Split the wasm file

[takkuumi]

Bevy output wasm is big , 3d-scene wasm file was 14MB, gzip size is 3.6.

Is it possible to split a single wasm file into different modules to better utilize browser network concurrency?

[jakobhellermann]

I don't think this is possible in wasm. There's an open issue with some discussion WebAssembly/design#1166, but I can't find anything else. On other platforms you can also split the debuginfo into a separate file, but that doesn't seem possible on wasm. On a release build you can just remove the debug info instead which further cuts file size: #3978 (comment). With all the options in that comment I can go from 17mb to 1.7mb which might be enough for you.

[takkuumi]

I don't think this is possible in wasm. There's an open issue with some discussion WebAssembly/design#1166, but I can't find anything else. On other platforms you can also split the debuginfo into a separate file, but that doesn't seem possible on wasm. On a release build you can just remove the debug info instead which further cuts file size: #3978 (comment). With all the options in that comment I can go from 17mb to 1.7mb which might be enough for you.

Yes,But there's an other way to resolve this. We can split some standalone module, and then use webworker to post message.

[druskus20]

Wasm code splitting is, to the best of my knowledge, not available in Rust.
There's a 2018 issue discussing it rustwasm/team#52

And it is implemented in C++ https://github.com/WebAssembly/binaryen/blob/102c3633d2378457dae1f5e239fd63ad80eefb92/src/tools/wasm-split/wasm-split.cpp#L339 (and it is used by wasm-opt I believe)

In the case of web at least, the limitation is still lazy loading the modules. https://emscripten.org/docs/optimizing/Module-Splitting.html#running-on-the-web

[jbms]

See this issue where I posted a prototype that addresses exactly this: rustwasm/wasm-bindgen#3939

[daxpedda]

To at least get rid of the debug info, I'm using wasm2map to generate a source map and then strip the debug info from the Wasm file.