Spidermonkey memory leak in async functions. Run in JS Shell.

spidermonkey-async-function-leak.js

let nextId = 0;

let weakMap;
let savedCallback;

function createWeakMap(callback) {
    weakMap = new WeakMap();
    savedCallback = callback;
}

const tests = [
    // Success
    function() {
        let object = { id: ++nextId };
        console.log(`created object ${object.id}`);
        createWeakMap(() => {});
        weakMap.set(object, object.id);
    },
    // Success
    async function() {
        let object = { id: ++nextId };
        console.log(`created object ${object.id}`);
        createWeakMap(() => {});
        weakMap.set(object, object.id);
        object = undefined;
    },
    // Fails
    async function() {
        let object = { id: ++nextId };
        console.log(`created object ${object.id}`);
        createWeakMap(() => {});
        weakMap.set(object, object.id);
    }
];

(async () => {
    for (const test of tests) {
        await test();
        assertEq(nondeterministicGetWeakMapKeys(weakMap).length, 1);
        gc();
        if (nondeterministicGetWeakMapKeys(weakMap).length !== 0) {
            console.log(`Error: object ${nextId} could not get collected`);
        }
    }
})();

v8-async-function-no-leak.js

let nextId = 0;

let weakRef;
let savedCallback;

function createWeakMap(callback) {
    savedCallback = callback;
}

const tests = [
    // Success
    function() {
        let object = { id: ++nextId };
        console.log(`created object ${object.id}`);
        createWeakMap(() => {});
        weakRef = new WeakRef(object);
    },
    // Success
    async function() {
        let object = { id: ++nextId };
        console.log(`created object ${object.id}`);
        createWeakMap(() => {});
        weakRef = new WeakRef(object);
        object = undefined;
    },
    // Success
    async function() {
        let object = { id: ++nextId };
        console.log(`created object ${object.id}`);
        createWeakMap(() => {});
        weakRef = new WeakRef(object);
    }
];

(async () => {
    for (const test of tests) {
        await test();
        if (!weakRef.deref()) {
            console.log(`Can't check object, it's gone`)
        }
        await new Promise(resolve => setTimeout(resolve, 0))
        gc();
        if (weakRef.deref()) {
            console.log(`Error: object ${nextId} could not get collected`);
        }
    }
})();