Azure-functions-host: Timer function doesn't get triggered every hour

[estruyf]

Hi,

I have an Azure function which gets triggered every hour (normally it should only be four times a day). The cron job is configured as follows: "0 0 */1 * * *".

If you check the attached screenshot, you'll see that the job doesn't run every hour. At 12:00 everything is ok, because then I configured the function. At 13:21 the job started a bit later because another job got triggered (http trigger). That seems to have woken up the timer function and so it successfully ran.

Function didn't get executed at 15:00. At 16:00 I logged on to the Azure portal, again this have woken up the timer function.

At 19:20 again the same HTTP trigger function got called. Same story all over.

Is this issue coming from the fact that by default the always-on functionality is turned off?

[davidebbo]

Is you function app Dynamic or in Classic mode? If Classic, what sku is it using? e.g. Free/Shared/Basic/Standard

[estruyf]

Configured in dynamic mode.

[davidebbo]

Hmmm, then it doesn't make sense. Normally, there is no need for Always On in dynamic (in fact, it's not even available). Your Function App should be kept running automatically to take care of timers.

Could you share the Function App name? You can create a test one with the same issue if you prefer not to share your main one.

[estruyf]

Function app name: functionsf9516c96 - TimerTriggerNodeJS2 is the function in which I configured the test.

[cgillum]

You mentioned that there is also an HTTP trigger in this function app. We recently discovered a bug that can cause similar problems when a function app contains timer triggers as well as other trigger types.

Could you try creating a separate function app which contains only your timer trigger function(s) and see if that makes it more reliable?

[brettsam]

@cgillum / @estruyf -- Do you still see this happening?

[SeanFeldman]

Still an issue.

[brettsam]

Thanks for the report @SeanFeldman. The fix for this hasn't been deployed yet but will be soon. We'll update this issue when it's deployed and see if anyone is still seeing the problem.

[brettsam]

The fix is is now deployed so I'll close this issue. If anyone continues to see this, please reactivate so we can investigate.

[JoeBrockhaus]

@brettsam I'm seeing similar odd behavior with this trigger - rather than not triggering, it's triggering more than 1 time every hour - usually 2 or 3 times within a minute or so.

My FuncApp is on a Consumption Plan and only has 2 functions; both configured to trigger every hour, using TimerTrigger("0 0 * * * *")

I've previously had RunOnStartup = true, which seems like it might explain why the most recent execution in the screenshot fired a 4th, seemingly random time .. this would be when I navigated to the Function App in the Portal. (Seems odd this would 'wake-up' the app, but 🤷‍♂️ )

edit: I just removed RunOnStartup, and also updated Functions.Sdk from 1.0.0-alpha4 to 1.0.0-alpha6.
I'll give this a test and see if it still occurs.

[brettsam]

@JoeBrockhaus -- thanks for the report. If you continue seeing this with your newest deployment, can you open up a new issue (and feel free to mention me so I get pinged right away). If you can give a timerange and your function app name (either directly or indirectly), that'd help me look through our logs to see if I can figure out what's happening.

[JoeBrockhaus]

thanks @brettsam these latest updates (1.0.0-alpha6 & RunOnStartup = false ) so far have brought it back to the single execution. 🥂