kapretest2.js

const {
    Worker
} = require('worker_threads');


// const NUM_WORKERS = os.cpus().length;
const NUM_WORKERS = 12;

const START = 100;

const END = 1_000_000_000;
const CHUNK_SIZE = Math.ceil((END - START) / NUM_WORKERS);


let completedWorkers = 0;

console.log(`Starting ${NUM_WORKERS} workers...`);
console.log(`Range: ${START} to ${END}`);
console.time('Total time');
const completed = []
for (let i = 0; i < NUM_WORKERS; i++) {
    const rangeStart = START + i * CHUNK_SIZE;
    const rangeEnd = Math.min(rangeStart + CHUNK_SIZE, END);

    const worker = new Worker("./kapre.js", {
        workerData: {
            rangeStart,
            rangeEnd,
            workerId: i + 1,
        }
    });

    worker.on('message', ({
        workerId,
        seen
    }) => {
        console.log(`Worker ${workerId} completed`);
        console.log(workerId, seen)
        completed.push(seen)
    });

    worker.on('error', err => console.error(`Worker ${i + 1} error:`, err));

    worker.on('exit', () => {
        completedWorkers++;
        if (completedWorkers === NUM_WORKERS) {
            console.timeEnd('Total time');
            console.log(completed)
        }
    });
}
///worker
const {
    parentPort,
    workerData
} = require('worker_threads');

const {
    rangeStart,
    rangeEnd,
    workerId,
} = workerData;

console.log(workerId, 'started')
const maxNum2 = num => {
  const count = new Uint8Array(10);
  for (let n = num; n > 0; n = n / 10 | 0) count[n % 10]++;
  
  let result = 0;
  for (let d = 9; d >= 0; d--) 
    while (count[d]--) result = result * 10 + d;
  
  return result;
}
const minNum2 = num => {
  const count = new Uint8Array(10);
  for (let n = num; n > 0; n = n / 10 | 0) count[n % 10]++;
  
  let result = 0;
  for (let d = 0; d <= 9; d++) 
    while (count[d]--) result = result * 10 + d;
  
  return result;
}


const seen = {};
const MAX_STEP = 10_000;

const findKaprekar = (i, _min, _max, prev, step) => {
    let diff = _max-_min;
    while (diff) {
        if (diff in seen) {
            break;
        }
        if (step > MAX_STEP) {
            seen[diff] = -i;
            break;
        }
        if (prev===diff) {
            seen[diff] = i;
            break;
        }
        prev = diff;
        diff = maxNum2(diff)-minNum2(diff);
        step++;
    }
}

for (let i = rangeStart; i< rangeEnd; i++) {
    findKaprekar(i, minNum2(i), maxNum2(i), null, 1);
    if ((i % 1_000_000)===0){
        console.log(i.toLocaleString(), seen)
    }
}

console.log(seen);

parentPort.postMessage({
    workerId,
    seen
});

{
'495': 102,
'6_174': 1001,
'549_945': 100155,
'631_764': 100147,
'63_317_664': 10001567,
'97_508_421': 10000024,
'554_999_445': 333333888,
'864_197_532': 333333401,
}