> Adding a freaking JIT to CPython is a ridiculous suggestion that will never happen for a whole load of reasons.
That's a bold statement. Can you elaborate on what those reasons are?
That's a bold statement. Can you elaborate on what those reasons are?
1. The Python language itself doesn't lend itself to being JIT compiled - it's too dynamic.
2. cPython is the reference implementation. It's source should be as simple as possible.
3. Only a subset of Python programs would benefit, and the rest would be slower/more memory hungry
and finally,
4. If you want/need a JIT then use PyPy, in all it's glory with all its upsides and downsides.
PyPy is a big project with a lot of very very very smart people working on it. They've done an excellent job at JITting Python (and creating an impressive interpreter framework) but even they couldn't make a JIT that is anywhere near suitable for inclusion in cPython. A bunch of cPython hackers on python-dev have no chance.
tldr: Want a JIT? Use PyPy.
1. This was also said about JS before people just went ahead and wrote JITs for it. Are you sure what they're saying isn't "we can't make a JIT for python" rather than "nobody can make one"? Because that's how it turned out with JS.
2. If given the choice, do you think the community would turn down a JIT to avoid making the reference implementation more complex? To whose benefit is that requirement? I've never heard people complain about other languages that they didn't have an easy-to-read reference implementation.
3. I've not heard this reported as a problem in practice for languages that have a JIT. It's usually toy programs where the JIT overhead is significant and they're so small and short-running that neither slowdown or extra memory is usually an issue.
4. Not everything that runs on cPython runs on PyPy so that's not a choice I'm necessarily able to make.
I'm not saying there aren't reasons to not have a JIT in cPython. But it's a choice not a natural law. And it's not ridiculous to suggest that they could make a different choice if they wanted, as JS eventually did.
2. It would make the reference implementation insanely more complex, to the point where it is no longer a reference implementation but a JIT implementation of Python. That's not cPython's role. For whos benefit is the requirement of a JIT? My apps run fine without them, and I don't need the memory bloat or startup cost associated with a JIT. If the community really wants another JIT they could fork cPython, find a room full of JIT experts and re-do all of the work PyPy has done, with all of the tradeoffs and problems they encountered. Nice idea.
3. "so small and short-running that neither slowdown or extra memory is usually an issue." - this is exactly the situation where a JIT adds a lot of overhead and becomes an issue.
4. So you want the best of both worlds, with no clear idea as to what magical person can make this happen (or even how) and you won't be happy until you can have your cake and eat it?
It's not that the Python developers preventing discussion, it's just this discussion is always fruitless, has been had many times before and the people invoking the discussion often blame the cPython developers for their response. Nobody wins, it's a waste of time.
Remove the "maintaining compatibility for C-based extensions" requirement, and you get, well, PyPy. And you also get a community split that makes 2/3 look trivial. Vast swathes of core Python code and libraries are really not "Python", but Python C-based bindings to custom code or C libraries.
or spend some time helping with Pyjion to add a C API to CPython for plugging in a JIT of your choice