As a general rule of thumb, WASM (and therefor Rust) will perform:
- better for compute heavy workloads which don’t need to interop with JS and JS-only APIs
- roughly the same or worse for mixed workloads with highly optimized interop
- worse for JS heavy workloads, no matter how much you optimize
Partly this is because interop has a steep cost that negates the perf benefits in such workloads. Mostly it’s because JS runtimes have very good performance characteristics, beating that is a big feat.
There are certainly performance focused mixed native/JS projects with great potential. Almost all of them are either very light on interop or very heavy on deep understanding of both the native language’s performance advantages and that of the JS runtime (which is often itself very runtime specific).
If you have a lucky workload that doesn’t need to cross interop boundaries much, the world is your oyster. If you have any other workload, you’re probably better off working with whatever you feel most comfortable to deliver and optimize for your use case.
I thought I had read something in the past ~6 months implying that performance gap had become less of an issue, but I'd have to dig for a bit to find it. I understand that I should always expect crossing the WASM boundary to be slow.
I'm basically trying to build something that's like a colony sim meets idleRPG. You define a strategy once per day, submit it, and the colony sim chews on the instructions and plays forward. The user can just observe and devise a plan for adjusting their strategy the next day. I think this makes it an especially good candidate for WASM as I can simulate hundreds of semi-intelligent entities and don't ask for responsive user input.
I think there's also benefits with garbage collecting, right? I can avoid GC entirely with WASM but would inherently be subject to it with JS which then pushes me into a more imperative/mutable style of coding in an effort to preserve object lifetimes. I'd really rather stick to a declarative style if I can get away with the performance.
Calling between JS and WASM isn't really a performance bottleneck anymore in itself [1] (but it is an 'optimization boundary' for the compiler, the same way that a DLL call would be in a native application).
Comments
As a general rule of thumb, WASM (and therefor Rust) will perform:
- better for compute heavy workloads which don’t need to interop with JS and JS-only APIs
- roughly the same or worse for mixed workloads with highly optimized interop
- worse for JS heavy workloads, no matter how much you optimize
Partly this is because interop has a steep cost that negates the perf benefits in such workloads. Mostly it’s because JS runtimes have very good performance characteristics, beating that is a big feat.
There are certainly performance focused mixed native/JS projects with great potential. Almost all of them are either very light on interop or very heavy on deep understanding of both the native language’s performance advantages and that of the JS runtime (which is often itself very runtime specific).
If you have a lucky workload that doesn’t need to cross interop boundaries much, the world is your oyster. If you have any other workload, you’re probably better off working with whatever you feel most comfortable to deliver and optimize for your use case.
I thought I had read something in the past ~6 months implying that performance gap had become less of an issue, but I'd have to dig for a bit to find it. I understand that I should always expect crossing the WASM boundary to be slow.
I'm basically trying to build something that's like a colony sim meets idleRPG. You define a strategy once per day, submit it, and the colony sim chews on the instructions and plays forward. The user can just observe and devise a plan for adjusting their strategy the next day. I think this makes it an especially good candidate for WASM as I can simulate hundreds of semi-intelligent entities and don't ask for responsive user input.
I think there's also benefits with garbage collecting, right? I can avoid GC entirely with WASM but would inherently be subject to it with JS which then pushes me into a more imperative/mutable style of coding in an effort to preserve object lifetimes. I'd really rather stick to a declarative style if I can get away with the performance.
Calling between JS and WASM isn't really a performance bottleneck anymore in itself [1] (but it is an 'optimization boundary' for the compiler, the same way that a DLL call would be in a native application).
[1] https://hacks.mozilla.org/2018/10/calls-between-javascript-a...