을 비활성화하려면 PYTHON_BASIC_REPL 환경 변수를 설정하면 됩니다. 대화형 모드에 대한 자세한 내용은 대화형 모드을 참조 부탁드립니다.

(PyPy 프로젝트의 코드를 기반으로, Pablo Galindo Salgado, Łukasz Langa, Lysandros Nikolaou가 gh-111201을 통해 기능을 구현하였습니다. Dino Viehland와 Anthony Shaw가 Windows 지원에 기여하였습니다.)

개선된 에러 메세지

  • 인터프리터는 터미널에서 트레이스백을 표시할 때 기본적으로 색상을 사용합니다. 이러한 색상 적용을 변경하기 위해 PYTHON_COLORS 환경 변수 및 NO_COLOR 및 FORCE_COLOR 환경 변수를 활용할 수 있으며, 이러한 활용을 통해 색상 적용을 제어할 수 있습니다. (Pablo Galindo Salgado가 gh-112730를 통해 기능을 구현하였습니다.)

  • 표준 라이브러리 모듈과 동일한 이름의 스크립트를 작성하는 실수는 (여러 사용자에 의해) 흔히 발생합니다. 표준 라이브러리 모듈과 동일한 이름의 스크립트로 인해 오류가 발생하는 경우에 보다 자세한 에러 메세지 제공함을 통해 보다 도움이 될 수 있도록 하였습니다:

    $ python random.py
Traceback (most recent call last):
  File "/home/me/random.py", line 1, in <module>
    import random
  File "/home/me/random.py", line 3, in <module>
    print(random.randint(5))
          ^^^^^^^^^^^^^^
AttributeError: module 'random' has no attribute 'randint' (consider renaming '/home/me/random.py' since it has the same name as the standard library module named 'random' and prevents importing that standard library module)

    또한, 스크립트가 임포트(import)하려는 제삼자(third-party) 모듈과 이름이 같아서 오류가 발생하는 경우에도 보다 자세한 에러 메세지 제공함을 통해 보다 도움이 될 수 있도록 하였습니다:

    $ python numpy.py
Traceback (most recent call last):
  File "/home/me/numpy.py", line 1, in <module>
    import numpy as np
  File "/home/me/numpy.py", line 3, in <module>
    np.array([1, 2, 3])
    ^^^^^^^^
AttributeError: module 'numpy' has no attribute 'array' (consider renaming '/home/me/numpy.py' if it has the same name as a library you intended to import)

    (Shantanu Jain이 gh-95754을 통해 기능을 구현하였습니다.)

  • 함수에 잘못된 키워드 인자가 전달되는 경우, 올바른 키워드 인자가 에러 메세지 안에서 제안되도록 하였습니다.

    >>> "Better error messages!".split(max_split=1)
Traceback (most recent call last):
  File "<python-input-0>", line 1, in <module>
    "Better error messages!".split(max_split=1)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
TypeError: split() got an unexpected keyword argument 'max_split'. Did you mean 'maxsplit'?

    (Pablo Galindo Salgado와 Shantanu Jain이 gh-107944를 통해 기능을 구현하였습니다.)

제한 없는 스레드를 사용하는 파이썬(CPython)

CPython은 전역 인터프리터 잠금 (GIL)을 비활성화한 제한 없는 스레드 모드(free-threaded mode)에서 실행을 실험적으로 지원합니다. 이는 실험적 기능이므로 기본 설정으로 활성화되어 있지는 않습니다. 제한 없는 스레드 모드를 실행시키기 위해서는 python3.13t 또는 python3.13t.exe라는 별도의 실행 파일이 필요합니다. free-threaded로 표시된 미리 빌드된 바이너리는 공식 Windows 및 macOS 설치 프로그램의 일부로 설치할 수 있으며, 또는 --disable-gil 옵션을 사용하여 소스 코드로부터 CPython을 빌드할 수 있습니다.

제한 없는 스레드 실행은 사용 가능한 CPU 코어에서 스레드를 병렬로 실행하여 가용 처리 능력을 온전히 활용할 수 있게 합니다. 모든 소프트웨어가 자동적으로 이를 통해 이점을 갖게 되는 것은 아니지만, 스레딩을 염두에 두고 설계된 프로그램은 다중 코어 하드웨어에서 보다 더 빠르게 실행됩니다. 제한 없는 스레드 모드는 실험적이며 개선 작업이 진행 중이므로, 버그가 있을 수 있으며, 단일 스레드를 통한 실행의 성능이 저하될 수 있습니다. 제한 없는 스레드를 사용하는 파이썬(CPython) 빌드는 실행 시 환경 변수 PYTHON_GIL 또는 명령줄 옵션 -X gil=1을 사용해 GIL을 활성화하여 선택적으로 실행할 수 있습니다.

사용 중인 인터프리터가 제한 없는 스레드의 사용을 지원하는지 확인하려면 python -VV 및 sys.version에서 “experimental free-threading build”를 통해 확인할 수 있습니다. 새 sys._is_gil_enabled() 함수를 사용하면 실행 중인 프로세스에서 GIL이 실제로 비활성화되어 있는지 확인할 수 있습니다.

C-API 확장 모듈은 제한 없는 스레드(free-threaded)를 사용하는 빌드용으로 따로 빌드해야 합니다. 전역 인터프리터 잠금(Global Interpreter Lock; GIL) 비활성 실행을 지원하는 확장 모듈은 Py_mod_gil 슬롯을 사용해야 합니다. 개별 단계 초기화(single-phase init)를 사용하는 확장 모듈은 GIL 비활성 실행 지원 여부를 표시하기 위해 PyUnstable_Module_SetGIL()을 사용해야 합니다. 이러한 메커니즘을 사용하지 않는 C 확장을 임포트하면 GIL이 자동으로 활성화됩니다. PYTHON_GIL 환경 변수나 -X gil=0 옵션으로 GIL을 명시적으로 비활성화한 경우는 예외입니다. 제한 없는 스레드를 사용하는 빌드에서 C 확장이 포함된 패키지를 설치하려면 pip 24.1 이상이 필요합니다.

이러한 개선 작업은 많은 개인과 조직, 그리고 제한 없는 스레드(free-threading) 사용 지원을 테스트하고 활성화하는 데 기여한 파이썬 및 다양한 제삼자(third-parth) 프로젝트 커뮤니티들 덕분이었습니다. 주목할 만한 기여자로는 Sam Gross, Ken Jin, Donghee Na, Itamar Oren, Matt Page, Brett Simmers, Dino Viehland, Carl Meyer, Nathan Goldbaum, Ralf Gommers, Lysandros Nikolaou 등이 있으며, 이외에도 많은 분들이 있습니다. 이 기여자들 중 많은 분들이 Meta에 재직하고 있으며, Meta는 이 프로젝트를 지원하기 위해 상당한 엔지니어링 자원을 제공하였습니다.

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이러한 개선 작업의 배경과 근거에 대한 보다 구체적인 정보를 위해서는 PEP 703 “Making the Global Interpreter Lock Optional in CPython”를 열람 부탁드립니다.

제한 없는 스레드 사용을 지원하기 위한 확장 모듈 이식: 커뮤니티에 의해 지원되는 제한 없는 스레드 사용 지원에 대한 이식 가이드로, 확장 모듈 작성자를 위한 가이드입니다.

실험적인 지정 시간 구동 (Just-In-Time; JIT) 컴파일러

--enable-experimental-jit 옵션을 사용하여 CPython을 구성하고 빌드하면 일부 파이썬 프로그램의 속도를 높일 수 있는 JIT 컴파일러가 추가됩니다. 윈도우에서 JIT를 활성화하려면 PCbuild/build.bat --experimental-jit을 사용하고, 2단계 (Tier 2) 인터프리터를 활성화하려면 --experimental-jit-interpreter를 사용하세요. 빌드 요구 사항과 추가 지원 정보는 Tools/jit/README.md를 확인 부탁드립니다.

