Lazy dependency proxy does not populate bean dependencies

[BoykoAlex]

Start off with the latest spring-petclinic project based on Boot 2.3.x
Launch the app and see the JSON response for /actuator/beans
Search for OwnerController bean. This bean should depend on OwnerRepository and PetRepository. The JSON for the bean however is this:

        "ownerController": {
          "aliases": [],
          "scope": "singleton",
          "type": "org.springframework.samples.petclinic.owner.OwnerController",
          "resource": "file [/Users/aboyko/Documents/runtime-sts4/spring-petclinic/target/classes/org/springframework/samples/petclinic/owner/OwnerController.class]",
          "dependencies": []
        },

If spring-petclinic is switched to Boot 2.2.x then the dependencies are detected correctly:

        "ownerController": {
          "aliases": [],
          "scope": "singleton",
          "type": "org.springframework.samples.petclinic.owner.OwnerController",
          "resource": "file [/Users/aboyko/Documents/runtime-sts4/spring-petclinic/target/classes/org/springframework/samples/petclinic/owner/OwnerController.class]",
          "dependencies": [
            "ownerRepository",
            "visitRepository"
          ]
        },

Something is off in the framework as actuator simply calls org.springframework.beans.factory.config.ConfigurableBeanFactory.getDependenciesForBean(String)

Try this in the org.springframework.samples.petclinic.PetClinicApplication for the main method:

	public static void main(String[] args) {
		ConfigurableApplicationContext context = SpringApplication.run(PetClinicApplication.class, args);

		final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);

		final Runnable printDependnecies = new Runnable() {
			public void run() {
				String[] dependenciesForBean = context.getBeanFactory().getDependenciesForBean("ownerController");
				
				if (dependenciesForBean.length == 0) {
					System.out.println("no dependencies!!!");
				} else {
					System.out.println("Dependencies:");
					for (String dep : dependenciesForBean) {
						System.out.println(dep);
					}
					System.out.println();
				}
			}
		};

		scheduler.scheduleAtFixedRate(printDependnecies, 10, 10, TimeUnit.SECONDS);

	}

You'd see that there are no dependencies returned in the Boot 2.3.x case.

[snicoll]

Spring Boot 2.3 uses the same Spring Framework generation as Spring Boot 2.2. If you've debugged this, it would be nice to share the two Spring Framework versions that you've used.

[BoykoAlex]

Yes, it seems to be Spring 5.2.8.RELEASE in both cases. Should this be routed to Boot then?

[snicoll]

Thank you. I've reproduced the problem and it does not occur with Spring Boot 2.2.9.RELEASE indeed.

[snicoll]

It's interesting to see that the bean dependencies aren't available in the core BeanRegistry so I don't immediately see why it works with Spring Boot 2.2.9.RELEASE but does not with 2.3.2.RELEASE, given the same framework version is used.

[wilkinsona]

I think this is a Framework bug. The change in behaviour is due to the JPA repositories being lazy by default in Spring Boot 2.3. The repository dependencies are detected again if you set spring.data.jpa.repositories.bootstrap-mode=default. They're missing in the lazy case due to this logic in DefaultListableBeanFactory:

Object result = getAutowireCandidateResolver().getLazyResolutionProxyIfNecessary(
		descriptor, requestingBeanName);
if (result == null) {
	result = doResolveDependency(descriptor, requestingBeanName, autowiredBeanNames, typeConverter);
}
return result;

In the lazy case, result is non-null so autowiredBeanNames is never populated.

[snicoll]

Very nice detective work @wilkinsona!

@BoykoAlex you can workaround the problem in the meantime adding the following to application.properties:

spring.data.jpa.repositories.bootstrap-mode=default

[snicoll]

@jhoeller I've tentatively assigned 5.2.9.

[jhoeller]

This is more or less by design: Lazy proxy resolution doesn't know the actual targets upfront, and when it's eventually triggered, we cannot populate the original autowiredBeanNames mechanism anymore. We'd have to somehow mimic this in a separate code path within the lazy resolution proxy. I'll investigate this as an enhancement, possibly in 5.3 only though.

[jhoeller]

I got an implementation that's pretty straightforward, can easily make 5.2.9...

[jhoeller]

And since this is somewhat unintuitive indeed when switching to a lazy dependency proxy, I'll consider it a bug fix to backport...

[martinlippert]

Did this change make it into the 5.2.10 release? I am trying a pet clinic at Spring Boot 2.3.5 with Framework at 5.2.10 and the bean dependencies for the OwnerController (in our example above) are still empty. Will dive deeper tomorrow, but just wondering whether this fix made it into that version or not.

[jhoeller]

@martinlippert see the milestone above - it made it into 5.2.9 and got backported all the way down to 4.3.29. Not sure why it's not working for PetClinic with Boot 2.3.5 still. The fix here was only really addressing the core @Lazy problem, maybe some other difference between Boot 2.2 and 2.3 is involved as well?

[BoykoAlex]

I'm still seeing the same JSON for the ownerController bean with no dependencies and the main method snippet prints no bean dependencies (issue description)... Boot 2.3.5 and Spring 5.2.10. The workaround spring.data.jpa.repositories.bootstrap-mode=default still makes it work.
Seems like we may need to transfer this to boot now?

[jhoeller]

Please note that dependencies behind a lazy proxy are only going to be registered once the proxy is actually being initialized, that is, once a method invocation on the proxy led to the resolution of the target instance. That's the part that the fix addressed here.

[BoykoAlex]

@jhoeller Thanks for the last comment that clarified it really :-) Seems to all work as expected now. As soon as I add a new pet owner i see the clinic repo dependency. Think this is great :-)