This code caused a segmentation fault in a one-off occurance. Fixed by fixing the TypeError that is thrown first by line 33 of script.js

qsort.js

const {
  Worker, isMainThread, parentPort, workerData, threadId, MessageChannel
} = require('worker_threads')
//getting array from workerData
const array = workerData
// sort array
let sortedArray = array.sort((a, b) => a - b)
let thr = {
  threadId,
  sortedArray
}
//send back to parent using parentPort.postmessage
parentPort.postMessage(thr)

script.js

const assert = require('assert')
const { EventEmitter } = require('events')
const { Worker, isMainThread, parentPort, workerData } = require('worker_threads')

const MAX_THREAD_COUNT = 8
const nThreads = parseInt(process.argv[2])
assert(nThreads <= MAX_THREAD_COUNT, `Number of threads cannot exceed ${MAX_THREAD_COUNT}`)
const data_fileName = process.argv[3]

const DATA = [
  7, 12, 19, 3, 18, 16, 4, 2,
  6, 9, 18, 38, 15, 8, 123, 72,
  4, 3, 11, 33, 15, 48, 13, 17,
  23, 19, 30, 45, 31, 1, 14, 50
]

// split up data in nThreads equal parts
const data_split = []
const s = DATA.length / nThreads // size of sub array
for (let i = 0; i < DATA.length; i+=s)
  data_split.push(DATA.slice(i, i+s))

// event listener
const sortEmitter = new EventEmitter()

sortEmitter.on('sorted', ({ threadId, sortedArray }) => {
  console.log(`threadId: ${threadId} | -> sortedArray: ${sortedArray}`)
})

// send data to qsort threads
data_split.forEach(subArray => {
  let qsortThread = new Worker('./qsort.js', { workerData: subArray })
  qsortThread.on('message', res => sortEmitter('sorted', res))
})