Python's Experimental JIT Compiler to be Removed from CPython 3.13

Experimental JIT Removal

The experimental Just-In-Time (JIT) compiler, which was integrated into CPython for the upcoming 3.13 release, is slated for removal. This decision follows a period of discussion and a formal request from the Python steering council regarding the JIT's future.

Steering Council's Concerns

In June, the Python steering council paused work on the JIT in CPython's main branch. They mandated an accepted Python Enhancement Proposal (PEP) to address concerns about maintenance, compatibility, and to establish clear success metrics and a timeline for completion. This request aimed to ensure the JIT's development did not interfere with other projects, including instrumentation, debugging, and profiling.

PEP Withdrawal

In response to the council's request, the JIT maintainers drafted PEP 836 ("JIT Go Brrr: The Path to a Supported JIT Compiler for CPython"). However, after months of discussion, the maintainers withdrew the PEP. This withdrawal signifies the end of development for this specific JIT project within CPython for the foreseeable future.

Background of JIT Integration

The JIT was initially added to CPython by Brandt Bucher in early 2024. Typically, major features require a standards-track PEP approval from the council before integration. Bucher and Savannah Ostrowski had previously drafted PEP 744 ("JIT Compilation"), which was an informational PEP and did not represent formal consensus for proceeding with the feature.