--enable-experimental-jit 옵션은 다음과 같은 특정 값들을 받을 수 있습니다. 특정 값을 지정하지 않으면 기본값은 yes입니다.

  • no: 2단계 (Tier 2) 인터프리터 및 JIT 파이프라인을 모두 비활성화합니다.

  • yes: JIT (Just-In-Time; 지정 시간 구동) 컴파일러를 활성화합니다. 런타임에 JIT를 비활성화하려면 환경 변수 PYTHON_JIT=0을 설정할 수 있습니다.

  • yes-off: JIT를 빌드하되 기본값으로 비활성화합니다. 런타임에 JIT를 활성화하려면 환경 변수 PYTHON_JIT=1을 설정할 수 있습니다.

  • interpreter: 2단계 (Tier 2) 인터프리터를 활성화하지만 JIT는 비활성화합니다. 이 인터프리터는 환경 변수 PYTHON_JIT=0을 설정하여 비활성화할 수 있습니다.

내부 아키텍처는 대략적으로 다음과 같습니다:

  • 시작 지점은 최적화된 1단계(Tier 1) 바이트 코드입니다. 관련된 보다 구체적인 정보를 위해서는 3.11 버전의 새로운 기능를 열람 부탁드립니다.

  • 1단계(Tier 1) 바이트 코드가 빈번하게 실행되는 경우, 완전히 내부용인 새로운 중간 표현(IR)인 2단계 IR(Tier 2 IR)로 변환됩니다. 변환된 이러한 중간 표현은 마이크로 연산(uops)으로 명명되기도 합니다.

  • 2단계 IR도 1단계와 같은 스택 기반 가상 머신을 사용하지만, 명령어 형식의 경우 기계어로 변환하기에 보다 더 적합합니다.

  • 2단계 IR에는 여러개의 최적화 패스가 있으며, 이는 인터프리터에 의해 처리되어 실행되거나 기계어로 변환되기 전에 적용됩니다.

  • 2단계(Tier 2) 인터프리터가 있지만, 주로 앞서 서술한 최적화 파이프라인의 초기 단계를 디버깅하기 위해 만들어진 것입니다. 2단계 인터프리터는 파이썬에서 --enable-experimental-jit=interpreter 옵션을 설정함을 통해 활성화할 수 있습니다.

  • 지정 시간 구동 (JIT; Just-In-Time) 컴파일러가 활성화되면, 최적화된 2단계(Tier 2) IR이 기계어로 변환되어 실행됩니다.

  • 기계어 변환 과정에서는 복사-후-패치 (copy-and-patch)라는 기법을 사용합니다. 런타임 의존성은 없지만, 빌드의 경우 LLVM에 대한 새로운 의존성이 추가되었습니다.

더 보기

PEP 744

(JIT은 Brandt Bucher에 의해, Haoran Xu와 Fredrik Kjolstad의 논문에 영감을 받아 개발되었습니다. 2단계 IR의 경우 Mark Shannon과 Guido van Rossum에 의해 개발되었습니다. 2단계 IR의 최적화의 경우 Ken Jin에 의해 개발되었습니다.)

locals()의 변형에 대한 의미 구조 정의

지금까지 locals()의 반환값을 변경했을 때에 예상되는 결과는 개별적인 파이썬 구현에 맡겨져 있었습니다. Python 3.13부터는 PEP 667이 대부분의 코드 실행 스코프에 대해 CPython의 기존 동작을 표준화하고, 최적화된 스코프(함수, 제너레이터, 코루틴, 컴프리헨션, 제너레이터 표현식)에서는 현재 할당되어 있는 지역 변수들에 대한 서로 독립적인 스냅샷으로 명시적으로 반환하도록 변경합니다. 이는 지역적으로 참조된 비지역 변수들이 종료 시점에서 확인되는 경우을 포함합니다.

앞서 서술한 것과 같이 최적화된 스코프에서 locals()의 의미 구조가 바뀌면서, 명시적인 네임 스페이스를 제공하지 않는 경우, 암시적으로 locals()을 대상으로 실행되는 코드 실행 함수들(예: exec(), eval())의 기본 동작도 영향을 받았습니다. 이전 버전에서는 코드 실행 함수를 호출한 뒤 locals()을 호출하여 변경 사항에 액세스할 수 있는지가 구체적인 개별 구현에 따라 달라졌었습니다. 구체적으로, CPython에서 대부분의 경우 이러한 방식은 무리 없이 잘 동작하였지만, 종종 같은 스코프의 공유 스냅샷이 다른 코드(디버거나 코드 실행 추적 도구 등)에 의해 재설정될 수 있기 때문에 최적화된 스코프에서 실패하는 경우도 있었습니다. Python 3.13에서는 해당 코드를 항상 최적화된 스코프의 지역 변수에 대한 독립적인 스냅샷에 대해서만 실행하므로, 그 변경 사항은 이후의 locals() 호출에서 절대로 보이지 않습니다. 이러한 경우들에서 변경 내용을 확인하기 위해서는 관련 함수에 명시적인 네임 스페이스를 전달해야 합니다. 또는 디스크에서 파이썬 파일을 실행할 때처럼 실행 결과의 네임 스페이스를 반환하는 상위 수준의 코드 실행 API(예를 들어, runpy.run_path())로 코드를 변경하는 것이 보다 바람직할 수 있습니다.

디버거와 유사 도구들이 (앞서 서술한 변화의 영향을 받는 스코프에서) 지역 변수를 안정적으로 업데이트할 수 있도록, FrameType.f_locals는 해당 스코프의 지역 변수와 그 스코프에서 참조되는 비지역 변수에 대한 이어쓰기(write-through) 프록시를 반환합니다. 런타임 의미가 불분명하고 일관성 없이 업데이트되던 (공유된) dict 인스턴스를 반환하지 않습니다.

관련된 C API 변경 사항과 사용 지원 중단 등에 대한 보다 구체적인 정보를 위해서는 PEP 667을 열람 부탁드립니다. 또한 관련된 (코드) 이식에 대한 가이드의 경우 Python API 및 C API을 열람 부탁드립니다.

(Mark Shannon과 Tian Gao가 PEP을 작성하였고 gh-74929를 통해 기능을 구현하였습니다. Guido van Rossum과 Alyssa Coghlan이 설명서를 최신화하였습니다.)

모바일 플랫폼들에 대한 지원

PEP 730: iOS가 PEP 11에서 지원하는 플랫폼으로, arm64-apple-ios (2013년 이후 출시된 iPhone 및 iPad 기기)와 arm64-apple-ios-simulator (Apple 실리콘 하드웨어에서 실행되는 Xcode iOS 시뮬레이터)는 3단계 (Tier 3)로 지정되었습니다. x86_64-apple-ios-simulator (구형 x86_64 하드웨어에서 실행되는 Xcode iOS 시뮬레이터)는 3단계 지원 플랫폼은 아니지만, 최선의 노력(best-effort)으로 지원됩니다. (Russell Keith-Magee PEP을 작성하였고 gh-114099를 통해 기능을 구현하였습니다.)

PEP 738: Android가 PEP 11에서 지원하는 플랫폼으로, aarch64-linux-android와 x86_64-linux-android은 3단계 (Tier 3)로 지정되었습니다. 32비트 arm-linux-androideabi와 i686-linux-android는 3단계 지원 플랫폼은 아니지만, 최선의 노력(best-effort)으로 지원됩니다. (Malcolm Smith가 PEP을 작성하였고 gh-116622을 통해 기능을 구현하였습니다.)

더 보기

PEP 730, PEP 738

Other Language Changes

  • The compiler now strips common leading whitespace from every line in a docstring. This reduces the size of the bytecode cache (such as .pyc files), with reductions in file size of around 5%, for example in sqlalchemy.orm.session from SQLAlchemy 2.0. This change affects tools that use docstrings, such as doctest.

