When attempting to upgrade Spring Boot 2.5.7 to 2.6.0, the application tests running on Gitlab consistently run out of Heap Space. There were no issues before this upgrade.

OutOfMemoryError occurs during initialization of beans. Example:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1804)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1154)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:908)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:302)
    at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:120)
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:99)
    at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:124)
    at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:124)
    at org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener.postProcessFields(MockitoTestExecutionListener.java:110)
    at org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener.injectFields(MockitoTestExecutionListener.java:94)
    at org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener.prepareTestInstance(MockitoTestExecutionListener.java:61)
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:248)
    at org.springframework.test.context.junit.jupiter.SpringExtension.postProcessTestInstance(SpringExtension.java:138)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$8(ClassBasedTestDescriptor.java:363)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.executeAndMaskThrowable(ClassBasedTestDescriptor.java:368)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$9(ClassBasedTestDescriptor.java:363)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
    at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
    at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.StreamSpliterators$WrappingSpliterator.forEachRemaining(StreamSpliterators.java:310)
    at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:735)
    at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:734)
    at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeTestInstancePostProcessors(ClassBasedTestDescriptor.java:362)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$instantiateAndPostProcessTestInstance$6(ClassBasedTestDescriptor.java:283)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateAndPostProcessTestInstance(ClassBasedTestDescriptor.java:282)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$4(ClassBasedTestDescriptor.java:272)
    at java.base/java.util.Optional.orElseGet(Optional.java:364)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$5(ClassBasedTestDescriptor.java:271)
    at org.junit.jupiter.engine.execution.TestInstancesProvider.getTestInstances(TestInstancesProvider.java:31)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$prepare$0(TestMethodTestDescriptor.java:102)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:101)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:66)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$2(NodeTestTask.java:123)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:123)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:90)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:220)
    at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:188)
    at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:202)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:181)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:128)
    at org.apache.maven.surefire.junitplatform.JUnitPlatformProvider.invokeAllTests(JUnitPlatformProvider.java:150)
    at org.apache.maven.surefire.junitplatform.JUnitPlatformProvider.invoke(JUnitPlatformProvider.java:124)
    at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:384)
    at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:345)
    at org.apache.maven.surefire.booter.ForkedBooter.execute(ForkedBooter.java:126)
    at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:418)
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:421)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800)
    ... 84 common frames omitted
Caused by: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:123)
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:77)
    at org.hibernate.metamodel.internal.MetamodelImpl.initialize(MetamodelImpl.java:181)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:312)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:471)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1498)
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409)
    ... 88 common frames omitted
Caused by: org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer]
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:91)
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:116)
    at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:432)
    at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:613)
    at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:126)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:96)
    ... 96 common frames omitted
Caused by: java.lang.reflect.InvocationTargetException: null
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:88)
    ... 106 common frames omitted
Caused by: java.lang.IllegalArgumentException: Could not create type
    at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:155)
    at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:175)
    at org.hibernate.bytecode.internal.bytebuddy.ByteBuddyState.load(ByteBuddyState.java:178)
    at org.hibernate.bytecode.internal.bytebuddy.ByteBuddyState.loadProxy(ByteBuddyState.java:102)
    at org.hibernate.proxy.pojo.bytebuddy.ByteBuddyProxyHelper.buildProxy(ByteBuddyProxyHelper.java:55)
    at org.hibernate.proxy.pojo.bytebuddy.ByteBuddyProxyFactory.postInstantiate(ByteBuddyProxyFactory.java:61)
    at org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactory(PojoEntityTuplizer.java:102)
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:160)
    at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:53)
    ... 112 common frames omitted
Caused by: java.lang.OutOfMemoryError: Java heap space

Comment From: snicoll

@Bas83 we will need a bit more context than that to be able to help you. Please share a small sample that reproduces this error. You can do so by attaching a zip to this issue or sharing a link to a GitHub repository.

Comment From: Bas83

My apologies. It turned out this error is actually a combination of Spring 2.6.0 (and thus Hibernate 5.6.1) and Vlad's Hibernate-Types library hibernate-types-55 with version 2.14.0. I had deployed the latter first without issues, but then reverted when I found out it was intended for a newer Hibernate version than was included in Spring Boot 2.5.x. But the combination of these 2 is causing the OutOfMemoryError

Comment From: snicoll

Thanks for letting us know.