Optimize ordered event listener performance [SPR-14642]

[spring-projects-issues]

Christoph Dreis opened SPR-14642 and commented

Hey,

while doing some loadtests in our project, I noticed that AnnotatedElementUtils.searchWithFindSemantics() or rather AnnotatedElementUtils.findMergedAnnotation() are consuming quite some CPU. It's even above HashMap.getNode(int, Object) in some tests, which I find quite precarious for such a utility class. It looks like this is especially true for using @Order somewhere in the application in combination with @EventListener functionality.

I was wondering if this could be improved in any way? Maybe by caching merged annotation lookups much like in AnnotationUtils. Or maybe by just caching the order in the ApplicationListener context.

!annotated_element_utils_jmc.jpg|thumbnail!

Cheers,
Christoph

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Affects: 4.3.2

Attachments:

• annotated_element_utils_jmc.jpg (483.01 kB)

Issue Links:

• ApplicationListener-like annotation for consuming application events [SPR-11622] #16245 ApplicationListener-like annotation for consuming application events
• Use AnnotatedElementUtils instead of AnnotationUtils wherever feasible [SPR-13440] #18020 Use AnnotatedElementUtils instead of AnnotationUtils wherever feasible

Referenced from: commits 58fa63f, 3b91dec

[spring-projects-issues]

Juergen Hoeller commented

Since findMergedAnnotation is indeed an expensive lookup call, we aim for caching the outcome in appropriate places. This is fortunately straightforward in the present case here: ApplicationListenerMethodAdapter initializes an order field on construction now, simply returning the value from getOrder().

[spring-projects-issues]

Christoph Dreis commented

Great. Saw your commit already. Just out of curiosity - are the ApplicationListenerMethodAdapter instances created only once at startup? Or are they created over and over again? The latter would be still quite intense for the new constructor behaviour, don't you think?

[spring-projects-issues]

Juergen Hoeller commented

EventListenerMethodProcessor creates one ApplicationListenerMethodAdapter per annotated method and registers the instance via ConfigurableApplicationContext.addApplicationListener directly, so we should be good here.

[spring-projects-issues]

Christoph Dreis commented

Perfect. Thanks again :-)

[spring-projects-issues]

Stéphane Nicoll commented

I second that!