3. 配置 Python

3.1. Build Requirements

Features required to build CPython:

• A C11 compiler. Optional C11 features are not required.

• Support for IEEE 754 floating point numbers and floating point Not-a-Number (NaN).

• thread 的支援。

• OpenSSL 1.1.1 or newer for the ssl and hashlib modules.

• 在 Windows 上需要 Microsoft Visual Studio 2017 或更新版本。

在 3.11 版的變更: C11 compiler, IEEE 754 and NaN support are now required. On Windows, Visual Studio 2017 or later is required.

在 3.10 版的變更: OpenSSL 1.1.1 現在是必要的。

在 3.7 版的變更: 對執行緒與 OpenSSL 1.0.2 的支援現在是必要的。

在 3.6 版的變更: Selected C99 features are now required, like <stdint.h> and static inline functions.

在 3.5 版的變更: 在 Windows 上需要 Visual Studio 2015 或更新版本。

See also PEP 7 "Style Guide for C Code" and PEP 11 "CPython platform support".

3.2. 產生的檔案

To reduce build dependencies, Python source code contains multiple generated files. Commands to regenerate all generated files:

make regen-all
make regen-stdlib-module-names
make regen-limited-abi
make regen-configure

The Makefile.pre.in file documents generated files, their inputs, and tools used to regenerate them. Search for regen-* make targets.

3.2.1. 設定腳本

The make regen-configure command regenerates the aclocal.m4 file and the configure script using the Tools/build/regen-configure.sh shell script which uses an Ubuntu container to get the same tools versions and have a reproducible output.

The container is optional, the following command can be run locally:

autoreconf -ivf -Werror

The generated files can change depending on the exact autoconf-archive, aclocal and pkg-config versions.

3.3. 設定選項

List all ./configure script options using:

./configure --help

請見 Python 原始碼發行版中的 Misc/SpecialBuilds.txt。

3.3.1. 一般選項

--enable-loadable-sqlite-extensions

Support loadable extensions in the _sqlite extension module (default is no) of the sqlite3 module.

請見 sqlite3 模組的 sqlite3.Connection.enable_load_extension() 方法。

在 3.6 版新加入.

--disable-ipv6

停用 IPv6 支援（如果支援的話預設是啟用的），請見 socket 模組。

--enable-big-digits=[15|30]

Define the size in bits of Python int digits: 15 or 30 bits.

By default, the digit size is 30.

將 PYLONG_BITS_IN_DIGIT 定義為 15 或 30。

參閱 sys.int_info.bits_per_digit。

--with-suffix=SUFFIX

將 Python 執行檔的後綴設定為 SUFFIX。

在 Windows 和 macOS 上預設的後綴是 .exe （python.exe 執行檔）、在 Emscripten node 上為 .js、在 Emscripten 瀏覽器為 .html、在 WASI 上為 .wasm，以及在其他平台為空字串（python 執行檔）。

在 3.11 版的變更: 在 WASM 平台上預設的後綴是 .js、.html 或 .wasm 中的一個。

--with-tzpath=<list of absolute paths separated by pathsep>

Select the default time zone search path for zoneinfo.TZPATH. See the Compile-time configuration of the zoneinfo module.

預設值：/usr/share/zoneinfo:/usr/lib/zoneinfo:/usr/share/lib/zoneinfo:/etc/zoneinfo。

請見 os.pathsep 路徑分隔符號。

在 3.9 版新加入.

--without-decimal-contextvar

Build the _decimal extension module using a thread-local context rather than a coroutine-local context (default), see the decimal module.

請見 decimal.HAVE_CONTEXTVAR 與 contextvars 模組。

在 3.9 版新加入.

--with-dbmliborder=<list of backend names>

Override order to check db backends for the dbm module

A valid value is a colon (:) separated string with the backend names:

• ndbm;

• gdbm;

• bdb.

--without-c-locale-coercion

Disable C locale coercion to a UTF-8 based locale (enabled by default).

不要定義 PY_COERCE_C_LOCALE 巨集。

請見 PYTHONCOERCECLOCALE 與 PEP 538。

--without-freelists

Disable all freelists except the empty tuple singleton.

在 3.11 版新加入.

