Worker threads are not running in Node.js - node.js

Question

I am trying to implement a basic matrix multiplication using worker threads with a limit of 10 threads. But the threads which are not worker threads are not responding at all.
Matrix A and B are filled with random number generator.
if (isMainThread) {
const M = 100;
const N = 100;
const matrixA = [];
for (let i = 1; i <= M; i++) {
// random numbers for each element of mat A
}
const matrixB = [];
for (let i = 1; i <= M; i++) {
// random numbers for each element of mat B
}
let matCCount = 0;
const totalCount = (M * N);
const matrixC = [];
const time1 = new Date();
let threadCount = 0;
const calculateResult = (matrixC) => {
const time2 = new Date();
console.log(`\nTime taken: ${(time2 - time1) / 1000}s`);
}
const mainService = function(getResult) {
for (let i = 0; i < M; i++) {
for (let j = 0; j < N; j++) {
let success = false;
do {
if (threadCount < 11) {
const worker = new Worker(__filename, { workerData: { i, j, matrixA, matrixB } });
threadCount ++;
worker.on('message', (message) => {
getResult(message);
success = true;
threadCount --;
});
worker.on('online', () => { console.log('online'); })
worker.on('error', (err) => {
console.log(err);
});
worker.on('exit', (code) => { console.log(code); })
}
} while (!success);
}
}
}
mainService((res) => {
const { i, j, result } = res;
if (matrixC[i] === undefined) {
matrixC[i] = [];
}
matrixC[i][j] = result;
matCCount += 1;
if (matCCount === totalCount) {
calculateResult(matrixC);
}
});
} else {
const { i, j, matrixA, matrixB } = workerData;
const x = multiplyOperation(i, j, matrixA, matrixB);
parentPort.postMessage({ i, j, result: x, threadId });
}
neither 'online' event is fired nor this console.log runs
} else {
console.log(threadId);
const { i, j, matrixA, matrixB } = workerData;
const x = multiplyOperation(i, j, matrixA, matrixB);
parentPort.postMessage({ i, j, result: x, threadId });
}