Python -VV should display whether the build is default build or free-threading.

[corona10]

Currently, there is no way to identify whether the build is free-threaded or not through python -VV
See the pyperf and pyperformance case

• no-issue: Update CI to support free-threading psf/pyperf#189
• no-issue: Improve CI for free-threading pyperformance#336

The following display would be great.

Python 3.14.0a0 (heads/main-dirty:31a28cbae0, May 17 2024, 17:30:32, default) [GCC 14.1.1 20240507 (Red Hat 14.1.1-1)]

Python 3.14.0a0 (heads/main-dirty:31a28cbae0, May 17 2024, 17:30:32, free-threading) [GCC 14.1.1 20240507 (Red Hat 14.1.1-1)]

Linked PRs

• gh-119132: Update sys.version to identify free-threaded or not. #119134
• gh-119132: Log sys._is_gil_disabled() in test.pythoninfo #119140
• [3.13] gh-119132: Log sys._is_gil_enabled() in test.pythoninfo (GH-119140) #119143
• gh-119132: Display free-threading information through -VV #119145
• [3.13] gh-119132: Update sys.version to identify free-threaded or not. (gh-119134) #119153
• gh-119132: Remove "experimental" tag from the CPython free-threading. #135550
• [3.14] gh-119132: Remove "experimental" tag from the CPython free-threading. (gh-135550) #135565
• gh-119132: Update 'Using Python on macOS' documentation. #135591
• [3.14] gh-119132: Update 'Using Python on macOS' documentation. (GH-135591) #135594

[corona10]

cc @hugovk @vstinner @colesbury

[vstinner]

If we cannot agree on changing sys.version, at least, python -VV can be modified in Python/initconfig.c:

    if (print_version) {
        printf("Python %s\n",
                (print_version >= 2) ? Py_GetVersion() : PY_VERSION);
        return _PyStatus_EXIT(0);
    }

The code can be modified to log if Python is built with free-threading or not.

[corona10]

If we cannot agree on changing sys.version, at least, python -VV can be modified in Python/initconfig.c:

It's better!