TL;DR
The Python Steering Council has asked to halt all new development on the experimental JIT compiler in CPython until a formal Standards Track PEP is approved. Bug fixes may continue, but no new features or optimizations are allowed during this period. The move aims to bring clarity and formal support to the project.
The Python Steering Council has officially requested a pause on all new development related to the experimental JIT compiler in CPython, pending the submission and approval of a formal Standards Track PEP. This decision aims to bring clarity and formal support to the project amid ongoing discussions about its long-term maintenance and integration.
Over the past several years, core developers and contributors have been working on integrating a JIT compiler into CPython’s main branch as an experimental feature. Despite encouraging performance improvements, the project has undergone multiple re-architectures, and its formal status remains undefined. The Steering Council’s recent directive is to halt all new features, optimizations, and performance work on the JIT until a community-driven PEP is submitted and accepted.
The PEP is expected to define the long-term maintenance, compatibility guarantees, and the scope of the JIT’s support within CPython. It will also clarify how the JIT interacts with existing features such as debugging, profiling, and multi-threading. The council emphasizes that bug fixes and security patches may continue during this period, but no new JIT functionalities should be added.
Why It Matters
This move is significant because it formalizes the status of the JIT project within CPython, ensuring that future development aligns with community consensus and clear support commitments. It also prevents uncoordinated changes that could complicate the project’s integration and long-term stability. For users and downstream developers, this decision aims to provide greater clarity about the project’s future and the conditions under which the JIT might become a supported feature.
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Background
The JIT project was initially merged into CPython as an experimental feature, with the only formal documentation being PEP 744, which outlined the initial design and open questions. Over time, various proposals and re-architectures have been discussed, but no formal process has yet been followed to establish it as a supported, long-term feature. The current pause reflects a recognition that formal governance and clear commitments are necessary before further development continues.
“The Steering Council’s decision to pause JIT development until a PEP is approved is a prudent step to ensure proper process and long-term support.”
— An anonymous researcher on Hacker News
“We want to bring clarity and formal support to the JIT project by requiring a community-approved PEP before further development.”
— Python Steering Council
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What Remains Unclear
It is not yet clear when the PEP will be submitted or approved, or what specific long-term support and guarantees it will include. The future architecture and integration details of the JIT remain under discussion, and the timeline for resuming development is uncertain.
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What’s Next
The community is expected to draft and submit a Standards Track PEP within six months. Once the PEP is reviewed and either accepted or rejected by the Steering Council, further development on the JIT will either proceed under the new formal support framework or be definitively halted. During this period, discussions on alternative proposals and infrastructure improvements are encouraged.
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Key Questions
Why did the Python Steering Council ask to pause JIT development?
The Council wants to ensure that the JIT project follows a formal process, with a community-approved PEP defining its long-term support, maintenance, and integration. This step aims to bring clarity and stability before further development continues.
Can bug fixes and security updates still be made to the JIT?
Yes, bug fixes and security patches may continue as normal during the pause. The restriction applies specifically to new features, optimizations, or performance improvements.
What happens if the PEP is not approved within six months?
If no PEP is accepted within six months, the JIT code must be removed from the main branch of CPython, and further development will need to occur outside the main repository.
Will the JIT project be abandoned entirely?
Not necessarily. The pause is intended to formalize support and ensure proper governance. If the PEP is approved, the project can continue with clear commitments; otherwise, it may be discontinued in the main branch.
Source: Hacker News
