MetricsFilter may create an unbounded number of metrics for requests with a templated URI that are not handled by Spring MVC

[heroicefforts]

The MetricsFilter is unsuitable for REST microservices that are backing a large number of entities. In our case, it was trying to generate gauges and counters for /widget/1 to /widget/60000000. It eventually soaks the heap and causes the server to slow to a crawl as it spends most of its CPU cycles in GC. There should be a big red "caveat" bubble in the documentation that details this scenario.

Ideally, a Spring MVC controller metrics controller should be implemented that works similar to the DropWizard Jersey 2 implementation (plus some RequestMapping introspection), then the MetricsFilter could be disabled by default.

[wilkinsona]

The behaviour you've described isn't intended, and it doesn't match what's tested.

In one of the tests there's a request mapping like this: @RequestMapping("templateVarTest/{someVariable}"). It's called with /templateVarTest/foo which results in status.200.templateVarTest.someVariable and response.templateVarTest.someVariable being updated. As you can see, it's the name of the variable in the request mapping rather than the value in the request URI that's used.

Can you please provide a sample or testcase that illustrates the behaviour you have described?

[heroicefforts]

Then, perhaps, it is a consequence of using Jersey with SpringBoot (don't get me started on why we're using both...):

@GET
@Path("/parent/{pid}/child/{cid}")
@Produces("application/json")
@Timed(name="child.reads")
public Response readChild(@Context UriInfo uriInfo, @PathParam("pid") String parentId,
        @PathParam("cid") String childId) { ... } 

[wilkinsona]

Thanks. That'll be it. We need to use Jersey's equivalent of Spring MVC's best matching pattern attribute (assuming it has such a thing).

[beckje01]

So does that mean https://github.com/spring-projects/spring-boot/blob/master/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/MetricsFilter.java#L104 needs to become pluggable?

[wilkinsona]

@beckje01 No, I don't think so. It think it's something similar to this that we need to do for Jersey.

[beckje01]

Ok so we just need to make sure things are putting that attribute in, this same issue effect Grails 3 as well. So that way anything built on boot the metrics will work for assuming the attribute is set.

[jbellmann]

Hi,
maybe this snippet could help here?