    >>> def spam():
...     """
...         This is a docstring with
...           leading whitespace.
...
...         It even has multiple paragraphs!
...     """
...
>>> spam.__doc__
'\nThis is a docstring with\n  leading whitespace.\n\nIt even has multiple paragraphs!\n'

    (Contributed by Inada Naoki in gh-81283.)

  • Annotation scopes within class scopes can now contain lambdas and comprehensions. Comprehensions that are located within class scopes are not inlined into their parent scope.

    class C[T]:
    type Alias = lambda: T

    (Contributed by Jelle Zijlstra in gh-109118 and gh-118160.)

  • Future statements are no longer triggered by relative imports of the __future__ module, meaning that statements of the form from .__future__ import ... are now simply standard relative imports, with no special features activated. (Contributed by Jeremiah Gabriel Pascual in gh-118216.)

  • global declarations are now permitted in except blocks when that global is used in the else block. Previously this raised an erroneous SyntaxError. (Contributed by Irit Katriel in gh-111123.)

  • Add PYTHON_FROZEN_MODULES, a new environment variable that determines whether frozen modules are ignored by the import machinery, equivalent to the -X frozen_modules command-line option. (Contributed by Yilei Yang in gh-111374.)

  • Add support for the perf profiler working without frame pointers through the new environment variable PYTHON_PERF_JIT_SUPPORT and command-line option -X perf_jit. (Contributed by Pablo Galindo in gh-118518.)

  • The location of a .python_history file can be changed via the new PYTHON_HISTORY environment variable. (Contributed by Levi Sabah, Zackery Spytz and Hugo van Kemenade in gh-73965.)

  • Classes have a new __static_attributes__ attribute. This is populated by the compiler with a tuple of the class’s attribute names which are assigned through self.<name> from any function in its body. (Contributed by Irit Katriel in gh-115775.)

  • The compiler now creates a __firstlineno__ attribute on classes with the line number of the first line of the class definition. (Contributed by Serhiy Storchaka in gh-118465.)

  • The exec() and eval() builtins now accept the globals and locals arguments as keywords. (Contributed by Raphael Gaschignard in gh-105879)

  • The compile() builtin now accepts a new flag, ast.PyCF_OPTIMIZED_AST, which is similar to ast.PyCF_ONLY_AST except that the returned AST is optimized according to the value of the optimize argument. (Contributed by Irit Katriel in gh-108113).

  • Add a __name__ attribute on property objects. (Contributed by Eugene Toder in gh-101860.)

  • Add PythonFinalizationError, a new exception derived from RuntimeError and used to signal when operations are blocked during finalization. The following callables now raise PythonFinalizationError, instead of RuntimeError:

    (Contributed by Victor Stinner in gh-114570.)

  • Allow the count argument of str.replace() to be a keyword. (Contributed by Hugo van Kemenade in gh-106487.)

  • Many functions now emit a warning if a boolean value is passed as a file descriptor argument. This can help catch some errors earlier. (Contributed by Serhiy Storchaka in gh-82626.)

  • Added name and mode attributes for compressed and archived file-like objects in the bz2, lzma, tarfile, and zipfile modules. (Contributed by Serhiy Storchaka in gh-115961.)

New Modules

Improved Modules

argparse

  • Add the deprecated parameter to the add_argument() and add_parser() methods, to enable deprecating command-line options, positional arguments, and subcommands. (Contributed by Serhiy Storchaka in gh-83648.)

array

  • Add the 'w' type code (Py_UCS4) for Unicode characters. It should be used instead of the deprecated 'u' type code. (Contributed by Inada Naoki in gh-80480.)

  • Register array.array as a MutableSequence by implementing the clear() method. (Contributed by Mike Zimin in gh-114894.)

ast

  • The constructors of node types in the ast module are now stricter in the arguments they accept, with more intuitive behavior when arguments are omitted.

    If an optional field on an AST node is not included as an argument when constructing an instance, the field will now be set to None. Similarly, if a list field is omitted, that field will now be set to an empty list, and if an expr_context field is omitted, it defaults to Load(). (Previously, in all cases, the attribute would be missing on the newly constructed AST node instance.)

    In all other cases, where a required argument is omitted, the node constructor will emit a DeprecationWarning. This will raise an exception in Python 3.15. Similarly, passing a keyword argument to the constructor that does not map to a field on the AST node is now deprecated, and will raise an exception in Python 3.15.

    These changes do not apply to user-defined subclasses of ast.AST unless the class opts in to the new behavior by defining the AST._field_types mapping.

    (Contributed by Jelle Zijlstra in gh-105858, gh-117486, and gh-118851.)

  • ast.parse() now accepts an optional argument optimize which is passed on to compile(). This makes it possible to obtain an optimized AST. (Contributed by Irit Katriel in gh-108113.)

asyncio

  • asyncio.as_completed() now returns an object that is both an asynchronous iterator and a plain iterator of awaitables. The awaitables yielded by asynchronous iteration include original task or future objects that were passed in, making it easier to associate results with the tasks being completed. (Contributed by Justin Arthur in gh-77714.)

  • asyncio.loop.create_unix_server() will now automatically remove the Unix socket when the server is closed. (Contributed by Pierre Ossman in gh-111246.)

  • DatagramTransport.sendto() will now send zero-length datagrams if called with an empty bytes object. The transport flow control also now accounts for the datagram header when calculating the buffer size. (Contributed by Jamie Phan in gh-115199.)

  • Add Queue.shutdown and QueueShutDown to manage queue termination. (Contributed by Laurie Opperman and Yves Duprat in gh-104228.)

  • Add the Server.close_clients() and Server.abort_clients() methods, which more forcefully close an asyncio server. (Contributed by Pierre Ossman in gh-113538.)

  • Accept a tuple of separators in StreamReader.readuntil(), stopping when any one of them is encountered. (Contributed by Bruce Merry in gh-81322.)

  • Improve the behavior of TaskGroup when an external cancellation collides with an internal cancellation. For example, when two task groups are nested and both experience an exception in a child task simultaneously, it was possible that the outer task group would hang, because its internal cancellation was swallowed by the inner task group.

    In the case where a task group is cancelled externally and also must raise an ExceptionGroup, it will now call the parent task’s cancel() method. This ensures that a CancelledError will be raised at the next await, so the cancellation is not lost.

    An added benefit of these changes is that task groups now preserve the cancellation count (cancelling()).

    In order to handle some corner cases, uncancel() may now reset the undocumented _must_cancel flag when the cancellation count reaches zero.

    (Inspired by an issue reported by Arthur Tacca in gh-116720.)

  • When TaskGroup.create_task() is called on an inactive TaskGroup, the given coroutine will be closed (which prevents a RuntimeWarning about the given coroutine being never awaited). (Contributed by Arthur Tacca and Jason Zhang in gh-115957.)

  • The function and methods named create_task have received a new **kwargs argument that is passed through to the task constructor. This change was accidentally added in 3.13.3, and broke the API contract for custom task factories. Several third-party task factories implemented workarounds for this. In 3.13.4 and later releases the old factory contract is honored once again (until 3.14). To keep the workarounds working, the extra **kwargs argument still allows passing additional keyword arguments to Task and to custom task factories.

    This affects the following function and methods: asyncio.create_task(), asyncio.loop.create_task(), asyncio.TaskGroup.create_task(). (Contributed by Thomas Grainger in gh-128307.)

base64

compileall

concurrent.futures

configparser

  • ConfigParser now has support for unnamed sections, which allows for top-level key-value pairs. This can be enabled with the new allow_unnamed_section parameter. (Contributed by Pedro Sousa Lacerda in gh-66449.)

copy

ctypes

  • As a consequence of necessary internal refactoring, initialization of internal metaclasses now happens in __init__ rather than in __new__. This affects projects that subclass these internal metaclasses to provide custom initialization. Generally:

    • Custom logic that was done in __new__ after calling super().__new__ should be moved to __init__.

