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HHH-13660 Reduce allocation costs of IdentityMaps used by ResultSetProcessingContextImpl

This commit is contained in:
Sanne Grinovero 2019-10-09 10:24:04 +01:00
parent d6376834a7
commit 9dd6b8439b
1 changed files with 13 additions and 4 deletions
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17
hibernate-core/src/main/java/org/hibernate/loader/plan/exec/process/internal/ResultSetProcessingContextImpl.java
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@ -58,6 +58,8 @@ public class ResultSetProcessingContextImpl implements ResultSetProcessingContex
private List<HydratedEntityRegistration> hydratedEntityRegistrationList;
private int nRowsRead = 0;
private Map<EntityReference,EntityReferenceProcessingState> identifierResolutionContextMap;
/**
* Builds a ResultSetProcessingContextImpl
*
@ -137,15 +139,22 @@ public class ResultSetProcessingContextImpl implements ResultSetProcessingContex
return LockMode.NONE;
}
private Map<EntityReference,EntityReferenceProcessingState> identifierResolutionContextMap;
@Override
public EntityReferenceProcessingState getProcessingState(final EntityReference entityReference) {
EntityReferenceProcessingState context;
if ( identifierResolutionContextMap == null ) {
identifierResolutionContextMap = new IdentityHashMap<>();
//The default expected size of IdentityHashMap is 21, which is likely to allocate larger arrays than what is typically necessary.
//Reducing to 5, as a reasonable estimate for typical use: any larger query can better justify the need to resize,
//while single loads shouldn't pay such an high cost.
//This can save a lot of memory as it reduces the internal table of IdentityHashMap from a 64 slot array, to 16 slots:
//that's a 75% memory cost reduction for usage patterns which do many individual loads.
identifierResolutionContextMap = new IdentityHashMap<>(5);
context = null;
}
else {
context = identifierResolutionContextMap.get( entityReference );
}
EntityReferenceProcessingState context = identifierResolutionContextMap.get( entityReference );
if ( context == null ) {
context = new EntityReferenceProcessingState() {
private boolean wasMissingIdentifier;