Multithreaded memory allocation

[DzmitryFil]

Am i correct in that memory allocation in raytrace demo (and more generally in multithreaded wasm) compiled with wasm-bindgen is currently broken?

dlmalloc-rs wasm implementation assumes that it is run single-threaded, and it's the default memory allocator in wasm at this point.

Am i missing something? @alexcrichton

Considering Lack of atomic.wait on the main thread it looks like the only way for me to use threads with wasm-bindgen is to manually implement allocator that uses mutexes for global lock, and spinlocks if in main thread?

[DzmitryFil]

After looking at sys implementation for wasm i found that allocator is actually always spinlocked, and should be safe to use. Was a bit misled by the comments inside dlmalloc-rs and Multithreading Rust and Wasm blogpost from year earlier. Closing.

[alexcrichton]

Yes looks like you answered your own question! Multi-threaded memory allocation works with a spinlock today. It's pretty bad. There's a nice long comment in the source though explaining why we chose the bad route for now.