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Hi HN! I'm Clark, one of the maintainers of magic-trace. magic-trace was submitted before, our first announcement was this blog post: https://blog.janestreet.c

Hi HN! I'm Clark, one of the maintainers of magic-trace. magic-trace was submitted before, our first announcement was this blog post: https://blog.janestreet.com/magic-trace/ https://blog.janestreet.com/magic-trace/. Since then, we've worked hard at making magic-trace more accessible to outside users. We've heard stories of people thinking this was cool before but being unable to even find a download link. I'm posting this here because we just released "version 1.0", which is the first version that we think is sufficiently user-friendly for it to be worth your time to experiment with. And uhh... sorry in advance if you run into hiccups despite our best efforts. Going from dozens of internal users to anyone and everyone is bound to discover new corners we haven't considered yet. Let us know if you run into trouble!

panosfilianos 4y ago
Thanks for sharing this.
giovannibonetti 4y ago
I'm curious about why Standard ML (SML) was chosen for this project, given the track record Jane Street has with OCaml. Do you seen an advantage for using the former in this kind of project?
- tbr1 4y ago
  It's all OCaml, GitHub is just misclassifying it as SML :)
  - mananaysiempre 4y ago
    Hint[1] in case you’re ever in this situation: echo '*.ml linguist-language=OCaml' >> .gitattributes echo '*.mli linguist-language=OCaml' >> .gitattributes [1] https://github.com/github/linguist/blob/master/docs/overrides.md https://github.com/github/linguist/blob/master/docs/override...
    - cgaebel 4y ago
      Thank you for this. I've made the change, but it looks like it may be several days before github gets around to refreshing the language statistics.
geuis 4y ago
On the website, scrolling doesn't work in mobile safari.
TooSmugToFail 4y ago
Awesome work Clark! Any plans to support Arm in the future? Thanks!
- tbr1 4y ago
  We don't have plans to add ARM support largely because we have no in-house expertise with ARM. That said, ARM has CoreSight which sounds like it could support something like magic-trace in some form, and we'd definitely be open to community contributions for CoreSight support in magic-trace.
gigatexal 4y ago
I’m probably missing something so apologies if this is obvious: does this only work on compiled programs or could it work on any arbitrary running code. Everything from Firefox to my random python script?
- tbr1 4y ago
  It works best on compiled programs. We do try to support scripted languages with JITs that can emit info about what symbol is located where [1]. Notably, this more or less works for Node.js. It'll work somewhat for Python in that you'll see the Python interpreter frames (probably uninteresting), but you will see any ffi calls (e.g., numpy) with proper stacks. [1]: https://github.com/torvalds/linux/blob/master/tools/perf/Documentation/jit-interface.txt https://github.com/torvalds/linux/blob/master/tools/perf/Doc...
zeusk 4y ago
Windows has Windows Performance Analyzer, GPUView and PIX so most game devs are covered on that front :)
- deleted 4y ago
  [deleted]
- djmips 4y ago
  Do people still use GPUView? It hasn't seen a lot of development in years AFAIK and wondered if it was still working and useful. PIX is great! It gets regular updates and an active and responsive Discord channel.
  - zeusk 4y ago
    We use it internally, I'm not entirely certain of external usage. It still works and is good for tracking command packet scheduling and inter-process wait chains. Yup, PIX is THE tool for game developers. Direct3D team also has a very responsive discord channel :)
b20000 4y ago
why do you guys use Caml?
- cgaebel 4y ago
  https://www.youtube.com/watch?v=v1CmGbOGb2I https://www.youtube.com/watch?v=v1CmGbOGb2I
  - b20000 4y ago
    that seems to be a presentation about language features. I'm mostly interested in the business reasons for using the language within what jane street does, and how the language offers a competitive advantage and why it is "good enough" for the highly competitive HFT landscape they work in.
    - brobinson 4y ago
      The language features are the competitive advantage.
- nesarkvechnep 4y ago
  Because Java is not the be-all and end-all.
  - b20000 4y ago
    why use java when you have c++?
    - ARandomerDude 4y ago
      So you can use Clojure. ;-)
la6472 4y ago
So one needs to upload the trace log to your website to visualize? Any way to do it locally?
- tbr1 4y ago
  Absolutely, check out https://github.com/janestreet/magic-trace#privacy-policy https://github.com/janestreet/magic-trace#privacy-policy and https://github.com/janestreet/magic-trace/wiki/Setting-up-a-local-copy-of-the-UI https://github.com/janestreet/magic-trace/wiki/Setting-up-a-.... With a bit of extra configuration, magic-trace can host its own UI locally. You just need to build the UI from source, and point magic-trace to it (via an environment variable).