--with-platlibdir=DIRNAME

Python 函式庫目錄名稱（預設為 lib ）。

Fedora 和 SuSE 在 64 位元平台上使用 lib64。

參閱 sys.platlibdir。

在 3.9 版新加入.

--with-wheel-pkg-dir=PATH

Directory of wheel packages used by the ensurepip module (none by default).

Some Linux distribution packaging policies recommend against bundling dependencies. For example, Fedora installs wheel packages in the /usr/share/python-wheels/ directory and don't install the ensurepip._bundled package.

在 3.10 版新加入.

--with-pkg-config=[check|yes|no]

Whether configure should use pkg-config to detect build dependencies.

• check （預設）：pkg-config 是可選的

• yes：pkg-config 是必要的

• no：即使存在也不使用 pkg-config 來配置

在 3.11 版新加入.

--enable-pystats

Turn on internal statistics gathering.

The statistics will be dumped to a arbitrary (probably unique) file in /tmp/py_stats/, or C:\temp\py_stats\ on Windows. If that directory does not exist, results will be printed on stdout.

使用 Tools/scripts/summarize_stats.py 來讀取統計資料。

在 3.11 版新加入.

3.3.2. WebAssembly 選項

--with-emscripten-target=[browser|node]

Set build flavor for wasm32-emscripten.

• browser (default): preload minimal stdlib, default MEMFS.

• node：對 NODERAWFS 和 pthread 支援。

在 3.11 版新加入.

--enable-wasm-dynamic-linking

Turn on dynamic linking support for WASM.

Dynamic linking enables dlopen. File size of the executable increases due to limited dead code elimination and additional features.

在 3.11 版新加入.

--enable-wasm-pthreads

Turn on pthreads support for WASM.

在 3.11 版新加入.

3.3.3. 安裝選項

--prefix=PREFIX

Install architecture-independent files in PREFIX. On Unix, it defaults to /usr/local.

這個值可以在 runtime 使用 sys.prefix 取得。

As an example, one can use --prefix="$HOME/.local/" to install a Python in its home directory.

--exec-prefix=EPREFIX

Install architecture-dependent files in EPREFIX, defaults to --prefix.

這個值可以在 runtime 使用 sys.exec_prefix 取得

--disable-test-modules

Don't build nor install test modules, like the test package or the _testcapi extension module (built and installed by default).

在 3.10 版新加入.

--with-ensurepip=[upgrade|install|no]

選擇在 Python 安裝時執行的 ensurepip 命令：

• upgrade （預設）：執行 python -m ensurepip --altinstall --upgrade 命令。

• install：執行 python -m ensurepip --altinstall 命令；

• no：不要執行 ensurepip；

在 3.6 版新加入.

3.3.4. Performance options

Configuring Python using --enable-optimizations --with-lto (PGO + LTO) is recommended for best performance. The experimental --enable-bolt flag can also be used to improve performance.

--enable-optimizations

Enable Profile Guided Optimization (PGO) using PROFILE_TASK (disabled by default).

The C compiler Clang requires llvm-profdata program for PGO. On macOS, GCC also requires it: GCC is just an alias to Clang on macOS.

Disable also semantic interposition in libpython if --enable-shared and GCC is used: add -fno-semantic-interposition to the compiler and linker flags.

在 3.6 版新加入.

在 3.10 版的變更: 在 GCC 上使用 -fno-semantic-interposition。

PROFILE_TASK

Environment variable used in the Makefile: Python command line arguments for the PGO generation task.

預設值：-m test --pgo --timeout=$(TESTTIMEOUT)。

在 3.8 版新加入.

--with-lto=[full|thin|no|yes]

Enable Link Time Optimization (LTO) in any build (disabled by default).

The C compiler Clang requires llvm-ar for LTO (ar on macOS), as well as an LTO-aware linker (ld.gold or lld).

在 3.6 版新加入.

在 3.11 版新加入: To use ThinLTO feature, use --with-lto=thin on Clang.

在 3.12 版的變更: Use ThinLTO as the default optimization policy on Clang if the compiler accepts the flag.

--enable-bolt

Enable usage of the BOLT post-link binary optimizer (disabled by default).

BOLT is part of the LLVM project but is not always included in their binary distributions. This flag requires that llvm-bolt and merge-fdata are available.

