Python's experimental just-in-time (JIT) compiler, introduced in CPython 3.13 in 2024, is being removed from the main development branch. The Python steering council paused JIT work in June, demanding a standards-track Python Enhancement Proposal (PEP) to address maintenance, compatibility, and success metrics. Despite months of discussion and the drafting of PEP 836, titled "JIT Go Brrr: The Path to a Supported JIT Compiler for CPython," the JIT maintainers have withdrawn the proposal. The council set a six-month deadline for a formal PEP to justify the JIT as a supported, non-experimental feature, including guarantees, maintenance commitments, and impact on redistributors. With the deadline passed and the PEP withdrawn, development on the project appears to have ended.
The JIT was added by Brandt Bucher in early 2024 without the usual council-approved PEP, initially relying on an informational PEP 744. The council later intervened, citing concerns over instrumentation, debugging, profiling, and external JITs like Cinder X and Numba. Community feedback on PEP 836 was mixed, with many calling for it to be split into two separate PEPs—one for goals and one for implementation details. Bucher and co-authors Savannah Ostrowski and Ken Jin defended the structure, but ultimately withdrew the proposal. For now, the JIT's future in CPython remains uncertain.
Source: Hacker News · Summarized by HeadlinesBriefing