Failed to bind as java.util.concurrent.ThreadPerTaskExecutor is unsupported.

[loicmathieu]

Describe the bug
Micrometer ExecutorServiceMetrics class logs a warning Failed to bind as java.util.concurrent.ThreadPerTaskExecutor is unsupported. when runs in Java 21.

Environment

• Micrometer version: 1.12.2
• Micrometer registry: prometheus
• OS: Ubuntu 23.10
• Java version: 21

Expected behavior
No warning logs should be visible in the console.

[loicmathieu]

I just noticed there is a second log just after that seems to be also link to Java 21: Failed to bind as java.util.concurrent.Executors$AutoShutdownDelegatedExecutorService is unsupported.

[dozsa]

Ran into the same issue. Seems that the Java 21 ThreadPerTaskExecutor class is not supported by ExecutorServiceMetrics. You can see that in its bindTo method. So this will be an enhancement.

[shakuzen]

Which executor metrics specifically are you interested in with a ThreadPerTaskExecutor?

[loicmathieu]

@shakuzen no idea, I just want this warning to disappear and Micrometer to work as usual.

[shakuzen]

What do you mean by work as usual? The log message is making you aware something is trying to monitor an ExecutorService that is not supported. There will be no corresponding metrics but nothing is broken, per se. If you don't want the warning log, don't call ExecutorServiceMetrics.monitor with something not supported. If we didn't log anything in the case of trying to bind to a ThreadPerTaskExecutor, users might be confused why there are no metrics.

Are you configuring this yourself or is some library/framework trying to do this? If the latter, probably that library/framework should be updated to not do this with ThreadPerTaskExecutor until/unless it is supported.

[loicmathieu]

I'm using Micronaut.
I'll report the message at their side.

[dozsa]

By reading the source for both ExecutorServiceMetrics and ThreadPerTaskExecutor I think the only metric it could capture is ThreadPerTaskExecutor.threadCount() which would map to executor.active.

[vad3x]

It seems it's been fixed here: micronaut-projects/micronaut-micrometer#679

[loicmathieu]

OK, let's close it.
Thanks @vad3x

[shakuzen]

@angulito that's not really related to this issue. It would have been better to comment on that pull request. I've left a review on it now.