    • To create a class, call the metaclass, not only the metaclass’s __new__ method.

    See gh-124520 for discussion and links to changes in some affected projects.

  • ctypes.Structure objects have a new _align_ attribute which allows the alignment of the structure being packed to/from memory to be specified explicitly. (Contributed by Matt Sanderson in gh-112433)

dbm

  • Add dbm.sqlite3, a new module which implements an SQLite backend, and make it the default dbm backend. (Contributed by Raymond Hettinger and Erlend E. Aasland in gh-100414.)

  • Allow removing all items from the database through the new clear() methods of the GDBM and NDBM database objects. (Contributed by Donghee Na in gh-107122.)

dis

  • Change the output of dis module functions to show logical labels for jump targets and exception handlers, rather than offsets. The offsets can be added with the new -O command-line option or the show_offsets argument. (Contributed by Irit Katriel in gh-112137.)

  • get_instructions() no longer represents cache entries as separate instructions. Instead, it returns them as part of the Instruction, in the new cache_info field. The show_caches argument to get_instructions() is deprecated and no longer has any effect. (Contributed by Irit Katriel in gh-112962.)

doctest

email

  • Headers with embedded newlines are now quoted on output. The generator will now refuse to serialize (write) headers that are improperly folded or delimited, such that they would be parsed as multiple headers or joined with adjacent data. If you need to turn this safety feature off, set verify_generated_headers. (Contributed by Bas Bloemsaat and Petr Viktorin in gh-121650.)

  • getaddresses() and parseaddr() now return ('', '') pairs in more situations where invalid email addresses are encountered instead of potentially inaccurate values. The two functions have a new optional strict parameter (default True). To get the old behavior (accepting malformed input), use strict=False. getattr(email.utils, 'supports_strict_parsing', False) can be used to check if the strict parameter is available. (Contributed by Thomas Dwyer and Victor Stinner for gh-102988 to improve the CVE 2023-27043 fix.)

enum

fractions

glob

  • Add translate(), a function to convert a path specification with shell-style wildcards to a regular expression. (Contributed by Barney Gale in gh-72904.)

importlib

io

ipaddress

itertools

  • batched() has a new strict parameter, which raises a ValueError if the final batch is shorter than the specified batch size. (Contributed by Raymond Hettinger in gh-113202.)

marshal

  • Add the allow_code parameter in module functions. Passing allow_code=False prevents serialization and de-serialization of code objects which are incompatible between Python versions. (Contributed by Serhiy Storchaka in gh-113626.)

math

  • The new function fma() performs fused multiply-add operations. This computes x * y + z with only a single round, and so avoids any intermediate loss of precision. It wraps the fma() function provided by C99, and follows the specification of the IEEE 754 “fusedMultiplyAdd” operation for special cases. (Contributed by Mark Dickinson and Victor Stinner in gh-73468.)

mimetypes

mmap

  • mmap is now protected from crashing on Windows when the mapped memory is inaccessible due to file system errors or access violations. (Contributed by Jannis Weigend in gh-118209.)

  • mmap has a new seekable() method that can be used when a seekable file-like object is required. The seek() method now returns the new absolute position. (Contributed by Donghee Na and Sylvie Liberman in gh-111835.)

  • The new UNIX-only trackfd parameter for mmap controls file descriptor duplication; if false, the file descriptor specified by fileno will not be duplicated. (Contributed by Zackery Spytz and Petr Viktorin in gh-78502.)

multiprocessing

os

os.path

  • Add isreserved() to check if a path is reserved on the current system. This function is only available on Windows. (Contributed by Barney Gale in gh-88569.)

  • On Windows, isabs() no longer considers paths starting with exactly one slash (\ or /) to be absolute. (Contributed by Barney Gale and Jon Foster in gh-44626.)

  • realpath() now resolves MS-DOS style file names even if the file is not accessible. (Contributed by Moonsik Park in gh-82367.)

pathlib

pdb

  • breakpoint() and set_trace() now enter the debugger immediately rather than on the next line of code to be executed. This change prevents the debugger from breaking outside of the context when breakpoint() is positioned at the end of the context. (Contributed by Tian Gao in gh-118579.)

  • sys.path[0] is no longer replaced by the directory of the script being debugged when sys.flags.safe_path is set. (Contributed by Tian Gao and Christian Walther in gh-111762.)

  • zipapp is now supported as a debugging target. (Contributed by Tian Gao in gh-118501.)

  • Add ability to move between chained exceptions during post-mortem debugging in pm() using the new exceptions [exc_number] command for Pdb. (Contributed by Matthias Bussonnier in gh-106676.)

  • Expressions and statements whose prefix is a pdb command are now correctly identified and executed. (Contributed by Tian Gao in gh-108464.)

queue

random

re

  • Rename re.error to PatternError for improved clarity. re.error is kept for backward compatibility.

shutil

  • Support the dir_fd and follow_symlinks keyword arguments in chown(). (Contributed by Berker Peksag and Tahia K in gh-62308)

site

  • .pth files are now decoded using UTF-8 first, and then with the locale encoding if UTF-8 decoding fails. (Contributed by Inada Naoki in gh-117802.)

sqlite3

ssl

statistics

  • Add kde() for kernel density estimation. This makes it possible to estimate a continuous probability density function from a fixed number of discrete samples. (Contributed by Raymond Hettinger in gh-115863.)

  • Add kde_random() for sampling from an estimated probability density function created by kde(). (Contributed by Raymond Hettinger in gh-115863.)

subprocess

  • The subprocess module now uses the posix_spawn() function in more situations.

    Notably, when close_fds is True (the default), posix_spawn() will be used when the C library provides posix_spawn_file_actions_addclosefrom_np(), which includes recent versions of Linux, FreeBSD, and Solaris. On Linux, this should perform similarly to the existing Linux vfork() based code.

    A private control knob subprocess._USE_POSIX_SPAWN can be set to False if you need to force subprocess to never use posix_spawn(). Please report your reason and platform details in the issue tracker if you set this so that we can improve our API selection logic for everyone. (Contributed by Jakub Kulik in gh-113117.)

sys

  • Add the _is_interned() function to test if a string was interned. This function is not guaranteed to exist in all implementations of Python. (Contributed by Serhiy Storchaka in gh-78573.)

tempfile

time

  • On Windows, monotonic() now uses the QueryPerformanceCounter() clock for a resolution of 1 microsecond, instead of the GetTickCount64() clock which has a resolution of 15.6 milliseconds. (Contributed by Victor Stinner in gh-88494.)

  • On Windows, time() now uses the GetSystemTimePreciseAsFileTime() clock for a resolution of 1 microsecond, instead of the GetSystemTimeAsFileTime() clock which has a resolution of 15.6 milliseconds. (Contributed by Victor Stinner in gh-63207.)

tkinter

  • Add tkinter widget methods: tk_busy_hold(), tk_busy_configure(), tk_busy_cget(), tk_busy_forget(), tk_busy_current(), and tk_busy_status(). (Contributed by Miguel, klappnase and Serhiy Storchaka in gh-72684.)

  • The tkinter widget method wm_attributes() now accepts the attribute name without the minus prefix to get window attributes, for example w.wm_attributes('alpha') and allows specifying attributes and values to set as keyword arguments, for example w.wm_attributes(alpha=0.5). (Contributed by Serhiy Storchaka in gh-43457.)

  • wm_attributes() can now return attributes as a dict, by using the new optional keyword-only parameter return_python_dict. (Contributed by Serhiy Storchaka in gh-43457.)

  • Text.count() can now return a simple int when the new optional keyword-only parameter return_ints is used. Otherwise, the single count is returned as a 1-tuple or None. (Contributed by Serhiy Storchaka in gh-97928.)

