[hibernate-issues] [JIRA] (HHH-16218) Natural id cache is extremely slow for entities with compound natural id

Sylvain Dusart ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=63f6394... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiZTQ4YzI3ZDQ1... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-16218?atlOrigin=eyJpIjoiZTQ4Yz... ) HHH-16218 ( https://hibernate.atlassian.net/browse/HHH-16218?atlOrigin=eyJpIjoiZTQ4Yz... ) Natural id cache is extremely slow for entities with compound natural id ( https://hibernate.atlassian.net/browse/HHH-16218?atlOrigin=eyJpIjoiZTQ4Yz... ) Change By: Sylvain Dusart ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=63f6394... ) Hibernate maintains a cache for id<->naturalId correspondances (pkToNaturalIdMap and naturalIdToPkMap maps in org.hibernate.engine.internal.NaturalIdResolutionsImpl.EntityResolutions#cache). This cache is updated after creations and loads (at least, I did not test other use-cases) . In the maps, the natural id is encapsulated in a ResolutionImpl instance and the hashcode is computed in the constructor : {code:java}final int prime = 31; int hashCodeCalculation = 1; hashCodeCalculation = prime * hashCodeCalculation + entityDescriptor.hashCode(); hashCodeCalculation = prime * hashCodeCalculation + entityDescriptor.getNaturalIdMapping().calculateHashCode( naturalIdValue, persistenceContext.getSession() );{code} For entities with a simple natural id, entityDescriptor.getNaturalIdMapping() is an instance of SimpleNaturalIdMapping with this calculateHashCode method : {code:java}@Override public int calculateHashCode(Object value) { //noinspection unchecked return value == null ? 0 : ( (JavaType<Object>) getJavaType() ).extractHashCode( value ); }{code} For entities with a compound natural id, entityDescriptor.getNaturalIdMapping() is an instance of CompoundNaturalIdMapping with this calculateHashCode method : {code:java}@Override public int calculateHashCode(Object value) { return 0; }{code} As a consequence, for a given entity with a compound natural id, the hashcodes of all ResolutionImpl objects used as keys in naturalIdToPkMap are the same, which creates collisions and consumes a lot of cpu cycles. The calculateHashCode method in CompoundNaturalIdMapping should be something like {code:java}@Override public int calculateHashCode(Object value) { return Arrays.hashCode((Object[]) value); }{code} to align with the areEqual method. The attached test case creates 20000 objects in database then re-reads these objects. It is done for two entity classes : EntityWithSimpleNaturalId and EntityWithCompoundNaturalId. Logs before correction modification : {code:java}16:33:31,782  INFO CompoundNaturalIdCacheTest:64 - Starting creations 16:33:53,745  INFO CompoundNaturalIdCacheTest:74 - Persisted 20000 EntityWithCompoundNaturalId objects, duration=21957ms 16:33:53,906  INFO CompoundNaturalIdCacheTest:83 - Persisted 20000 EntityWithSimpleNaturalId objects, duration=160ms 16:33:55,140  INFO CompoundNaturalIdCacheTest:115 - Loading at most 20000  instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithCompoundNaturalId 16:34:12,915  INFO CompoundNaturalIdCacheTest:123 - Loaded 20000 instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithCompoundNaturalId, duration=17777ms 16:34:12,921  INFO CompoundNaturalIdCacheTest:115 - Loading at most 20000  instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithSimpleNaturalId 16:34:13,021  INFO CompoundNaturalIdCacheTest:123 - Loaded 20000 instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithSimpleNaturalId, duration=99ms{code} Logs after correction modification : {code:java}16:35:37,950  INFO CompoundNaturalIdCacheTest:64 - Starting creations 16:35:38,247  INFO CompoundNaturalIdCacheTest:74 - Persisted 20000 EntityWithCompoundNaturalId objects, duration=292ms 16:35:38,368  INFO CompoundNaturalIdCacheTest:83 - Persisted 20000 EntityWithSimpleNaturalId objects, duration=119ms 16:35:39,679  INFO CompoundNaturalIdCacheTest:115 - Loading at most 20000  instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithCompoundNaturalId 16:35:40,096  INFO CompoundNaturalIdCacheTest:123 - Loaded 20000 instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithCompoundNaturalId, duration=418ms 16:35:40,103  INFO CompoundNaturalIdCacheTest:115 - Loading at most 20000  instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithSimpleNaturalId 16:35:40,232  INFO CompoundNaturalIdCacheTest:123 - Loaded 20000 instances of class org.hibernate.orm.test.mapping.naturalid.compound.CompoundNaturalIdCacheTest$EntityWithSimpleNaturalId, duration=129ms{code} ( https://hibernate.atlassian.net/browse/HHH-16218#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16218#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! 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