Wired OOM error in my Spring Boot3 project

[hantsy]

In the spring boot 3 project, we got an OOM error which caused by the ClassGraph lib.

After searching the dependency tree, our SpringDoc lib depends on classgraph in its dependencies.

 java.lang.IllegalStateException: Failed to load ApplicationContext for [ReactiveWebMergedContextConfiguration@1bba692a testClass = io.etip.backend.rest.JobTitleControllerTest, locations = [], classes = [io.etip.backend.Application, io.etip.backend.rest.JobTitleControllerTest.TestConfig], contextInitializerClasses = [], activeProfiles = [], propertySourceLocations = [], propertySourceProperties = ["org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTestContextBootstrapper=true"], contextCustomizers = [MockkContextCustomizer(definitions=[[MockkDefinition@3df34748 name = [null], typeToMock = io.etip.backend.domain.business.repository.JobTitleRepository, extraInterfaces = set[[empty]], clear = AFTER], [MockkDefinition@5d2e5cfa name = [null], typeToMock = io.etip.backend.domain.service.StorageService, extraInterfaces = set[[empty]], clear = AFTER]]), org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory$DisableAutoConfigurationContextCustomizer@2cd388f5, org.springframework.boot.test.autoconfigure.actuate.observability.ObservabilityContextCustomizerFactory$DisableObservabilityContextCustomizer@9da1, org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizer@4109f44, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@d83272ea, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@56846330, [ImportsContextCustomizer@47e3076 key = [org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration, org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration, org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration, org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration, org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration, org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration, org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration, org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration, org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration, org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration, org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration, org.springframework.boot.test.autoconfigure.web.reactive.WebTestClientAutoConfiguration]], org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@2091833, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@554188ac, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.context.SpringBootTestAnnotation@323d8803], contextLoader = org.springframework.boot.test.context.SpringBootContextLoader, parent = null]

      Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'webHandler' defined in class path resource [org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfiguration$EnableWebFluxConfiguration.class]: Error creating bean with name 'resourceHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfiguration$EnableWebFluxConfiguration.class]: Failed to instantiate [org.springframework.web.reactive.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception with message: Uncaught exception during scan

      Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'resourceHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfiguration$EnableWebFluxConfiguration.class]: Failed to instantiate [org.springframework.web.reactive.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception with message: Uncaught exception during scan

      Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.reactive.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception with message: Uncaught exception during scan

      Caused by: io.github.classgraph.ClassGraphException: Uncaught exception during scan

      Caused by: java.lang.OutOfMemoryError: Java heap space

[lukehutch]

If your library is indiscriminately scanning the entire classpath, and storing ClassInfo objects for every class encountered, then yes, ClassGraph can consume a large amount of RAM. The fix is probably to modify the library to scan the smallest set of classes possible.

[hantsy]

Personally, I do not care about the classgraph, it is just a dep of springdoc which I used in my project to produce Swagger UI/OpenAPI. But I am not sure why I encountered this issue.

Although I do not enabled spring doc in Spring default profile when running tests, it is 100% failed in my feature branch.

And I have just tried to remove spring-doc dep/config, worked again, and it also save 2 min to build the whole project.

Before this, I have tried to use a custom larger Github runner(4 core+ 16 G) and also increase the Gradle heap size to build the project, it is no help.

[lukehutch]

OK, well you need to file a bug with springdoc then, ClassGraph only scans what it is told to scan.