  • Support the “vsapi” element type in the element_create() method of tkinter.ttk.Style. (Contributed by Serhiy Storchaka in gh-68166.)

  • Add the after_info() method for Tkinter widgets. (Contributed by Cheryl Sabella in gh-77020.)

  • Add a new copy_replace() method to PhotoImage to copy a region from one image to another, possibly with pixel zooming, subsampling, or both. (Contributed by Serhiy Storchaka in gh-118225.)

  • Add from_coords parameter to the PhotoImage methods copy(), zoom() and subsample(). Add zoom and subsample parameters to the PhotoImage method copy(). (Contributed by Serhiy Storchaka in gh-118225.)

  • Add the PhotoImage methods read() to read an image from a file and data() to get the image data. Add background and grayscale parameters to the write() method. (Contributed by Serhiy Storchaka in gh-118271.)

traceback

types

  • SimpleNamespace can now take a single positional argument to initialise the namespace’s arguments. This argument must either be a mapping or an iterable of key-value pairs. (Contributed by Serhiy Storchaka in gh-108191.)

typing

unicodedata

venv

  • Add support for creating source control management (SCM) ignore files in a virtual environment’s directory. By default, Git is supported. This is implemented as opt-in via the API, which can be extended to support other SCMs (EnvBuilder and create()), and opt-out via the CLI, using --without-scm-ignore-files. (Contributed by Brett Cannon in gh-108125.)

warnings

xml

zipimport

  • Add support for ZIP64 format files. Everybody loves huge data, right? (Contributed by Tim Hatch in gh-94146.)

Optimizations

  • Several standard library modules have had their import times significantly improved. For example, the import time of the typing module has been reduced by around a third by removing dependencies on re and contextlib. Other modules to enjoy import-time speedups include email.utils, enum, functools, importlib.metadata, and threading. (Contributed by Alex Waygood, Shantanu Jain, Adam Turner, Daniel Hollas, and others in gh-109653.)

  • textwrap.indent() is now around 30% faster than before for large input. (Contributed by Inada Naoki in gh-107369.)

  • The subprocess module now uses the posix_spawn() function in more situations, including when close_fds is True (the default) on many modern platforms. This should provide a notable performance increase when launching processes on FreeBSD and Solaris. See the subprocess section above for details. (Contributed by Jakub Kulik in gh-113117.)

Removed Modules And APIs

PEP 594: Remove “dead batteries” from the standard library

PEP 594 proposed removing 19 modules from the standard library, colloquially referred to as ‘dead batteries’ due to their historic, obsolete, or insecure status. All of the following modules were deprecated in Python 3.11, and are now removed:

  • aifc

    • standard-aifc: Use the redistribution of aifc library from PyPI.

  • audioop

  • chunk

  • cgi and cgitb

    • cgi.FieldStorage can typically be replaced with urllib.parse.parse_qsl() for GET and HEAD requests, and the email.message module or the multipart library for POST and PUT requests.

    • cgi.parse() can be replaced by calling urllib.parse.parse_qs() directly on the desired query string, unless the input is multipart/form-data, which should be replaced as described below for cgi.parse_multipart().

    • cgi.parse_header() can be replaced with the functionality in the email package, which implements the same MIME RFCs. For example, with email.message.EmailMessage:

      from email.message import EmailMessage

msg = EmailMessage()
msg['content-type'] = 'application/json; charset="utf8"'
main, params = msg.get_content_type(), msg['content-type'].params

    • cgi.parse_multipart() can be replaced with the functionality in the email package, which implements the same MIME RFCs, or with the multipart library. For example, the email.message.EmailMessage and email.message.Message classes.

    • standard-cgi: and standard-cgitb: Use the redistribution of cgi and cgitb library from PyPI.

  • crypt and the private _crypt extension. The hashlib module may be an appropriate replacement when simply hashing a value is required. Otherwise, various third-party libraries on PyPI are available:

  • imghdr: The filetype, puremagic, or python-magic libraries should be used as replacements. For example, the puremagic.what() function can be used to replace the imghdr.what() function for all file formats that were supported by imghdr.

  • mailcap: Use the mimetypes module instead.

  • msilib

  • nis

  • nntplib: Use the pynntp library from PyPI instead.

  • ossaudiodev: For audio playback, use the pygame library from PyPI instead.

  • pipes: Use the subprocess module instead. Use shlex.quote() to replace the undocumented pipes.quote function.

  • sndhdr: The filetype, puremagic, or python-magic libraries should be used as replacements.

  • spwd: Use the python-pam library from PyPI instead.

  • sunau

  • telnetlib, Use the telnetlib3 or Exscript libraries from PyPI instead.

  • uu: Use the base64 module instead, as a modern alternative.

    • standard-uu: Use the redistribution of uu library from PyPI.

  • xdrlib

(Contributed by Victor Stinner and Zachary Ware in gh-104773 and gh-104780.)

2to3

  • Remove the 2to3 program and the lib2to3 module, previously deprecated in Python 3.11. (Contributed by Victor Stinner in gh-104780.)

builtins

  • Remove support for chained classmethod descriptors (introduced in gh-63272). These can no longer be used to wrap other descriptors, such as property. The core design of this feature was flawed and led to several problems. To “pass-through” a classmethod, consider using the __wrapped__ attribute that was added in Python 3.10. (Contributed by Raymond Hettinger in gh-89519.)

  • Raise a RuntimeError when calling frame.clear() on a suspended frame (as has always been the case for an executing frame). (Contributed by Irit Katriel in gh-79932.)

configparser

  • Remove the undocumented LegacyInterpolation class, deprecated in the docstring since Python 3.2, and at runtime since Python 3.11. (Contributed by Hugo van Kemenade in gh-104886.)

importlib.metadata

locale

  • Remove the locale.resetlocale() function, deprecated in Python 3.11. Use locale.setlocale(locale.LC_ALL, "") instead. (Contributed by Victor Stinner in gh-104783.)

opcode

  • Move opcode.ENABLE_SPECIALIZATION to _opcode.ENABLE_SPECIALIZATION. This field was added in 3.12, it was never documented, and is not intended for external use. (Contributed by Irit Katriel in gh-105481.)

  • Remove opcode.is_pseudo(), opcode.MIN_PSEUDO_OPCODE, and opcode.MAX_PSEUDO_OPCODE, which were added in Python 3.12, but were neither documented nor exposed through dis, and were not intended to be used externally. (Contributed by Irit Katriel in gh-105481.)

optparse

  • This module is no longer considered soft deprecated. While argparse remains preferred for new projects that aren’t using a third party command line argument processing library, there are aspects of the way argparse works that mean the lower level optparse module may provide a better foundation for writing argument processing libraries, and for implementing command line applications which adhere more strictly than argparse does to various Unix command line processing conventions that originate in the behaviour of the C getopt() function . (Contributed by Alyssa Coghlan and Serhiy Storchaka in gh-126180.)

pathlib

  • Remove the ability to use Path objects as context managers. This functionality was deprecated and has had no effect since Python 3.9. (Contributed by Barney Gale in gh-83863.)

re

  • Remove the undocumented, deprecated, and broken re.template() function and re.TEMPLATE / re.T flag. (Contributed by Serhiy Storchaka and Nikita Sobolev in gh-105687.)

tkinter.tix

  • Remove the tkinter.tix module, deprecated in Python 3.6. The third-party Tix library which the module wrapped is unmaintained. (Contributed by Zachary Ware in gh-75552.)

turtle

  • Remove the RawTurtle.settiltangle() method, deprecated in the documentation since Python 3.1 and at runtime since Python 3.11. (Contributed by Hugo van Kemenade in gh-104876.)

typing

  • Remove the typing.io and typing.re namespaces, deprecated since Python 3.8. The items in those namespaces can be imported directly from the typing module. (Contributed by Sebastian Rittau in gh-92871.)

