Sharing Across Agents

Workers that share the heap, and messages between them that carry shared objects as themselves.

The proposal leaves sharing across agents to the host. @arv/structs/agent starts workers that attach to the same heap: worker_threads in Node, module Web Workers in a browser. Messages sent through it carry shared objects as themselves, and everything else as postMessage copies it.

// main.js
import {startWorker} from '@arv/structs/agent';
const w = startWorker(new URL('./worker.js', import.meta.url));
w.postMessage({tally, n: 1000});

// worker.js
import {parent} from '@arv/structs/agent';
parent.onmessage = ({tally, n}) => {
  /* tally is the main thread's struct */
};

run(url, name, ...args) calls the function a module exports as name on a worker and settles with what it returns. A module can run its own functions with run(import.meta.url, ...). The workers are a pool: one that returns waits for the next call, with the code V8 has optimized in it, so a program that runs its work again finds its workers warm. Each worker imports the module, so its top-level code runs there too: keep what only the main thread does in a function, or behind if (!parent).

examples/counter has four workers counting to a million under a Mutex, with a Condition saying when they are done.