Atomics.waitAsync bug #14786
Description
According to the Atomics.waitAsync documentation, it:
verifies that a given position in an Int32Array still contains a given value and if so sleeps, awaiting a wakeup or a timeout.
However, in my testing it seems like the waitAsync doesn't wake (even after calling Atomics.notify).
Moreover, I think that the event loop might be stuck (setTimeout didn't work and the test gets stuck) but I don't have any way to verify that.
Below are the POC files I used to verify that there is a problem.
poc_test.ts
Deno.test(async function poc() {
const ia = new Int32Array(
new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT),
);
const p = Promise.allSettled(
Array(2).fill(0).map((_, i) => {
const name = `poc_worker#${i}`;
const w = new Worker(
new URL("testdata/poc_worker.ts", import.meta.url),
{
type: "module",
name,
},
);
return new Promise<void>((res, rej) => {
w.onmessage = (ev) => {
if (ev.data.ok) res(ev.data);
else rej(ev.data);
};
setTimeout(w.postMessage.bind(w), undefined, ia);
}).finally(w.terminate.bind(w));
}),
);
console.log(await p);
});testdata/poc_worker.ts
export const sleep = (duration: number) => {
return new Promise<void>((res) => {
setTimeout(() => res(), duration);
});
};
self.onmessage = async (ev) => {
const ia = ev.data;
console.log(self.name, ia);
try {
const actual = Atomics.compareExchange(ia, 0, 0, 1);
if (actual === 0) {
await sleep(0);
const notified = Atomics.notify(ia, 0);
console.log(self.name, { actual, notified });
self.postMessage({ ok: true });
} else {
// @ts-expect-error see https://github.com/microsoft/TypeScript/issues/49198
let { async, value } = Atomics.waitAsync(ia, 0, 1);
console.log(self.name, { actual, async, value });
value = await value;
self.postMessage({ ok: true });
}
} catch (err) {
self.postMessage({ ok: false, err });
}
};output
------- output -------
poc_worker#1 Int32Array(1) [ 0 ]
poc_worker#1 { actual: 0, notified: 0 }
poc_worker#0 Int32Array(1) [ 1 ]
poc_worker#0 { actual: 1, async: true, value: Promise { <pending> } }
My Setup
WSL2 - Ubuntu
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.4 LTS
Release: 20.04
Codename: focal
$ deno --version
deno 1.22.1 (release, x86_64-unknown-linux-gnu)
v8 10.3.174.6
typescript 4.6.2