>> While the intent is not to call for competing proposals, we believe that now is a good time to discuss and propose alternative proposals as well.

lol

>> For example, rather than proposing one single concrete JIT implementation, it may make more sense for the PEP to describe a JIT infrastructure that can support multiple implementation strategies.

poison-pill requirement

>> We are setting a window of six months for a PEP to be submitted and resolved. If no such PEP is accepted within that window, the JIT code must be removed from the main branch

so it's going to be removed from the main branch

> For that reason, the Steering Council is formally requesting a Standards Track PEP be authored that the community can discuss and the Steering Council can formally accept (or reject), making the case for the JIT as a supported, non-experimental part of CPython: its guarantees, its maintenance commitments, and its impact on redistributors.

I didn't notice the current PEP was a provisional one. Hope the new one gets approved. The experimental JIT was reported to finally breaking even and surpassing the default interpreter just a couple of months ago[1].

[1] https://fidget-spinner.github.io/posts/jit-on-track.html

>The experimental JIT was reported to finally breaking even and surpassing the default interpreter just a couple of months ago[1].

Thank You. As someone who don't follow python closely I thought their JIT would be similar to what Ruby has.

Not that Ruby YJIT or ZJIT is anywhere close to what JVM provides, but in this case it seems to be quite far ahead of Python.

Which is surprising given how many major companies are using Python. May be because those using Python are not using it as critical part of work unlike Shopify and Stripe which is their core language?

Python software is to a large extent either doing things in not-python (c, c++, rust, etc.) or doing things that are not cpu bound (io bound, async, etc.). If you're cpu bound then you can either take a 2x jit improvement or take a 10x non-python improvement. There's few companies of a scale where the non-hot path cost of 2x cpu is so massive as to be worth caring about.

Sure but best case 15% faster clearly isn't worth the complexity of a JIT. It really needs to be at least twice as fast. Pypy pretty much achieves that on average.

15% faster on top of a base interpreter that itself got 40%-50% faster on the same timeframe.

The post clearly says the intention is to get a formal spec for formal integration.

To leave their experimental phase they have to define some goals to meet and that requires making some architectural choices that still aren't decided.

I suspect the recent "we updated the GC without a PEP and it went live and caused massive issues and we need an emergency point release revert" pushed for a greater degree of process overall.

Sounds reasonable given the recent YOLO GC debacle https://discuss.python.org/t/reverting-the-incremental-gc-in....

What a shame it will receive a halt when they where starting to make progress I know that after submitting the pep it will go back to development. But t would have been better to just keep the development and the pep for an actual release or continue and if gets rejected ask them to stop

> What a shame it will receive a halt when they where starting to make progress I know that after submitting the pep it will go back to development.

To be fair, the apparent lack of progress of the JIT before was in part due to the same team improving the base interpreter by 40-50% between 3.10 and 3.14. The JIT implementation was pursuing a moving target. It was not some static milestone. Kudos for them.

That was kind of overdue. The project started five years ago while massively overpromising.

They should perhaps have kept it in a separate branch back then, but now is the next best time.

CPython's selling point was that it is simple, fast enough with C extensions and the code was accessible. Complicating the code base for occasional 50% speedups (and regressions ...) just isn't worth it. There are so many other languages that fill that need.

Now, I hope that the PEP does not overpromise again and is accepted because of Instagram pressure. Instagram can keep its own JIT fork or switch to PHP, Go or whatever.

"Asked to pause development" isn't entirely accurate: they were asked to pause landing new features (as opposed to bug fixes) on the cPython main branch.

Losing development momentum for a beancounting reason like this one is a sure way to kill a project. It works every time. Once development is halted, it is very difficult to pick it back up.

Python isn't a side project to yolo on. Updating the GC without a PEP caused massive issues for actual people using Python. If you want to impact software used by millions of developers then you better be willing to handle a bit of process.

They're not being asked to halt development, they're being asked to halt landing new features on the cPython main branch.

The JIT project already lost a lot of momentum when the people working on it lost their jobs (at Microsoft)..

I agree. And the next section is very clear that they want to kill the project.

  > For example, rather than proposing one single concrete JIT implementation,
  > it may make more sense for the PEP to describe a JIT infrastructure that
  > can support multiple implementation strategies.
  > Since many different and promising JIT tracing approaches continue to be proposed,
  > we believe the infrastructure should make it easy to experiment with and evaluate
  > those approaches within CPython rather than be highly coupled with a single strategy.

Allowing multiple strategies is far harder and as far as I know, JIT tracing is still unproven.

I think this is uncharitable, it's not like they're inventing new requirements that weren't there before. The PEP process has existed the whole time.

I suspect there were people who had alternative proposals which got implicitly blocked by this 5 year effort. Letting a subgroup run wild without proper process is not good for a project this large.