Infinite async loops using setInterval() [duplicate]

Question

I have nodejs app that needs a few infinite loops which call async functions. I was considering implementing the following:

async function execute1() {
   ...do some async work...
}

async function execute2() {
   ...do some async work...
}

setInterval(execute1, 500)
setInterval(execute2, 500)

My concern is that if the async functions will take a long time to complete, the open references will pile up and this can result in a memory crash down the line.

1. is setInterval the right tool for this job? is there a more suitable tool?
2. What is the most elegant method to make sure the execute() function will not start if the previous run hasn't return?

Answer 1

setInterval isn't the right tool because it's unaware of promises and can't maintain correct control flow.

It can be async function with infinite loop:

async function execute1() {
  while (true) {
    await new Promise(resolve => setTimeout(resolve, 500));
    // ...do some async work...  
  }
}

execute1();

Answer 2

setTimeout might work better in this case.

async function execute1(delay) {
   // await ...
   setTimeout(() => execute1(delay), delay)
}
execute1(500)

Answer 3

you can use simple flags to indicate whether the previous function is still running

let isRunning = false;

async function execute1() {
   if (isRunning) return;
   isRunning = true

   ...do some async work...

   // make sure to call this whether it succeeds or fails, maybe in a finally block
   isRunning = false
}

setInterval(execute1, 500)

Answer 4

You can create a function that will run your execute1(), then wait for it's completion, then run itself with setTimeout().

function randomSleep() {
  return new Promise(resolve => setTimeout(resolve, Math.random() * 3000));
}

let done = 0;

async function execute1() {
   console.log('Execute 1 started.')
   await randomSleep()
   return 'done'
}

const run = () => {
  execute1().then(result => {
    console.log('Execute 1 ended')
    done++
    console.log(`Done ${done} times.`)
    console.log(`Now waiting for 2 seconds`)
    setTimeout(() => {
      run()
    }, 2000)
  })
}

run()