Running with the GIL disabled
Info
Most of the content on this page is also covered in the Python 3.13 release notes.
Note
The free-threaded Python executable will always have a python3.13t
alias
(for Python 3.13); whether python
, python3
and/or python3.13
point at
the free-threaded executable or not will depend on the installation method
(see the install guide for more details).
For example, the Python 3.13 Windows installer from python.org
installs the free-threaded binary as python3.13t.exe
(with a "t" suffix
to indicate it is "t"hreaded), whereas the standard GIL-enabled Python
binary is simply named python.exe
(as usual). If you cannot find the
free-threaded binary, that means the free-threaded option was not selected
during installation.
You can verify your build of CPython itself has the GIL disabled with the following incantation:
python -VV
If you are using Python 3.13b1 or newer, you should see a message like:
Python 3.13.0b1+ experimental free-threading build (heads/3.13:d93c4f9, May 21 2024, 10:54:14) [Clang 15.0.0 (clang-1500.1.0.2.5)]
Verify that the GIL is disabled at runtime with the following incantation:
python -c "import sys; print(sys._is_gil_enabled())"
To force Python to keep the GIL disabled even after importing a module
that does not support running without it, use the PYTHON_GIL
environment
variable or the -X gil
command line option:
# these are equivalent
PYTHON_GIL=0 python
python -Xgil=0