Disable automatic creation of observation on some scheduled tasks about spring-boot HOT 4 CLOSED

I'm not sure I understand the use case here.

3. For some of them, we first check if they are on pause or not (pause is triggered by an external event) and we only want an observation (and sub observations) if it's not on pause

How would you detect that a scheduled method would be on pause? What do you mean by that? Would it require the execution to be ongoing?

Then, I tried the following

All the solutions you've described could be implemented with an ObservationPredicate that looks at the observation context and checks the ScheduledTaskObservationContext#getMethod() for custom annotations. I don't think you would need to override any Spring Boot configuration nor implement your own ScheduledAnnotationBeanPostProcessor.

I'm probably missing something here.

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Hi @bclozel

How would you detect that a scheduled method would be on pause? What do you mean by that? Would it require the execution to be ongoing?

I have some scheduled tasks that are triggered frequently, but can decide by themselves to be on pause until a given time depending on some conditions.
For example, one scheduled task is used to purge data older than 30 days. Each time it's triggered, it retrieves the oldest data and purge it if it's older than 30 days. If it's not, then it decides to be on pause until this oldest data is 30 days old. That's just an example.

I'm probably missing something here.

Well, the problem is with children spans : if the ObservationPredicate says false, a NOOP observation is created and becomes the current observation. If the code called by the scheduled task creates also an observation, as its parent span is a NOOP, it will also be a NOOP. That's why it works for behavior 2, the scheduled task and children spans are NOOP. For behavior 3, I want children spans to be actual spans. With the ObservationPredicate, I can't have behavior 2 and behavior 3 depending on the use case.

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I see, thanks for the feedback.

So it sounds like you would like to change the active/noop status of an observation after it's been created.

Unfortunately, I don't think there is anything we can do in the Spring Framework @Scheduled instrumentation or in the Spring Boot auto-configuration. Please see this Micrometer issue (and especially the related ones) as I think this is really a Micrometer concern.

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Some additional thoughts.

The Observation API is one of the strengths of Micrometer. One can instrument apps and libraries for metrics, traces or both without introducing specific dependencies. Micrometer uses observation handlers that listen for the lifecycle of observations and turn them into metrics and traces. In this case, starting an observation has side-effects like starting to record a metric, adding headers to messages for tracing, and more. "Cancelling" an observation after it has started is challenging and would probably require specific checks that would hurt performance for instrumentations.

In your case, I understand that you probably don't want to record metrics for "paused jobs" as they're very short lived and are probably skewing numbers. For this, I think you could maybe let the observation be recorded, but add metadata to the observation context stating that it's been paused. This way, you can build your metrics dashboard using this dimension and avoid conflating paused/unpaused jobs.

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