panosfilianos 4y ago

Thanks for sharing this.

giovannibonetti 4y ago

I'm curious about why Standard ML (SML) was chosen for this project, given the track record Jane Street has with OCaml. Do you seen an advantage for using the former in this kind of project?

tbr1 4y ago
It's all OCaml, GitHub is just misclassifying it as SML :)
- mananaysiempre 4y ago
  Hint[1] in case you’re ever in this situation: echo '*.ml linguist-language=OCaml' >> .gitattributes echo '*.mli linguist-language=OCaml' >> .gitattributes [1] https://github.com/github/linguist/blob/master/docs/overrides.md https://github.com/github/linguist/blob/master/docs/override...
  - cgaebel 4y ago
    Thank you for this. I've made the change, but it looks like it may be several days before github gets around to refreshing the language statistics.

geuis 4y ago

On the website, scrolling doesn't work in mobile safari.

TooSmugToFail 4y ago

Awesome work Clark! Any plans to support Arm in the future? Thanks!

tbr1 4y ago
We don't have plans to add ARM support largely because we have no in-house expertise with ARM. That said, ARM has CoreSight which sounds like it could support something like magic-trace in some form, and we'd definitely be open to community contributions for CoreSight support in magic-trace.

gigatexal 4y ago

I’m probably missing something so apologies if this is obvious: does this only work on compiled programs or could it work on any arbitrary running code. Everything from Firefox to my random python script?

tbr1 4y ago
It works best on compiled programs. We do try to support scripted languages with JITs that can emit info about what symbol is located where [1]. Notably, this more or less works for Node.js. It'll work somewhat for Python in that you'll see the Python interpreter frames (probably uninteresting), but you will see any ffi calls (e.g., numpy) with proper stacks. [1]: https://github.com/torvalds/linux/blob/master/tools/perf/Documentation/jit-interface.txt https://github.com/torvalds/linux/blob/master/tools/perf/Doc...

zeusk 4y ago

Windows has Windows Performance Analyzer, GPUView and PIX so most game devs are covered on that front :)

deleted 4y ago
[deleted]
djmips 4y ago
Do people still use GPUView? It hasn't seen a lot of development in years AFAIK and wondered if it was still working and useful. PIX is great! It gets regular updates and an active and responsive Discord channel.
- zeusk 4y ago
  We use it internally, I'm not entirely certain of external usage. It still works and is good for tracking command packet scheduling and inter-process wait chains. Yup, PIX is THE tool for game developers. Direct3D team also has a very responsive discord channel :)

b20000 4y ago

why do you guys use Caml?

cgaebel 4y ago
https://www.youtube.com/watch?v=v1CmGbOGb2I https://www.youtube.com/watch?v=v1CmGbOGb2I
- b20000 4y ago
  that seems to be a presentation about language features. I'm mostly interested in the business reasons for using the language within what jane street does, and how the language offers a competitive advantage and why it is "good enough" for the highly competitive HFT landscape they work in.
  - brobinson 4y ago
    The language features are the competitive advantage.
nesarkvechnep 4y ago
Because Java is not the be-all and end-all.
- b20000 4y ago
  why use java when you have c++?
  - ARandomerDude 4y ago
    So you can use Clojure. ;-)

la6472 4y ago

So one needs to upload the trace log to your website to visualize? Any way to do it locally?

tbr1 4y ago
Absolutely, check out https://github.com/janestreet/magic-trace#privacy-policy https://github.com/janestreet/magic-trace#privacy-policy and https://github.com/janestreet/magic-trace/wiki/Setting-up-a-local-copy-of-the-UI https://github.com/janestreet/magic-trace/wiki/Setting-up-a-.... With a bit of extra configuration, magic-trace can host its own UI locally. You just need to build the UI from source, and point magic-trace to it (via an environment variable).