BOLT is still a fairly new project so this flag should be considered experimental for now. Because this tool operates on machine code its success is dependent on a combination of the build environment + the other optimization configure args + the CPU architecture, and not all combinations are supported. BOLT versions before LLVM 16 are known to crash BOLT under some scenarios. Use of LLVM 16 or newer for BOLT optimization is strongly encouraged.

The BOLT_INSTRUMENT_FLAGS and BOLT_APPLY_FLAGS configure variables can be defined to override the default set of arguments for llvm-bolt to instrument and apply BOLT data to binaries, respectively.

在 3.12 版新加入.

--with-computed-gotos

Enable computed gotos in evaluation loop (enabled by default on supported compilers).

--without-pymalloc

Disable the specialized Python memory allocator pymalloc (enabled by default).

另請參閱 PYTHONMALLOC 環境變數。

--without-doc-strings

Disable static documentation strings to reduce the memory footprint (enabled by default). Documentation strings defined in Python are not affected.

不要定義 WITH_DOC_STRINGS 巨集。

請見 PyDoc_STRVAR() 巨集。

--enable-profiling

Enable C-level code profiling with gprof (disabled by default).

--with-strict-overflow

Add -fstrict-overflow to the C compiler flags (by default we add -fno-strict-overflow instead).

3.3.5. Python Debug Build

A debug build is Python built with the --with-pydebug configure option.

Effects of a debug build:

• Display all warnings by default: the list of default warning filters is empty in the warnings module.

• 新增 d 到 sys.abiflags。

• 新增 sys.gettotalrefcount() 函式。

• 新增 -X showrefcount 命令列選項。

• Add -d command line option and PYTHONDEBUG environment variable to debug the parser.

• Add support for the __lltrace__ variable: enable low-level tracing in the bytecode evaluation loop if the variable is defined.

• Install debug hooks on memory allocators to detect buffer overflow and other memory errors.

• 定義 Py_DEBUG 和 Py_REF_DEBUG 巨集。

• Add runtime checks: code surrounded by #ifdef Py_DEBUG and #endif. Enable assert(...) and _PyObject_ASSERT(...) assertions: don't set the NDEBUG macro (see also the --with-assertions configure option). Main runtime checks:

  • Add sanity checks on the function arguments.

  • Unicode and int objects are created with their memory filled with a pattern to detect usage of uninitialized objects.

  • Ensure that functions which can clear or replace the current exception are not called with an exception raised.

  • Check that deallocator functions don't change the current exception.

  • The garbage collector (gc.collect() function) runs some basic checks on objects consistency.

  • The Py_SAFE_DOWNCAST() macro checks for integer underflow and overflow when downcasting from wide types to narrow types.

See also the Python Development Mode and the --with-trace-refs configure option.

在 3.8 版的變更: Release builds and debug builds are now ABI compatible: defining the Py_DEBUG macro no longer implies the Py_TRACE_REFS macro (see the --with-trace-refs option), which introduces the only ABI incompatibility.

3.3.6. Debug options

--with-pydebug

Build Python in debug mode: define the Py_DEBUG macro (disabled by default).

--with-trace-refs

Enable tracing references for debugging purpose (disabled by default).

Effects:

• 定義 Py_TRACE_REFS 巨集。

• 新增 sys.getobjects() 函式。

• 新增 PYTHONDUMPREFS 環境變數。

This build is not ABI compatible with release build (default build) or debug build (Py_DEBUG and Py_REF_DEBUG macros).

在 3.8 版新加入.

--with-assertions

Build with C assertions enabled (default is no): assert(...); and _PyObject_ASSERT(...);.

If set, the NDEBUG macro is not defined in the OPT compiler variable.

See also the --with-pydebug option (debug build) which also enables assertions.

在 3.6 版新加入.

--with-valgrind

啟用 Valgrind 支援（預設不啟用）。

--with-dtrace

啟用 DTrace 支援（預設不啟用）。

See Instrumenting CPython with DTrace and SystemTap.

在 3.6 版新加入.

--with-address-sanitizer

Enable AddressSanitizer memory error detector, asan (default is no).

在 3.6 版新加入.

--with-memory-sanitizer

Enable MemorySanitizer allocation error detector, msan (default is no).

