Why is my Firebase scheduled function not running every minute?

Question

I have a firebase function that looks like like this:

export const syncDataScheduled = onSchedule({
  schedule: "every 1 minutes",
  timeoutSeconds: 70, //we don't want the function to run for longer than 1 minute (will give it some extra time for cleanup)
  maxInstances: 5,
  timeZone: 'America/New_York',
  concurrency: 5,
}, async () => {

  let terminateFunction = false;
  // firebase functions can only run max every minute, so we need to loop for 1 minute since we want to run this every 3 seconds.
  setTimeout(() => terminateFunction = true, 59_000);

  while (true) {
    // we don't want the function to run for longer than 1 minute, since we schedule it to run every minute anyway.
    if (terminateFunction) break;
    await syncData();
    await new Promise(resolve => setTimeout(resolve, 3_000));
  }
});

I want to sync some company data every 3 seconds. But since Google Firebase functions has a minimum schedule time of every one minute, I have to loop till the minute is up.

The problem is, that Firebase sometimes skips a run. Which means that the function doesn't run for a whole minute.

See below the gaps in logs.

Can anyone help?

Answer 1

Turns out, the issue was that we used the fetch API on Node 18, which is experimental. This function makes around 12 http requests using fetch every 3 seconds, and sometimes a promise returned from one of the fetch calls wouldn't "fulfill" - meaning, it wouldn't either resolve or reject.

I simply changed the Node version number from 18 to 20, and it started working just fine.