Timer trigger firing multiple times

Question

Hello, our time trigger is firing multiple times.

first

Executing 'WorkItemEMailNotifier.SendNotificationsAsync' (Reason='Timer fired at 2023-11-27T06:30:00.6130744+00:00', Id=1b8ea6f5-4fbd-48f9-9cd3-bef1a60ffe96)

cloud_RoleInstance

f0077431910fb6dea54963132eadf2a2b43ec72473ce6346f6fc7962f841ea80

I think that id is the invocation id?

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second

Executing 'WorkItemEMailNotifier.SendNotificationsAsync' (Reason='Timer fired at 2023-11-27T07:12:39.7954045+00:00', Id=eceebd57-9a4c-4a16-b9c2-004535d73526)

cloud_RoleInstance

03b1956e540c7298eb7ea1dd3fe97bd73e508a1d418997c00ed4bd3df4054cdc

Trigger Details: UnscheduledInvocationReason: IsPastDue, OriginalSchedule: 2023-11-27T06:30:00.0000000+00:00

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third

Executing 'WorkItemEMailNotifier.SendNotificationsAsync' (Reason='Timer fired at 2023-11-27T07:36:52.7149523+00:00', Id=9be103dd-1af8-4c8d-9b52-620e38a0dac6)

cloud_RoleInstance

1357526e1782d62b35eb99cb2b065bf74fce4febbb54db61f298b49f3f9023a0

Trigger Details: UnscheduledInvocationReason: IsPastDue, OriginalSchedule: 2023-11-27T06:30:00.0000000+00:00

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I see the cloud_RoleInstance is diefferent every time, so is it firing off of new instances spun up or something?

Answer 1

Hi @Adam Day - These may not be the same trigger event from multiple instances as the following is stated on the matter:

The timer trigger uses a storage lock to ensure that there is only one timer instance when a function app scales out to multiple instances. If two function apps share the same identifying configuration and each uses a timer trigger, only one timer runs.

Rather, they seem like executions from missed invocations:

The isPastDue property is true when the current function invocation is later than scheduled. For example, a function app restart might cause an invocation to be missed.

You might check why the invocations were missed (whether they originate from transient, non-blocking cause vs persistent issue that needs to be mitigated) and leverage the isPastDue flag for gracefully handling the scenario in your code. Hope this helps!

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Answer 2

This may apply TimerTrigger in Azure Function in Docker container on Kubernetes runs on every instance (.NET Core)