Ylang: Universal language for eBPF, Stap+, GDB, and more | Hacker News Reader

Ylang: Universal language for eBPF, Stap+, GDB, and more

blog.openresty.com

77 pointswalterbell16 comments

Aside:

> OpenResty XRay

At first I thought -- oh, cool, a suite of tools leveraging LLVM's XRay! But then after digging for a bit, I can't tell exactly what this does or how it does it, but it is not quite clear whether it leverages LLVM's XRay. Oh well, it's interesting enough. Buuuut -- they trademarked 'OpenResty XRay'? Seems like it's on the hairy edge of 'confusingly similar' -- it's definitely intended for tracing/introspection.

OpenResty filed for their trademark in 2020 and LLVM XRay goes back at least to ~2016/2017. OpenResty itself has been around since ~2011? But I couldn't find anything in google regarding OpenResty XRay before 2016.

Anyways, interesting spelunking. To be clear, I'm not suggesting that there's anything wrong. LLVM's license permits this kind of commercialization -- if it were the case here.

Searching on X-?Ray debugging, I see a lot of products from separate vendors so I think it's valid to consider XRay alone a general industry term that is based on an obvious analogy, so disputes hopefully have to relate to an entire trademarked name.

Built with perl6! (Now called raku)

Thanks for pointing this out. To be frank, I would not have expected to see someone highly competent attempting to build a core product with Raku, let alone what looks to be an not entirely trivial compiler. I didn't realize that in addition to being a luajit expert agentzh is also a long-time perl hacker.

Amusingly though he found it necessary to write his own proprietary implementation of (a "dialect" of?) Raku, compiling to luajit byte code.

https://blog.openresty.com/en/ylang-intro-part4/#the-ylang-c...

Very cool.

I'm about to start work on adding eBPF probes to the open source project I maintain for automated Kubernetes troubleshooting (robusta.dev).

Does anyone have good examples of specific data they collected with eBPF probes that would be good to see whenever problems of a certain type occur?

I don't see any parts of this system in openresty's GitHub account. Are some of the components of OpenResty Xray going to be open source?

From https://openresty.com/en/xray/: High CPU Usage Up to 90% reduction in CPU usage

Large Memory Consumption Up to 90% memory footprint reduction, less than 5 minutes to locate memory leaks

Slow Disk I/O Capable of 80% reduction in disk I/O saturation and latency

High Network Latency As much as 90% reduction in response latency and timeout errors

Smells snake oil to me

Cloudflare used and sponsored (2016) OpenResty, which may have motivated performance monitoring for edge efficiency, https://blog.cloudflare.com/first-bay-area-openresty-meetup/

The percentages of improvement that result from finding and tuning the worst paths in a system are often this good unless it has already been done once for the system.. Sun engineers put a lot of thought into algorithms and where bottlenecks should be but still had some improvements like this when first applying DTrace.

They mention java is passing. Does anyone know the status/timeline?

Not associated with the project, but out of curiosity what's your use case?

I don't understand the hype behind lua. I tried scripting vlc plugin and its very painful. No so easy to understand.

I think the hype is mostly excellent C integration. Night and day compared to Python.

What are you comparing it to?

Python, JavaScript.

Lua's a little more opaque than Python or JS, a little more flexible, a little more bug-prone, and a lot simpler. But those aren't the reasons VLC and Wireshark and WoW use Lua instead of Python or JS; they use it because it's enormously less costly to embed. Imagine you decide to switch from Lua to Python for your game. Now you have:

- 3600 kilobytes of bloat instead of 110;

- a huge and bug-prone ABI to deal with to make sure Python doesn't inject memory leaks;

- Python assholes publicly shaming you for using an unfashionable version of Python.

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