  • Remove the keyword-argument method of creating TypedDict types, deprecated in Python 3.11. (Contributed by Tomas Roun in gh-104786.)

unittest

urllib

webbrowser

  • Remove the untested and undocumented MacOSX class, deprecated in Python 3.11. Use the MacOSXOSAScript class (introduced in Python 3.2) instead. (Contributed by Hugo van Kemenade in gh-104804.)

  • Remove the deprecated MacOSXOSAScript._name attribute. Use the MacOSXOSAScript.name attribute instead. (Contributed by Nikita Sobolev in gh-105546.)

New Deprecations

  • User-defined functions:

    • Deprecate assignment to a function’s __code__ attribute, where the new code object’s type does not match the function’s type. The different types are: plain function, generator, async generator, and coroutine. (Contributed by Irit Katriel in gh-81137.)

  • array:

    • Deprecate the 'u' format code (wchar_t) at runtime. This format code has been deprecated in documentation since Python 3.3, and will be removed in Python 3.16. Use the 'w' format code (Py_UCS4) for Unicode characters instead. (Contributed by Hugo van Kemenade in gh-80480.)

  • ctypes:

    • Deprecate the undocumented SetPointerType() function, to be removed in Python 3.15. (Contributed by Victor Stinner in gh-105733.)

    • Soft-deprecate the ARRAY() function in favour of type * length multiplication. (Contributed by Victor Stinner in gh-105733.)

  • decimal:

    • Deprecate the non-standard and undocumented Decimal format specifier 'N', which is only supported in the decimal module’s C implementation. (Contributed by Serhiy Storchaka in gh-89902.)

  • dis:

    • Deprecate the HAVE_ARGUMENT separator. Check membership in hasarg instead. (Contributed by Irit Katriel in gh-109319.)

  • gettext:

    • Deprecate non-integer numbers as arguments to functions and methods that consider plural forms in the gettext module, even if no translation was found. (Contributed by Serhiy Storchaka in gh-88434.)

  • glob:

    • Deprecate the undocumented glob0() and glob1() functions. Use glob() and pass a path-like object specifying the root directory to the root_dir parameter instead. (Contributed by Barney Gale in gh-117337.)

  • http.server:

    • Deprecate CGIHTTPRequestHandler, to be removed in Python 3.15. Process-based CGI HTTP servers have been out of favor for a very long time. This code was outdated, unmaintained, and rarely used. It has a high potential for both security and functionality bugs. (Contributed by Gregory P. Smith in gh-109096.)

    • Deprecate the --cgi flag to the python -m http.server command-line interface, to be removed in Python 3.15. (Contributed by Gregory P. Smith in gh-109096.)

  • mimetypes:

  • re:

    • Deprecate passing the optional maxsplit, count, or flags arguments as positional arguments to the module-level split(), sub(), and subn() functions. These parameters will become keyword-only in a future version of Python. (Contributed by Serhiy Storchaka in gh-56166.)

  • pathlib:

  • platform:

    • Deprecate java_ver(), to be removed in Python 3.15. This function is only useful for Jython support, has a confusing API, and is largely untested. (Contributed by Nikita Sobolev in gh-116349.)

  • pydoc:

    • Deprecate the undocumented ispackage() function. (Contributed by Zackery Spytz in gh-64020.)

  • sqlite3:

  • sys:

  • tarfile:

    • Deprecate the undocumented and unused TarFile.tarfile attribute, to be removed in Python 3.16. (Contributed in gh-115256.)

  • traceback:

  • typing:

    • Deprecate the undocumented keyword argument syntax for creating NamedTuple classes (e.g. Point = NamedTuple("Point", x=int, y=int)), to be removed in Python 3.15. Use the class-based syntax or the functional syntax instead. (Contributed by Alex Waygood in gh-105566.)

    • Deprecate omitting the fields parameter when creating a NamedTuple or typing.TypedDict class, and deprecate passing None to the fields parameter of both types. Python 3.15 will require a valid sequence for the fields parameter. To create a NamedTuple class with zero fields, use class NT(NamedTuple): pass or NT = NamedTuple("NT", ()). To create a TypedDict class with zero fields, use class TD(TypedDict): pass or TD = TypedDict("TD", {}). (Contributed by Alex Waygood in gh-105566 and gh-105570.)

    • Deprecate the typing.no_type_check_decorator() decorator function, to be removed in Python 3.15. After eight years in the typing module, it has yet to be supported by any major type checker. (Contributed by Alex Waygood in gh-106309.)

    • Deprecate typing.AnyStr. In Python 3.16, it will be removed from typing.__all__, and a DeprecationWarning will be emitted at runtime when it is imported or accessed. It will be removed entirely in Python 3.18. Use the new type parameter syntax instead. (Contributed by Michael The in gh-107116.)

  • wave:

Pending removal in Python 3.14

  • argparse: The type, choices, and metavar parameters of argparse.BooleanOptionalAction are deprecated and will be removed in 3.14. (Contributed by Nikita Sobolev in gh-92248.)

  • ast: The following features have been deprecated in documentation since Python 3.8, now cause a DeprecationWarning to be emitted at runtime when they are accessed or used, and will be removed in Python 3.14:

    • ast.Num

    • ast.Str

    • ast.Bytes

    • ast.NameConstant

    • ast.Ellipsis

    Use ast.Constant instead. (Contributed by Serhiy Storchaka in gh-90953.)

  • asyncio:

    • The child watcher classes asyncio.MultiLoopChildWatcher, asyncio.FastChildWatcher, asyncio.AbstractChildWatcher and asyncio.SafeChildWatcher are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in gh-94597.)

    • asyncio.set_child_watcher(), asyncio.get_child_watcher(), asyncio.AbstractEventLoopPolicy.set_child_watcher() and asyncio.AbstractEventLoopPolicy.get_child_watcher() are deprecated and will be removed in Python 3.14. (Contributed by Kumar Aditya in gh-94597.)

    • The get_event_loop() method of the default event loop policy now emits a DeprecationWarning if there is no current event loop set and it decides to create one. (Contributed by Serhiy Storchaka and Guido van Rossum in gh-100160.)

  • email: Deprecated the isdst parameter in email.utils.localtime(). (Contributed by Alan Williams in gh-72346.)

  • importlib.abc deprecated classes:

    • importlib.abc.ResourceReader

    • importlib.abc.Traversable

    • importlib.abc.TraversableResources

    Use importlib.resources.abc classes instead:

    (Contributed by Jason R. Coombs and Hugo van Kemenade in gh-93963.)

  • itertools had undocumented, inefficient, historically buggy, and inconsistent support for copy, deepcopy, and pickle operations. This will be removed in 3.14 for a significant reduction in code volume and maintenance burden. (Contributed by Raymond Hettinger in gh-101588.)

  • multiprocessing: The default start method will change to a safer one on Linux, BSDs, and other non-macOS POSIX platforms where 'fork' is currently the default (gh-84559). Adding a runtime warning about this was deemed too disruptive as the majority of code is not expected to care. Use the get_context() or set_start_method() APIs to explicitly specify when your code requires 'fork'. See 컨텍스트 및 시작 방법.

  • pathlib: is_relative_to() and relative_to(): passing additional arguments is deprecated.

  • pkgutil: pkgutil.find_loader() and pkgutil.get_loader() now raise DeprecationWarning; use importlib.util.find_spec() instead. (Contributed by Nikita Sobolev in gh-97850.)

  • pty:

  • sqlite3:

  • urllib: urllib.parse.Quoter is deprecated: it was not intended to be a public API. (Contributed by Gregory P. Smith in gh-88168.)

