I have two files, main.js and job.js. When a button is clicked in main.js, I want a new, seperate process of the function in job.js to run.
What this process does is launch a new puppeteer browser instance. When the stop button is clicked, this process should be killed by pid. (For this we use process.kill(child.pid)?)
So would I want to use a worker or child process, and if any of those two, how would I implement it so it runs this function?
Important note: every time the start button is clicked, I would like a new process running the function to be started, so the specific process with that pid can be killed.
I suggest you to use a wrapper module for the child_process module. Example usage with execa module.
Main.js
const { execa } = require('execa')
// function for spawning a process with cancel handle!.
async function spawnSubprocess(command, args, cb) {
let subprocess = execa(command, args);
// create a cancel function for later usage!.
function cancel() {
if(subprocess) {
subprocess.kill('SIGTERM', {
// wait for it to terminate before killing it.
forceKillAfterTimeout: 1500
});
// set to null so it won't be killed mutliple times.
subprocess = null
}
}
// add the event listener to subprocess when it's done!
// Can be used for logging or for correctly awaiting a process
// termination before proceeding.
subprocess.then(() => {
subprocess = null
cb()
})
.catch(err => {
subprocess = null
cb(err)
})
// return the cancel handler !.
return cancel
}
// reference to the last cancel. It has to be accessible in
// onClickHandler ofc!.
var processCancel = null
// call this function on click.
// keep the processCancel in scope!
function onClickHandler() {
// first, check if a process is already running
if(typeof processCancel === 'function') {
console.log('Process already running. Calling cancel!')
// the process is not directly terminated. You amy have
// 2 seconds where multiple instances are running but that's not a big deal i guess.
processCancel()
}
// spawn the new process !
// adjust the path to job.js ofc!.
processCancel = spawnSubprocess('node', ['job.js'], (err) => {
// on done callback!. Log some information!.
if(err) {
console.error('Process error ', err)
} else {
console.log('process stopped / DONE')
}
processCancel = null
})
}
This should give you an idea on how to implement it. I suggest to use child_process or any wrapper module. ^^