datasource-micrometer is causing application to halt from spring boot 3.4.1

[rajadilipkolli]

I have this application with works fine with autoconfiguration of datasource-micrometer till 3.4.0 , the moment I have upgraded to 3.4.1 it is halting and never proceeding further

In src/test/java/com/example/learning/common/AbstractIntegrationTest.java I have added a property to turn on and off for replicating the issue. When autoconfiguration is disabled as default is on, everything works as expected.

[ttddyy]

@rajadilipkolli Thanks for the report and repro.

I debugged it and found this is where the hang happens when running DataSourceObservationListener.

observationRegistrySupplier.get() is a supplier that lazily gets an ObservationRegistry bean.
The actual supplier is a lambda from DataSourceObservationAutoConfiguration#L99 which is an ObjectProvider<ObservationRegistry>.

The DataSourceObservationListener is called while spring is creating a LocalContainerEntityManagerFactoryBean bean in a separate thread and trying to access the database to obtain metadata - AbstractEntityManagerFactoryBean#L397

I suspect there is some locks in spring trying to retrieve a bean via ObjectProvider while another bean(LocalContainerEntityManagerFactoryBean) is in creation.

I need to investigate more details but this is so far what I found.

[ttddyy]

@rajadilipkolli I debugged the root cause and filed spring-projects/spring-framework#34247 where I detailed the deadlock scenario. I also created #56 to improve datasource-micrometer.

To workaround/solve the problem on your app, you need to change the spring.data.jpa.repositories.bootstrap-mode property to default, so that EntityManager and all related beans are created on the main thread.

Since I have created #56, I am closing this issue.

Thanks for your report!!

[ttddyy]

It'll be fixed in Spring Framework 6.2.2 which will be used by Boot 3.4.2.