Pending removal in Python 3.15

  • The import system:

    • Setting __cached__ on a module while failing to set __spec__.cached is deprecated. In Python 3.15, __cached__ will cease to be set or take into consideration by the import system or standard library. (gh-97879)

    • Setting __package__ on a module while failing to set __spec__.parent is deprecated. In Python 3.15, __package__ will cease to be set or take into consideration by the import system or standard library. (gh-97879)

  • ctypes:

    • The undocumented ctypes.SetPointerType() function has been deprecated since Python 3.13.

  • http.server:

    • The obsolete and rarely used CGIHTTPRequestHandler has been deprecated since Python 3.13. No direct replacement exists. Anything is better than CGI to interface a web server with a request handler.

    • The --cgi flag to the python -m http.server command-line interface has been deprecated since Python 3.13.

  • importlib:

    • load_module() method: use exec_module() instead.

  • locale:

  • pathlib:

  • platform:

    • java_ver() has been deprecated since Python 3.13. This function is only useful for Jython support, has a confusing API, and is largely untested.

  • sysconfig:

  • threading:

    • RLock() will take no arguments in Python 3.15. Passing any arguments has been deprecated since Python 3.14, as the Python version does not permit any arguments, but the C version allows any number of positional or keyword arguments, ignoring every argument.

  • types:

  • typing:

    • The undocumented keyword argument syntax for creating NamedTuple classes (for example, Point = NamedTuple("Point", x=int, y=int)) has been deprecated since Python 3.13. Use the class-based syntax or the functional syntax instead.

    • When using the functional syntax of TypedDicts, failing to pass a value to the fields parameter (TD = TypedDict("TD")) or passing None (TD = TypedDict("TD", None)) has been deprecated since Python 3.13. Use class TD(TypedDict): pass or TD = TypedDict("TD", {}) to create a TypedDict with zero field.

    • The typing.no_type_check_decorator() decorator function has been deprecated since Python 3.13. After eight years in the typing module, it has yet to be supported by any major type checker.

  • wave:

  • zipimport:

Pending removal in Python 3.16

Pending removal in Python 3.17

  • collections.abc:

    • collections.abc.ByteString is scheduled for removal in Python 3.17.

      Use isinstance(obj, collections.abc.Buffer) to test if obj implements the buffer protocol at runtime. For use in type annotations, either use Buffer or a union that explicitly specifies the types your code supports (e.g., bytes | bytearray | memoryview).

      ByteString was originally intended to be an abstract class that would serve as a supertype of both bytes and bytearray. However, since the ABC never had any methods, knowing that an object was an instance of ByteString never actually told you anything useful about the object. Other common buffer types such as memoryview were also never understood as subtypes of ByteString (either at runtime or by static type checkers).

      See PEP 688 for more details. (Contributed by Shantanu Jain in gh-91896.)

  • typing:

    • Before Python 3.14, old-style unions were implemented using the private class typing._UnionGenericAlias. This class is no longer needed for the implementation, but it has been retained for backward compatibility, with removal scheduled for Python 3.17. Users should use documented introspection helpers like typing.get_origin() and typing.get_args() instead of relying on private implementation details.

    • typing.ByteString, deprecated since Python 3.9, is scheduled for removal in Python 3.17.

      Use isinstance(obj, collections.abc.Buffer) to test if obj implements the buffer protocol at runtime. For use in type annotations, either use Buffer or a union that explicitly specifies the types your code supports (e.g., bytes | bytearray | memoryview).

      ByteString was originally intended to be an abstract class that would serve as a supertype of both bytes and bytearray. However, since the ABC never had any methods, knowing that an object was an instance of ByteString never actually told you anything useful about the object. Other common buffer types such as memoryview were also never understood as subtypes of ByteString (either at runtime or by static type checkers).

      See PEP 688 for more details. (Contributed by Shantanu Jain in gh-91896.)

Pending removal in future versions

The following APIs will be removed in the future, although there is currently no date scheduled for their removal.

  • argparse:

    • Nesting argument groups and nesting mutually exclusive groups are deprecated.

    • Passing the undocumented keyword argument prefix_chars to add_argument_group() is now deprecated.

    • The argparse.FileType type converter is deprecated.

  • builtins:

    • Generators: throw(type, exc, tb) and athrow(type, exc, tb) signature is deprecated: use throw(exc) and athrow(exc) instead, the single argument signature.

    • Currently Python accepts numeric literals immediately followed by keywords, for example 0in x, 1or x, 0if 1else 2. It allows confusing and ambiguous expressions like [0x1for x in y] (which can be interpreted as [0x1 for x in y] or [0x1f or x in y]). A syntax warning is raised if the numeric literal is immediately followed by one of keywords and, else, for, if, in, is and or. In a future release it will be changed to a syntax error. (gh-87999)

    • Support for __index__() and __int__() method returning non-int type: these methods will be required to return an instance of a strict subclass of int.

    • Support for __float__() method returning a strict subclass of float: these methods will be required to return an instance of float.

    • Support for __complex__() method returning a strict subclass of complex: these methods will be required to return an instance of complex.

    • Delegation of int() to __trunc__() method.

    • Passing a complex number as the real or imag argument in the complex() constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in gh-109218.)

  • calendar: calendar.January and calendar.February constants are deprecated and replaced by calendar.JANUARY and calendar.FEBRUARY. (Contributed by Prince Roshan in gh-103636.)

  • codecs: use open() instead of codecs.open(). (gh-133038)

  • codeobject.co_lnotab: use the codeobject.co_lines() method instead.

  • datetime:

    • utcnow(): use datetime.datetime.now(tz=datetime.UTC).

    • utcfromtimestamp(): use datetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC).

  • gettext: Plural value must be an integer.

  • importlib:

    • cache_from_source() debug_override parameter is deprecated: use the optimization parameter instead.

  • importlib.metadata:

    • EntryPoints tuple interface.

    • Implicit None on return values.

  • logging: the warn() method has been deprecated since Python 3.3, use warning() instead.

  • mailbox: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead.

  • os: Calling os.register_at_fork() in multi-threaded process.

  • pydoc.ErrorDuringImport: A tuple value for exc_info parameter is deprecated, use an exception instance.

  • re: More strict rules are now applied for numerical group references and group names in regular expressions. Only sequence of ASCII digits is now accepted as a numerical reference. The group name in bytes patterns and replacement strings can now only contain ASCII letters and digits and underscore. (Contributed by Serhiy Storchaka in gh-91760.)

  • sre_compile, sre_constants and sre_parse modules.

  • shutil: rmtree()’s onerror parameter is deprecated in Python 3.12; use the onexc parameter instead.

  • ssl options and protocols:

    • ssl.SSLContext without protocol argument is deprecated.

    • ssl.SSLContext: set_npn_protocols() and selected_npn_protocol() are deprecated: use ALPN instead.

    • ssl.OP_NO_SSL* options

    • ssl.OP_NO_TLS* options

    • ssl.PROTOCOL_SSLv3

    • ssl.PROTOCOL_TLS

    • ssl.PROTOCOL_TLSv1

    • ssl.PROTOCOL_TLSv1_1

    • ssl.PROTOCOL_TLSv1_2

    • ssl.TLSVersion.SSLv3

    • ssl.TLSVersion.TLSv1

    • ssl.TLSVersion.TLSv1_1

  • threading methods:

  • typing.Text (gh-92332).

  • The internal class typing._UnionGenericAlias is no longer used to implement typing.Union. To preserve compatibility with users using this private class, a compatibility shim will be provided until at least Python 3.17. (Contributed by Jelle Zijlstra in gh-105499.)

  • unittest.IsolatedAsyncioTestCase: it is deprecated to return a value that is not None from a test case.

  • urllib.parse deprecated functions: urlparse() instead

    • splitattr()

    • splithost()

    • splitnport()

    • splitpasswd()

    • splitport()

    • splitquery()

    • splittag()

    • splittype()

    • splituser()

    • splitvalue()

    • to_bytes()

  • wsgiref: SimpleHandler.stdout.write() should not do partial writes.

