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Last week I gave Porffor shared-everything threads: one heap, every object shared, races allowed but never a torn value. github.com/arv/porffor/tree/arv/shared-everything-threads/threads This week, the opposite bet: @arv/threads, threads for plain TypeScript on Web Workers 🧵 threads.arv.tools

threads.arv.toolsThreads DocsThreads for JavaScript, in plain TypeScript, on Web Workers and a SharedArrayBuffer.

15/10/26, 1:23 pm0 reposts0 likes

arv

@arv.tools

Why the opposite? I first tried Porffor’s model in plain JS on Web Workers. Workers can’t share V8 objects, so an object had to move into shared memory as soon as a second thread could see it. It worked, but reading a shared object got ~17x slower.

arv

@arv.tools

So now every value is one of three kinds: • owned by one thread, and it moves • deeply immutable, copied once per reader • a struct or SharedArray, laid out in shared memory Ordinary code is plain JS. On 8 threads, Mandelbrot runs 7.6x faster than single-threaded JS, and N-body 4x.

arv

@arv.tools

A checker on TypeScript 7 proves the rules: no use after a move, no mutable object reaching two threads. A Vite plugin compiles shared structs down to typed-array reads and writes.

arv

@arv.tools

Try it in the browser, the TypeScript and the JS it compiles to side by side: threads.arv.tools/playground/ npm install @arv/threads. Still experimental: the compiler is a tsgo fork you build yourself, for now. Built mostly by iterating with Claude Code.

threads.arv.toolsThreads playground