在 3.6 版新加入.

--with-undefined-behavior-sanitizer

Enable UndefinedBehaviorSanitizer undefined behaviour detector, ubsan (default is no).

在 3.6 版新加入.

3.3.7. Linker options

--enable-shared

Enable building a shared Python library: libpython (default is no).

--without-static-libpython

Do not build libpythonMAJOR.MINOR.a and do not install python.o (built and enabled by default).

在 3.10 版新加入.

3.3.8. 函式庫選項

--with-libs='lib1 ...'

Link against additional libraries (default is no).

--with-system-expat

Build the pyexpat module using an installed expat library (default is no).

--with-system-libmpdec

Build the _decimal extension module using an installed mpdec library, see the decimal module (default is no).

在 3.3 版新加入.

--with-readline=editline

Use editline library for backend of the readline module.

定義 WITH_EDITLINE 巨集。

在 3.10 版新加入.

--without-readline

Don't build the readline module (built by default).

不要定義 HAVE_LIBREADLINE 巨集。

在 3.10 版新加入.

--with-libm=STRING

Override libm math library to STRING (default is system-dependent).

--with-libc=STRING

Override libc C library to STRING (default is system-dependent).

--with-openssl=DIR

Root of the OpenSSL directory.

在 3.7 版新加入.

--with-openssl-rpath=[no|auto|DIR]

Set runtime library directory (rpath) for OpenSSL libraries:

• no (default): don't set rpath;

• auto: auto-detect rpath from --with-openssl and pkg-config;

• DIR: set an explicit rpath.

在 3.10 版新加入.

3.3.9. Security Options

--with-hash-algorithm=[fnv|siphash13|siphash24]

Select hash algorithm for use in Python/pyhash.c:

• siphash13 (default);

• siphash24；

• fnv。

在 3.4 版新加入.

在 3.11 版新加入: siphash13 is added and it is the new default.

--with-builtin-hashlib-hashes=md5,sha1,sha256,sha512,sha3,blake2

內建雜湊模組：

• md5；

• sha1；

• sha256；

• sha512；

• sha3 (with shake);

• blake2。

在 3.9 版新加入.

--with-ssl-default-suites=[python|openssl|STRING]

Override the OpenSSL default cipher suites string:

• python (default): use Python's preferred selection;

• openssl: leave OpenSSL's defaults untouched;

• STRING: use a custom string

請見 ssl 模組。

在 3.7 版新加入.

在 3.10 版的變更: The settings python and STRING also set TLS 1.2 as minimum protocol version.

3.3.10. macOS 選項

參閱 Mac/README.rst。

--enable-universalsdk

--enable-universalsdk=SDKDIR

Create a universal binary build. SDKDIR specifies which macOS SDK should be used to perform the build (default is no).

--enable-framework

--enable-framework=INSTALLDIR

Create a Python.framework rather than a traditional Unix install. Optional INSTALLDIR specifies the installation path (default is no).

--with-universal-archs=ARCH

Specify the kind of universal binary that should be created. This option is only valid when --enable-universalsdk is set.

選項：

• universal2；

• 32-bit；

• 64-bit；

• 3-way；

• intel；

• intel-32；

• intel-64；

• all。

--with-framework-name=FRAMEWORK

Specify the name for the python framework on macOS only valid when --enable-framework is set (default: Python).

3.3.11. Cross Compiling Options

Cross compiling, also known as cross building, can be used to build Python for another CPU architecture or platform. Cross compiling requires a Python interpreter for the build platform. The version of the build Python must match the version of the cross compiled host Python.

--build=BUILD

configure for building on BUILD, usually guessed by config.guess.

--host=HOST

cross-compile to build programs to run on HOST (target platform)

--with-build-python=path/to/python

path to build python binary for cross compiling

在 3.11 版新加入.

CONFIG_SITE=file

An environment variable that points to a file with configure overrides.

