Build Python with GIL Disabled on CentOS 8

Notes:

• This is for fun only, shouldn’t apply to production
  • Lots of stuff may not be present during compiling Python from source, programmes run on the resulting Python compilation may break
  • Author may not maintain the no-GIL repo for long.

The design of Python on CPython is crazy with the GIL (Global Interpreter Lock). This GIL make the ‘threading’ module of Python all fake, it doesn’t do multithreading at all, just only 1 thread running at a time, swapping around just as async IO.

There’s a project here which is a fork of the original python/cpython project with altered source code to disabled GIL by default:

https://github.com/colesbury/nogil

Clone the source code:

git clone https://github.com/colesbury/nogil.git python-nogil

Install required modules before compiling Python (on CentOS 8 for example):
sudo dnf install -y gcc gcc-c++ gfortran openblas

• gfortran openblas are for Scipy

sudo dnf install -y zlib-devel openssl-devel libffi-devel openblas-devel lapack-devel

• zlib-devel is required for Python build
• openssl-devel is for Pip
• libffi-devel is for multiple modules installed by Pip
• openblas-devel lapack-devel are for Scipy

Compile and install Python No-GIL (currently 3.9 in Oct 2021), this takes a while, rather quick, maybe a quarter:

cd python-nogil
./configure
make -j
sudo make install # We have /usr/local/bin/python3 after this.