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>> we were able to allow UNIX-like threading to run via JS Workers by reusing the shared memory from the main WebAssembly process and notifying the memory upon changes (using Wasm notify/wait syntax).

This left me scratching my head. How are JS workers sharing memory with the WASM process?

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JS has an API called "SharedArrayBuffer" that allows sharing memory between processes or threads (with the aid of the host)

I wonder how much of a perf hit a normal multithreaded Unix application would take because of this model. Are there any data points around the multi-threading perf here?

Usually it adds an extra 10-25% of overhead when the WASIX program uses systemcalls that require unwind/rewind functionality (this is for fork and subprocesses mainly, the multithreaded ones doesn't require asyncify and as such should not experience a performance hit)

I believe JS workers are actually implemented as threads, so the performance overhead might not be as bad as you'd expect.

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