  • xml.etree.ElementTree: Testing the truth value of an Element is deprecated. In a future release it will always return True. Prefer explicit len(elem) or elem is not None tests instead.

  • sys._clear_type_cache() is deprecated: use sys._clear_internal_caches() instead.

CPython Bytecode Changes

  • The oparg of YIELD_VALUE is now 1 if the yield is part of a yield-from or await, and 0 otherwise. The oparg of RESUME was changed to add a bit indicating if the except-depth is 1, which is needed to optimize closing of generators. (Contributed by Irit Katriel in gh-111354.)

C API Changes

새로운 기능들

Changed C APIs

Limited C API Changes

Removed C APIs

Deprecated C APIs

Pending removal in Python 3.14

Pending removal in Python 3.15

Pending removal in Python 3.16

  • The bundled copy of libmpdec.

Pending removal in Python 3.18

Pending removal in future versions

The following APIs are deprecated and will be removed, although there is currently no date scheduled for their removal.

Build Changes

  • arm64-apple-ios and arm64-apple-ios-simulator are both now PEP 11 tier 3 platforms. (PEP 730 written and implementation contributed by Russell Keith-Magee in gh-114099.)

  • aarch64-linux-android and x86_64-linux-android are both now PEP 11 tier 3 platforms. (PEP 738 written and implementation contributed by Malcolm Smith in gh-116622.)

  • wasm32-wasi is now a PEP 11 tier 2 platform. (Contributed by Brett Cannon in gh-115192.)

  • wasm32-emscripten is no longer a PEP 11 supported platform. (Contributed by Brett Cannon in gh-115192.)

  • Building CPython now requires a compiler with support for the C11 atomic library, GCC built-in atomic functions, or MSVC interlocked intrinsics.

  • Autoconf 2.71 and aclocal 1.16.5 are now required to regenerate the configure script. (Contributed by Christian Heimes in gh-89886 and by Victor Stinner in gh-112090.)

  • SQLite 3.15.2 or newer is required to build the sqlite3 extension module. (Contributed by Erlend Aasland in gh-105875.)

  • CPython now bundles the mimalloc library by default. It is licensed under the MIT license; see mimalloc license. The bundled mimalloc has custom changes, see gh-113141 for details. (Contributed by Dino Viehland in gh-109914.)

  • The configure option --with-system-libmpdec now defaults to yes. The bundled copy of libmpdec will be removed in Python 3.16.

  • Python built with configure --with-trace-refs (tracing references) is now ABI compatible with the Python release build and debug build. (Contributed by Victor Stinner in gh-108634.)

  • On POSIX systems, the pkg-config (.pc) filenames now include the ABI flags. For example, the free-threaded build generates python-3.13t.pc and the debug build generates python-3.13d.pc.

  • The errno, fcntl, grp, md5, pwd, resource, termios, winsound, _ctypes_test, _multiprocessing.posixshmem, _scproxy, _stat, _statistics, _testconsole, _testimportmultiple and _uuid C extensions are now built with the limited C API. (Contributed by Victor Stinner in gh-85283.)

Porting to Python 3.13

This section lists previously described changes and other bugfixes that may require changes to your code.

Changes in the Python API

  • PEP 667 introduces several changes to the semantics of locals() and f_locals:

    • Calling locals() in an optimized scope now produces an independent snapshot on each call, and hence no longer implicitly updates previously returned references. Obtaining the legacy CPython behavior now requires explicit calls to update the initially returned dictionary with the results of subsequent calls to locals(). Code execution functions that implicitly target locals() (such as exec and eval) must be passed an explicit namespace to access their results in an optimized scope. (Changed as part of PEP 667.)

    • Calling locals() from a comprehension at module or class scope (including via exec or eval) once more behaves as if the comprehension were running as an independent nested function (i.e. the local variables from the containing scope are not included). In Python 3.12, this had changed to include the local variables from the containing scope when implementing PEP 709. (Changed as part of PEP 667.)

    • Accessing FrameType.f_locals in an optimized scope now returns a write-through proxy rather than a snapshot that gets updated at ill-specified times. If a snapshot is desired, it must be created explicitly with dict or the proxy’s .copy() method. (Changed as part of PEP 667.)

  • functools.partial now emits a FutureWarning when used as a method. The behavior will change in future Python versions. Wrap it in staticmethod() if you want to preserve the old behavior. (Contributed by Serhiy Storchaka in gh-121027.)

  • An OSError is now raised by getpass.getuser() for any failure to retrieve a username, instead of ImportError on non-Unix platforms or KeyError on Unix platforms where the password database is empty.

  • The value of the mode attribute of gzip.GzipFile is now a string ('rb' or 'wb') instead of an integer (1 or 2). The value of the mode attribute of the readable file-like object returned by zipfile.ZipFile.open() is now 'rb' instead of 'r'. (Contributed by Serhiy Storchaka in gh-115961.)

  • mailbox.Maildir now ignores files with a leading dot (.). (Contributed by Zackery Spytz in gh-65559.)

  • pathlib.Path.glob() and rglob() now return both files and directories if a pattern that ends with “**” is given, rather than directories only. Add a trailing slash to keep the previous behavior and only match directories.

  • The threading module now expects the _thread module to have an _is_main_interpreter() function. This function takes no arguments and returns True if the current interpreter is the main interpreter.

    Any library or application that provides a custom _thread module must provide _is_main_interpreter(), just like the module’s other “private” attributes. (gh-112826.)

Changes in the C API

  • Python.h no longer includes the <ieeefp.h> standard header. It was included for the finite() function which is now provided by the <math.h> header. It should now be included explicitly if needed. Remove also the HAVE_IEEEFP_H macro. (Contributed by Victor Stinner in gh-108765.)

  • Python.h no longer includes these standard header files: <time.h>, <sys/select.h> and <sys/time.h>. If needed, they should now be included explicitly. For example, <time.h> provides the clock() and gmtime() functions, <sys/select.h> provides the select() function, and <sys/time.h> provides the futimes(), gettimeofday() and setitimer() functions. (Contributed by Victor Stinner in gh-108765.)

  • On Windows, Python.h no longer includes the <stddef.h> standard header file. If needed, it should now be included explicitly. For example, it provides offsetof() function, and size_t and ptrdiff_t types. Including <stddef.h> explicitly was already needed by all other platforms, the HAVE_STDDEF_H macro is only defined on Windows. (Contributed by Victor Stinner in gh-108765.)

  • If the Py_LIMITED_API macro is defined, Py_BUILD_CORE, Py_BUILD_CORE_BUILTIN and Py_BUILD_CORE_MODULE macros are now undefined by <Python.h>. (Contributed by Victor Stinner in gh-85283.)

  • The old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END were removed. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END.

    A tp_dealloc function that has the old macros, such as:

    static void
mytype_dealloc(mytype *p)
{
    PyObject_GC_UnTrack(p);
    Py_TRASHCAN_SAFE_BEGIN(p);
    ...
    Py_TRASHCAN_SAFE_END
}

    should migrate to the new macros as follows:

    static void
mytype_dealloc(mytype *p)
{
    PyObject_GC_UnTrack(p);
    Py_TRASHCAN_BEGIN(p, mytype_dealloc)
    ...
    Py_TRASHCAN_END
}

    Note that Py_TRASHCAN_BEGIN has a second argument which should be the deallocation function it is in. The new macros were added in Python 3.8 and the old macros were deprecated in Python 3.11. (Contributed by Irit Katriel in gh-105111.)

Regression Test Changes

  • Python built with configure --with-pydebug now supports a -X presite=package.module command-line option. If used, it specifies a module that should be imported early in the lifecycle of the interpreter, before site.py is executed. (Contributed by Łukasz Langa in gh-110769.)