Kleckner: Unladen Swallow Retrospective

Posted Mar 28, 2011 10:41 UTC (Mon) by pboddie (subscriber, #50784) [Link]

PyPy is really coming into its own now, given that the JIT architecture seems to have settled down. I think there was a lot of skepticism from the direction of PyPy about whether Unladen Swallow could realistically deliver on a strategy which seemed to have a fair amount in common with Psyco (which is pretty much the forerunner of PyPy), and as the article mentions, when LLVM failed to provide the anticipated help in doing the tricky code generation parts, the effort required to tame LLVM in addition to doing all the other work probably weighed the project down a bit too much.

None of this indicates that you can't improve CPython's performance or build on CPython and get improved performance for, say, compiled (or "frozen", in Python-speak) programs. There are implementations which seem to have achieved these goals, albeit not at the order of magnitude level of performance improvement that one might like to see.

Personally, I think the remarks made in the Hacker News thread cross over with the observations about "turn-key" compatibility in the article and highlight a sticking point when it comes to improving Python's performance: lots of people won't even consider anything less than 100% compatibility with CPython with all the crazy hacks that it allows, making the optimisation work a lot harder than it otherwise might be. So people have traditionally turned their noses up at things which offer significant performance increases, and there's no debate about which parts of the language could usefully be jettisoned to provide such benefits more conveniently. If anything, people are still discussing yet more stuff to put in the language, not which stuff should arguably go away (or at least take a back seat).