3 ms·

Hm yes I was wrong about that. It looks like v8 and PyPy do it (which is apparent from some Googling and grepping of the code). I have been reading some paper

by chubot 8y ago

Hm yes I was wrong about that. It looks like v8 and PyPy do it (which is apparent from some Googling and grepping of the code). I have been reading some papers on JITs and I don't see escape analysis mentioned that often. In the PyPy paper (which is over a decade old) they mention it as future work. Still, I actually tried PyPy on a string-based workload and it was slower than CPython and used more memory. I don't know why but that contributes to my feeling that JITs are bad for string-based workloads. I'm interested in seeing any pointers to benchmarks that show the improvements resulting from escape analysis in JITs. I haven't seen anything like that and I've done a decent amount of research. A cursory look at this blog post makes me think it's not super straightforward: https://v8project.blogspot.com/2017/09/disabling-escape-analysis.html https://v8project.blogspot.com/2017/09/disabling-escape-anal... That post is less than a year old! i.e. the fact that v8 has been around for 10+ years and they're still updating escape analysis makes me wonder what the issue with it is. Is it hard to implement or does it not produce that much speedup? I appreciate any pointers.

chrisseaton 8y ago
> I'm interested in seeing any pointers to benchmarks that show the improvements resulting from escape analysis in JITs. I haven't seen anything like that and I've done a decent amount of research. If you've done a decent amount of research in the field of JITs and you aren't aware of what escape analysis achieves in practice then I'm very surprised. http://www.ssw.uni-linz.ac.at/Research/Papers/Stadler14/Stadler2014-CGO-PEA.pdf http://www.ssw.uni-linz.ac.at/Research/Papers/Stadler14/Stad... That paper is relatively recent, so you can follow the chain of papers from its references.
mamcx 8y ago
>Still, I actually tried PyPy on a string-based workload and it was slower than CPython and used more memory. I don't know why but that contributes to my feeling that JITs are bad for string-based workloads. Now that I'm implementing a interpreter for a relational language and from what I know for why python is slow: https://jakevdp.github.io/blog/2014/05/09/why-python-is-slow/ https://jakevdp.github.io/blog/2014/05/09/why-python-is-slow... And also: https://speakerdeck.com/alex/why-python-ruby-and-javascript-are-slow https://speakerdeck.com/alex/why-python-ruby-and-javascript-... Is challenging to be dynamic and also fast. So, you need to design the language/runtime with performance in mind, or at least, to minimize what could be very slow (that is what I'm triying).

by chubot 8y ago

chrisseaton 8y ago

> I'm interested in seeing any pointers to benchmarks that show the improvements resulting from escape analysis in JITs. I haven't seen anything like that and I've done a decent amount of research. If you've done a decent amount of research in the field of JITs and you aren't aware of what escape analysis achieves in practice then I'm very surprised. http://www.ssw.uni-linz.ac.at/Research/Papers/Stadler14/Stadler2014-CGO-PEA.pdf http://www.ssw.uni-linz.ac.at/Research/Papers/Stadler14/Stad... That paper is relatively recent, so you can follow the chain of papers from its references.

mamcx 8y ago

>Still, I actually tried PyPy on a string-based workload and it was slower than CPython and used more memory. I don't know why but that contributes to my feeling that JITs are bad for string-based workloads. Now that I'm implementing a interpreter for a relational language and from what I know for why python is slow: https://jakevdp.github.io/blog/2014/05/09/why-python-is-slow/ https://jakevdp.github.io/blog/2014/05/09/why-python-is-slow... And also: https://speakerdeck.com/alex/why-python-ruby-and-javascript-are-slow https://speakerdeck.com/alex/why-python-ruby-and-javascript-... Is challenging to be dynamic and also fast. So, you need to design the language/runtime with performance in mind, or at least, to minimize what could be very slow (that is what I'm triying).