Function App on TimerTrigger does not fire on the hour every hour

[danpetitt]

We have a function set to run on a timer trigger on the hour; however some hours it fires a few seconds early and other hours it does not fire at all as can be seen in this screenshot, you can see that nothing was fired at all at 21:00 last night, or 1am or 8am this morning

We are relying on this firing accurately on the hour, even if its a few seconds late is okay so long as its on the hour before the minute past; but certainly not early or missing completely.

We are running the app in our App Service Environment and it is set to "Always On".

Investigative information

Please provide the following:

• Timestamp: 2022-03-22 21:00 / 2022-03-23 01:00 / 2022-03-23 05:00 / 2022-03-23 08:00
• Function App version: Runtime Version ~2
• Function App name: PawaDatabaseJobs
• Function name(s) (as appropriate): timed-exports
• Invocation ID: obviously havent got one for missing invocations, but here is one for one just before: Executing 'Functions.timed-exports' (Reason='Timer fired at 2022-03-23T04:59:59.9963753+00:00', Id=d30761f4-cd5b-4b4f-9650-824ae31df011)
• Region: North Europe

Repro steps

Not really reproducible, but you can see the issue in the screenshot and the bindings below.

Expected behavior

A timer trigger is fired on the hour every hour.

Actual behavior

The timer is not firing every hour and sometimes its a few seconds before, but the missing triggers are the most important.

Related information

Provide any related information

• Programming language used : Node
• Links to source
• Bindings used:

  "bindings": [
    {
      "name": "EveryHour",
      "type": "timerTrigger",
      "direction": "in",
      "schedule": "0 0 * * * *"
    }
  ],

[Ved2806]

Hi @danpetitt Thank you for the feedback. we will discuss this issue internally and let you know about the findings soon!

[anirudhgarg]

How long does it take to run ?

[danpetitt]

@anirudhgarg between 1 and 3 seconds (see below); would it be affected by length of time any other functions running on the same app would be taking as I havent checked that, but I dont expect anything to be taking hours to run...

[Ved2806]

Hi @danpetitt, we are discussing this issue internally, we will let you know about the findings soon

[Yash-Poddar]

Hi @danpetitt, have you got any lead on this? I'm facing a similar issue

Hi @Ved2806, have you guys reached to any conclusions after internal discussions?

I have multiple timer triggers, all 3 of them (scheduled to run every hour) are behaving weirdly (not firing every hour) similar to the above mentioned issue.

[danpetitt]

@Yash-Poddar nope, heard nothing from this thread and support just went quiet and haven't heard a thing. Contemplating moving it to aws which appears much more reliable which is a shame as we spend over £20k per month with azure