That’s how the people working on the project characterized it.
In the meantime the CLR happened too.
And - to an extent - LLVM IR.
Security wise, perhaps a different story, though let's wait until WASM is in wide use with filesystem access and bugs start to appear.
By comparison, WASM is really more like traditional assembly, only running inside a sandbox.
> it seemed quite natural to use the triple-dot forwarding syntax (...).
> Unfortunately I found that using ... was quite expensive
> This lead me to implement an optimization for ... .
That’s some excellent yak shaving. And speaking up … in any language is good news even if allocation is not faster.
That’s dangerous thinking because constructors will be a bimodal distribution.
Either a graph of calls or objects will contain a large number of unique objects, layers of alternating objects, or a lot of one type of object. Any map function for instance will tend to return a bunch of the same object. When the median and the mean diverge like this your thinking about perf gets muddy. An inline cache will make bulk allocations in list comprehensions faster. It won’t make creating DAGs faster. One is better than none.
Not necessarily. An inline cache is cheap but it's not free, even less so when it also comes with the expense of moving Class#new from C to Ruby. It's probably not worth speeding up the 1% at the expense of the 99%.
> An inline cache will make bulk allocations in list comprehensions faster.
Only if such comprehensions create exactly one type of object, if they create two it's going to slow them down, and if they create zero (just do data extraction) it won't do anything.
We just had this conversation maybe a month ago. If it’s 50-50 then you are correct. However if it’s skewed then it depends. I can’t recall what ratio was discovered to be workable, it was more than 50% and less than or equal to 90%.
Yes, but if it ends up creating any ephemeral objects in the process of determining those returned objects, then the allocation sequence is still not homogeneous. In Ruby, according to the article, even calling a constructor with named arguments allocates, so it's very easy to still end up cycling through allocating different types.
At the same time, the callsite for any given `.new()` invocation will almost always be creating an instance of the exact same class. The target expression is nearly always just a constant name. That makes it a prime candidate for good inline caching at those callsites.
alberth•5h ago
And if so, will these YJIT features likes Fast Allocations be brought to ZJIT?
https://railsatscale.com/2025-05-14-merge-zjit/
firemelt•5h ago
and the features is there when its there
ksec•5h ago
I guess YJIT will always be faster in warmup and minimal increase of memory usage. ZJIT being more traditional should bring more speedup than YJIT.
But most of the speedup right now is still coming from rewriting C into Ruby.
uticus•3h ago
Quick glance, this statement seems backwards - shouldn't C always be faster? or maybe i'm misunderstanding how the JIT truly works
vidarh•3h ago
EDIT: Note that this isn't an inherent limit. You could write a JIT that could analyze the compiled C code too. It's just that it's much harder to do.
molf•3h ago
Crossing the Ruby -> C boundary means that a JIT compiler cannot optimize the code as much; because it cannot alter or inline the C code methods. Counterintuitively this means that rewriting (certain?) built-in methods in Ruby leads to performance gains when using YJIT. [2]
[1]: https://railsatscale.com/2023-08-29-ruby-outperforms-c/ [2]: https://jpcamara.com/2024/12/01/speeding-up-ruby.html
nightpool•38m ago
uticus•8m ago
this is fascinating to me. i always assumed C had everything in the language that was needed for the compiler to use. in other words, the compiler may have a lot to work through, but the pieces are all available. but this makes it sound like JIT'd functions provide more info to the compiler (more pieces to work with). is there another language besides C that does have language features to indicate to the compiler how to make things as performant as possible?
tenderlove•4h ago
ZJIT is a method based JIT (the type of compiler traditionally taught in schools) where YJIT is a lazy basic block versioning (LBBV) compiler. We're using what we learned developing and deploying YJIT to build an even better JIT compiler. IOW we're going to fold some of YJIT's techniques in to ZJIT.
> And if so, will these YJIT features likes Fast Allocations be brought to ZJIT?
It may not have been clear from the post, but this fast allocation strategy is actually implemented in the byte code interpreter. You will get a speedup without using any JIT compiler. We've already ported this fast-path to YJIT and are in the midst of implementing it in ZJIT.
FooBarWidget•3h ago
tenderlove•2h ago
ysavir•1h ago
strzibny•1h ago