Cannot use MicronautCaffeineCacheMetrics.monitor if there is caches section in application.yml

[markjfisher]

Expected Behavior

Upgrading an existing application from 2.x to 3.x should not fail when using both MicronautCaffeineCacheMetrics.monitor and a caches section (with cacheable functions in the application).

Actual Behaviour

Application fails to startup with error message:

Caused by: java.lang.IllegalArgumentException: Collector already registered that provides name: cache_eviction_weight
	at io.prometheus.client.CollectorRegistry.register(CollectorRegistry.java:54)
	at io.prometheus.client.Collector.register(Collector.java:175)
	at io.micrometer.prometheus.PrometheusMeterRegistry.lambda$applyToCollector$16(PrometheusMeterRegistry.java:479)

Steps To Reproduce

Download the example application provided, and run it.

Removing the "caches" entries from application.yml will stop it failing, but then doesn't provide statistics on the prometheus endpoint.

Environment Information

JDK 11, Linux various.

Example Application

https://github.com/markjfisher/mn-cache-graphql-monitor

Version

3.1.3

[markjfisher]

I raised this in gitter, but can't find a way of linking, but the search is from:"mark fisher" sent:[2021-11-04 TO 2021-11-05]

[jameskleeh]

Try changing OtherService to the following:

        CaffeineCacheMetrics.monitor(
            meterRegistry,
            cache,
            "graphQLDocumentCache"
        )

Note you have to use the com.github.benmanes.caffeine.cache imports

[markjfisher]

Excellent, I can now see the values in prometheus, and no errors.

cache_evictions_total{cache="graphQLDocumentCache",} 0.0
cache_evictions_total{cache="delivery-service",} 0.0

[jameskleeh]

@graemerocher Do you understand the need for https://github.com/micronaut-projects/micronaut-micrometer/blob/master/micrometer-core/src/main/java/io/micronaut/configuration/metrics/binder/cache/MicronautCaffeineCacheMetrics.java ? We relocate caffeine in core but I don't think any of the caches we create are setup for metrics

[graemerocher]

Should be deprecated and removed. Also the JAR jared version of caffeine should be removed IMO