GIL in Python 3.13 – what you need to know?

Python is one of the most popular programming languages. Let’s be honest – I’m not surprised at all. Python is simple, super cool and great even for programmers who are new to programming. I programmed in Python and Java, and honestly – python is always number one for me. Today I will focus on one of the interesting Python things – GIL.

What is GIL?

GIL (Global Interpreter Lock) is a mechanism in Python that ensures that only one thread can execute Python bytecode at a time. This lock is needed for memory management in the CPython implementation (the most common Python implementation).

When Python code is executing, the GIL allows only one thread to hold a lock on the interpreter at a time. This means that even if you have multiple threads within a single Python process, only one of them can be active at the same time, which can lead to inefficient use of multi-core processors.

Why is GIL problematic?

The GIL can be particularly problematic in the context of multi-threaded processing:

• Performance limitation: Thanks to the GIL, Python cannot use all the cores of multi-core processors for multi-threaded processing, which means that some applications will not run faster even on more powerful hardware.
• Resource control: For applications that require intensive calculations or work with large amounts of data, the GIL limits the ability to efficiently distribute tasks among threads, which can lead to situations where one thread takes up most of the CPU time while others wait.
• I/O Performance: While the GIL is not a major problem for I/O-oriented applications (such as network communication), it still presents a bottleneck for I/O-heavy applications if those applications try to at the same time perform computationally intensive operations.

When will Python 3.13 be released?

Python 3.13 is planned for release sometime in 2025, with alpha versions available as early as 2024. Python development follows a regular cycle, with major versions released every 1.5 years. This cycle gives communities and developers enough time to test and adapt their code for new releases.

What happens to the GIL in Python 3.13?

In Python 3.13, the GIL will not be removed completely, but it is planned to be optional. This means that developers will be able to decide whether their applications will use the GIL or not. This change will allow existing applications that depend on the GIL to run smoothly, while new applications or those that need full-fledged multi-threading will be able to turn off the GIL to gain more performance.

This approach to an optional GIL provides a compromise between maintaining compatibility with legacy code and enabling advanced multithreading for applications that require it. This opens up the possibility for Python developers to gradually adapt and optimize their code without the need for immediate major changes in existing applications.