Event loop nglakokake JavaScript sampeyan ing siji thread, dadi apa wae sing sinkron lan mbutuhake wektu suwe bakal mblokir — lan sajrone kablokir, Node ora nglayani request, timer, utawa callback liyane. Pamblokiran meh mesthi arupa pakaryan CPU-bound utawa API *Sync, dudu I/O asinkron sing di-await kanthi bener.
*Sync) — fs.readFileSync, fs.writeFileSync, child_process.execSync, zlib.gzipSync. Kabeh iku ngenteni ing panggonan tinimbang masrahake menyang libuv.map/sort/filter array gedhe, matematika matriks, pangolahan gambar/video, parsing/serialisasi struktur raksasa.JSON.parse / JSON.stringify gedhe — sinkron lan O(n); payload pirang-pirang MB mbekukake loop sajrone kabeh proses parse.crypto.pbkdf2Sync, mode sync bcrypt, hashing buffer gedhe ing thread utama.while (true), rekursi tanpa wates, for ing yutan item kanthi pakaryan saben item.// Kabeh iki mblokir loop — ora ana request liya sing dilayani sajrone iku:
const data = fs.readFileSync("big.json"); // I/O sinkron
const obj = JSON.parse(hugeString); // parse gedhe
const hash = crypto.pbkdf2Sync(pw, salt, 1e6, 64, "sha512"); // kripto sinkron
for (let i = 0; i < 1e9; i++) { /* CPU */ } // loop ketat
Mbungkus pakaryan CPU ing fungsi
asyncora mbantu —asyncmung masrahake kendali ingawait; body sinkron tetep mlaku nganti rampung ing thread loop.
perf_hooks.monitorEventLoopDelay() utawa library kaya blocked-at; lag sing mundhak tegese ana sing nguwasani thread.node --prof, clinic doctor/clinic flame, CPU profile Chrome DevTools kanggo nemokake frame sinkron sing panas.*Sync (fs.promises.readFile, crypto.pbkdf2, zlib.gzip).worker_threads, child process, utawa queue/service eksternal.setImmediate/await supaya loop bisa ambegan ing antarane batch.const { Worker } = require("node:worker_threads");
// Offload hash sing larang supaya loop tetep responsif.
const worker = new Worker("./hash-worker.js", { workerData: { pw, salt } });
Ing Node, siji panggilan sing mblokir ngukum saben klien sing bebarengan, ora mung request sing nyebabake — latensi mundhak, health check timeout, lan proses katon "hang" nalika beban dhuwur. Pewawancara takon iki kanggo ndeleng apa sampeyan bisa nyebutake blocker konkret (*Sync, JSON.parse gedhe, kripto sinkron, ReDoS, loop CPU), ndeteksi nganggo tooling event-loop-lag, lan mbenerake kanthi ngalih menyang async utawa ngoffload menyang worker threads. Iki minangka kegagalan performa Node sing paling umum ing production.
Pustaka pitakon wawancara IT kanthi jawaban rinci — saka Junior nganti Senior.
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