gh-116167: Allow disabling the GIL (github.com)

Article summary

A new feature has been added to Python that allows disabling the Global Interpreter Lock (GIL) using the PYTHON_GIL=0 environment variable or the -X gil=0 command line option. This feature is currently only available in free-threaded builds and is intended as a first step towards making the GIL optional. Disabling the GIL can potentially unlock true multi-core parallelism for multi-threaded programs, but it also breaks some tests, including asyncio tests. The feature is still in development and may change in the future.

Main themes

• Python GIL
• Multi-threading
• Parallelism
• Performance optimization
• Concurrency

What commenters say

• Disabling the GIL can potentially improve performance for multi-threaded programs, but it requires careful consideration of thread safety and concurrency issues.
• The current implementation of GIL disabling breaks some tests, including asyncio tests, and is not yet suitable for production use.
• Some commenters argue that the problems with the GIL are overstated and that existing solutions, such as the multiprocessing module, can provide efficient parallelism for many use cases.
• Others believe that disabling the GIL is a significant step forward for Python and will enable new use cases and performance improvements, but it will require changes to existing code and careful testing.
• There is disagreement about the potential performance impact of disabling the GIL, with some arguing that it will improve performance and others claiming that it will introduce new overhead and potentially slow down single-threaded programs.
• The implementation of GIL disabling is seen as a complex task that requires careful consideration of trade-offs between performance, safety, and compatibility.