Example config.site file:

# config.site-aarch64
ac_cv_buggy_getaddrinfo=no
ac_cv_file__dev_ptmx=yes
ac_cv_file__dev_ptc=no

Cross compiling example:

CONFIG_SITE=config.site-aarch64 ../configure \
    --build=x86_64-pc-linux-gnu \
    --host=aarch64-unknown-linux-gnu \
    --with-build-python=../x86_64/python

3.4. Python Build System

3.4.1. Main files of the build system

• configure.ac => configure；

• Makefile.pre.in => Makefile (created by configure);

• pyconfig.h (created by configure)；

• Modules/Setup: C extensions built by the Makefile using Module/makesetup shell script;

3.4.2. 主要建置步驟

• C files (.c) are built as object files (.o).

• A static libpython library (.a) is created from objects files.

• python.o and the static libpython library are linked into the final python program.

• C extensions are built by the Makefile (see Modules/Setup).

3.4.3. 主要 Makefile 目標

• make: Build Python with the standard library.

• make platform:: build the python program, but don't build the standard library extension modules.

• make profile-opt: build Python using Profile Guided Optimization (PGO). You can use the configure --enable-optimizations option to make this the default target of the make command (make all or just make).

• make buildbottest: Build Python and run the Python test suite, the same way than buildbots test Python. Set TESTTIMEOUT variable (in seconds) to change the test timeout (1200 by default: 20 minutes).

• make install: Build and install Python.

• make regen-all: Regenerate (almost) all generated files; make regen-stdlib-module-names and autoconf must be run separately for the remaining generated files.

• make clean: Remove built files.

• make distclean: Same than make clean, but remove also files created by the configure script.

3.4.4. C 擴充模組

Some C extensions are built as built-in modules, like the sys module. They are built with the Py_BUILD_CORE_BUILTIN macro defined. Built-in modules have no __file__ attribute:

>>> import sys
>>> sys
<module 'sys' (built-in)>
>>> sys.__file__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'sys' has no attribute '__file__'

Other C extensions are built as dynamic libraries, like the _asyncio module. They are built with the Py_BUILD_CORE_MODULE macro defined. Example on Linux x86-64:

>>> import _asyncio
>>> _asyncio
<module '_asyncio' from '/usr/lib64/python3.9/lib-dynload/_asyncio.cpython-39-x86_64-linux-gnu.so'>
>>> _asyncio.__file__
'/usr/lib64/python3.9/lib-dynload/_asyncio.cpython-39-x86_64-linux-gnu.so'

Modules/Setup is used to generate Makefile targets to build C extensions. At the beginning of the files, C extensions are built as built-in modules. Extensions defined after the *shared* marker are built as dynamic libraries.

The PyAPI_FUNC(), PyAPI_DATA() and PyMODINIT_FUNC macros of Include/exports.h are defined differently depending if the Py_BUILD_CORE_MODULE macro is defined:

• 如果定義了 Py_BUILD_CORE_MODULE，則使用 Py_EXPORTED_SYMBOL

• 否則使用 Py_IMPORTED_SYMBOL。

If the Py_BUILD_CORE_BUILTIN macro is used by mistake on a C extension built as a shared library, its PyInit_xxx() function is not exported, causing an ImportError on import.

3.5. Compiler and linker flags

Options set by the ./configure script and environment variables and used by Makefile.

3.5.1. Preprocessor flags

CONFIGURE_CPPFLAGS

Value of CPPFLAGS variable passed to the ./configure script.

在 3.6 版新加入.

CPPFLAGS

(Objective) C/C++ preprocessor flags, e.g. -Iinclude_dir if you have headers in a nonstandard directory include_dir.

Both CPPFLAGS and LDFLAGS need to contain the shell's value to be able to build extension modules using the directories specified in the environment variables.

BASECPPFLAGS

在 3.4 版新加入.

PY_CPPFLAGS

Extra preprocessor flags added for building the interpreter object files.

Default: $(BASECPPFLAGS) -I. -I$(srcdir)/Include $(CONFIGURE_CPPFLAGS) $(CPPFLAGS).

在 3.2 版新加入.

3.5.2. 編譯器旗標

CC

C 編譯器指令。

Example: gcc -pthread.

CXX

C++ 編譯器指令。

範例：g++ -pthread。

CFLAGS

C 編譯器旗標。

CFLAGS_NODIST

CFLAGS_NODIST is used for building the interpreter and stdlib C extensions. Use it when a compiler flag should not be part of CFLAGS once Python is installed (gh-65320).

