Worker threads omogočajo Node, da izvaja JavaScript na ločenih nitima s pravim paralelizmom — in reševati Nodeovo največjo omejitev: CPU-intenzivna opravila, ki blokirajo en sam glavni thread (in s tem vse zahteve). Jih uporabite za težke izračune, ne pa za I/O (kar event loop že učinkovito obravnava).
app.(, {
result = ();
res.(result);
});
Node vaš JS izvaja na enem threadu. Dolgo sinhronega izračuna blokira vse — event loop ne more procesirati drugih zahtev, dokler se ne zaključi. Worker threads to opravilo premakne z glavnega threada.
// main.js
import { Worker } from "worker_threads";
function runHeavyTask(data) {
return new Promise((resolve, reject) => {
const worker = new Worker("./worker.js", { workerData: data }); // runs on a NEW thread
worker.on("message", resolve); // receive the result
worker.on("error", reject);
worker.on("exit", (code) => { if (code !== 0) reject(new Error(`exit ${code}`)); });
});
}
// the main thread stays free to handle other requests while this runs
const result = await runHeavyTask({ numbers: [...] });
// worker.js — runs in parallel, on its own thread
import { workerData, parentPort } from "worker_threads";
const result = expensiveComputation(workerData); // doesn't block the main thread
parentPort.postMessage(result); // send the result back
Worker se izvaja neodvisno; glavni thread še naprej služi zahtevam in dobi rezultat prek sporočila, ko se zaključi.
✓ USE for CPU-bound work: image/video processing, encryption, compression,
big data parsing, complex calculations, ML inference
✗ DON'T use for I/O (DB, files, HTTP) — the async event loop already handles
that efficiently; a worker would add overhead for no benefit
Pravilo: worker threads za CPU-bound, event loop za I/O-bound.
worker_threads → share memory (efficient data passing), in-process threads — CPU work
child_process → separate OS processes, run other programs — heavier isolation
cluster → fork the whole server across CPUs — scale request handling
Worker threads naslovljajo Nodeovo temeljno šibkost — CPU-bound naloge, ki blokirajo enonitnati event loop in zamrznejo vse sočasne zahteve.
Znanje, kako težke izračune preložiti na worker (ob tem ko ohranite glavni thread odziven) in kritično kdaj jih uporabiti (samo CPU-bound, nikoli za I/O), je tisto, kar Nodeovemu storitev omogoči, da obvladuje občasno težko obdelavo brez žrtovanja sočasnosti, ki naredi Node dragocen.
Za oblikovanje worker threadov v produkciji knjižnice, kot je Piscina, učinkovito upravljajo pool threadov.