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2-deadlock.js
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71 lines (62 loc) · 1.91 KB
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'use strict';
const threads = require('node:worker_threads');
const { Worker, isMainThread } = threads;
const LOCKED = 0;
const UNLOCKED = 1;
class Mutex {
constructor(shared, offset = 0, initial = false) {
this.lock = new Int32Array(shared, offset, 1);
if (initial) Atomics.store(this.lock, 0, UNLOCKED);
this.owner = false;
}
enter(callback) {
Atomics.wait(this.lock, 0, LOCKED);
Atomics.store(this.lock, 0, LOCKED);
this.owner = true;
setTimeout(callback, 0);
}
leave() {
if (!this.owner) return;
Atomics.store(this.lock, 0, UNLOCKED);
Atomics.notify(this.lock, 0, 1);
this.owner = false;
}
}
// Usage
if (isMainThread) {
const buffer = new SharedArrayBuffer(8);
const mutex1 = new Mutex(buffer, 0, true);
const mutex2 = new Mutex(buffer, 4, true);
console.dir({ mutex1, mutex2 });
new Worker(__filename, { workerData: buffer });
new Worker(__filename, { workerData: buffer });
} else {
const { threadId, workerData } = threads;
const mutex1 = new Mutex(workerData);
const mutex2 = new Mutex(workerData, 4);
if (threadId === 1) {
mutex1.enter(() => {
console.log('Entered mutex1 from worker1');
setTimeout(() => {
mutex2.enter(() => {
console.log('Entered mutex2 from worker1');
if (mutex1.leave()) console.log('Left mutex1 from worker1');
if (mutex2.leave()) console.log('Left mutex2 from worker1');
});
}, 100);
});
} else {
mutex2.enter(() => {
console.log('Entered mutex2 from worker2');
// Uncomment to fix deadlock
// if (mutex2.leave()) console.log('Left mutex2 from worker2');
setTimeout(() => {
mutex1.enter(() => {
console.log('Entered mutex1 from worker2');
if (mutex2.leave()) console.log('Left mutex2 from worker2');
if (mutex1.leave()) console.log('Left mutex1 from worker2');
});
}, 100);
});
}
}