In particular, CFLAGS should not contain:

• the compiler flag -I (for setting the search path for include files). The -I flags are processed from left to right, and any flags in CFLAGS would take precedence over user- and package-supplied -I flags.

• hardening flags such as -Werror because distributions cannot control whether packages installed by users conform to such heightened standards.

在 3.5 版新加入.

COMPILEALL_OPTS

Options passed to the compileall command line when building PYC files in make install. Default: -j0.

在 3.12 版新加入.

EXTRA_CFLAGS

額外的 C 編譯器旗標。

CONFIGURE_CFLAGS

Value of CFLAGS variable passed to the ./configure script.

在 3.2 版新加入.

CONFIGURE_CFLAGS_NODIST

Value of CFLAGS_NODIST variable passed to the ./configure script.

在 3.5 版新加入.

BASECFLAGS

基本編譯器旗標。

OPT

最佳化旗標。

CFLAGS_ALIASING

Strict or non-strict aliasing flags used to compile Python/dtoa.c.

在 3.7 版新加入.

CCSHARED

Compiler flags used to build a shared library.

例如說 -fPIC 被使用於 Linux 與 BSD 上。

CFLAGSFORSHARED

Extra C flags added for building the interpreter object files.

Default: $(CCSHARED) when --enable-shared is used, or an empty string otherwise.

PY_CFLAGS

Default: $(BASECFLAGS) $(OPT) $(CONFIGURE_CFLAGS) $(CFLAGS) $(EXTRA_CFLAGS).

PY_CFLAGS_NODIST

Default: $(CONFIGURE_CFLAGS_NODIST) $(CFLAGS_NODIST) -I$(srcdir)/Include/internal.

在 3.5 版新加入.

PY_STDMODULE_CFLAGS

C flags used for building the interpreter object files.

Default: $(PY_CFLAGS) $(PY_CFLAGS_NODIST) $(PY_CPPFLAGS) $(CFLAGSFORSHARED).

在 3.7 版新加入.

PY_CORE_CFLAGS

Default: $(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE.

在 3.2 版新加入.

PY_BUILTIN_MODULE_CFLAGS

Compiler flags to build a standard library extension module as a built-in module, like the posix module.

Default: $(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE_BUILTIN.

在 3.8 版新加入.

PURIFY

Purify command. Purify is a memory debugger program.

Default: empty string (not used).

3.5.3. Linker flags

LINKCC

Linker command used to build programs like python and _testembed.

Default: $(PURIFY) $(CC).

CONFIGURE_LDFLAGS

Value of LDFLAGS variable passed to the ./configure script.

Avoid assigning CFLAGS, LDFLAGS, etc. so users can use them on the command line to append to these values without stomping the pre-set values.

在 3.2 版新加入.

LDFLAGS_NODIST

LDFLAGS_NODIST is used in the same manner as CFLAGS_NODIST. Use it when a linker flag should not be part of LDFLAGS once Python is installed (gh-65320).

In particular, LDFLAGS should not contain:

• the compiler flag -L (for setting the search path for libraries). The -L flags are processed from left to right, and any flags in LDFLAGS would take precedence over user- and package-supplied -L flags.

CONFIGURE_LDFLAGS_NODIST

Value of LDFLAGS_NODIST variable passed to the ./configure script.

在 3.8 版新加入.

LDFLAGS

Linker flags, e.g. -Llib_dir if you have libraries in a nonstandard directory lib_dir.

Both CPPFLAGS and LDFLAGS need to contain the shell's value to be able to build extension modules using the directories specified in the environment variables.

LIBS

Linker flags to pass libraries to the linker when linking the Python executable.

範例：-lrt。

LDSHARED

Command to build a shared library.

預設值：@LDSHARED@ $(PY_LDFLAGS)。

BLDSHARED

Command to build libpython shared library.

預設值：@BLDSHARED@ $(PY_CORE_LDFLAGS)。

PY_LDFLAGS

預設值：$(CONFIGURE_LDFLAGS) $(LDFLAGS)。

PY_LDFLAGS_NODIST

預設值：$(CONFIGURE_LDFLAGS_NODIST) $(LDFLAGS_NODIST)。

在 3.8 版新加入.

PY_CORE_LDFLAGS

Linker flags used for building the interpreter object files.

在 3.8 版新加入.