How to calculate the execution time of a async method in JavaScript?

Question

I have a node file which contains many methods including a Async call method which fetches data from db. I need to find the exact execution time of it.

So i tried,

.
.
var start = Date.now();
await dbFetching()
var end = Date.now();
console.log(end - start)
.

Then I tried with an external shell script which executes the file and find the actual time execution of the entire file execution. But the issue is i need to calculate only the time taken for the Async call (dbFetching). Below is my shell script,

#!/bin/sh

START=$(date +%s)
node ./s3-glacier.js
END=$(date +%s)
DIFF=$(( $END - $START ))
echo "It took $DIFF seconds"

But i though like, if i can run entire node script in the shell script, May be i can calculate the time. Therefore suggest your thought on this to calculate only the Async time consumption. Thanks in advance

"I need to find the exact execution time of it." Don't rely on one measurement of an async call. If you try 100 repetitions, you may see quite a spread of times. Quite a bit happens internally and there are various sources of randomness. Beware. — Paul, May 21 '21 at 07:47
yes. It doesn't matter if the time change for every iterations. But i need to find an execution time of a single async call — ahkam, May 21 '21 at 08:02

score 0 · Answer 1 · answered May 21 '21 at 07:43

If you have this possibility - use async/await. It would look like:

var start = Date.now();
await dbFetching(); // blocks execution of code
var end = Date.now(); // this happens AFTER you've fetched the data
console.log(end - start)

That would require your function to be marked as async though, or return a Promise.

Otherwise you'd need to pass a callback to a function, so that the function calls it when it's done and you know that it's now time to calculate the dime. Something along the lines of:

var start = Date.now();
dbFetching(function done() { // done should be called AFTER the data is fetched
  var end = Date.now();
  console.log(end - start)
})

actually i forgot to mentioned that the function is properly handed with async await scenario. But the fetching takes too time than the console time difference. It's because of the async behaviour — ahkam, May 21 '21 at 07:52

How to calculate the execution time of a async method in JavaScript?

1 Answers1