Presize HashMap allocations - backport from master (#2179)

* Issue #1957:: Presize HashMap allocations Signed-off-by: Patrick Schmitt <[email protected]>
eclipse-ee4j · Jun 25, 2024 · de0bdcd · de0bdcd
1 parent bc4e51b
commit de0bdcd
Showing 1 changed file with 10 additions and 6 deletions.
diff --git a/...sistence.core/src/main/java/org/eclipse/persistence/internal/sessions/UnitOfWorkImpl.java b/...sistence.core/src/main/java/org/eclipse/persistence/internal/sessions/UnitOfWorkImpl.java
@@ -51,6 +51,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.Vector;
+import java.util.stream.Collectors;
 
 import org.eclipse.persistence.annotations.CacheKeyType;
 import org.eclipse.persistence.config.ReferenceMode;
@@ -711,8 +712,9 @@ public UnitOfWorkChangeSet calculateChanges(Map registeredObjects, UnitOfWorkCha
 
         // Second calculate changes for all registered objects.
         Iterator objects = allObjects.keySet().iterator();
-        Map changedObjects = new IdentityHashMap();
-        Map visitedNodes = new IdentityHashMap();
+        int allObjectsSize = allObjects.size();
+        Map changedObjects = new IdentityHashMap(allObjectsSize);
+        Map visitedNodes = new IdentityHashMap(allObjectsSize);
         while (objects.hasNext()) {
             Object object = objects.next();
 
@@ -788,7 +790,7 @@ public UnitOfWorkChangeSet calculateChanges(Map registeredObjects, UnitOfWorkCha
 
         if (this.shouldDiscoverNewObjects && !changedObjects.isEmpty()) {
             // Third discover any new objects from the new or changed objects.
-            Map newObjects = new IdentityHashMap();
+            Map newObjects = new IdentityHashMap(changedObjects.size());
             // Bug 294259 -  Do not replace the existingObjects list
             // Iterate over the changed objects only.
             discoverUnregisteredNewObjects(changedObjects, newObjects, getUnregisteredExistingObjects(), visitedNodes);
@@ -809,8 +811,9 @@ public UnitOfWorkChangeSet calculateChanges(Map registeredObjects, UnitOfWorkCha
         // Remove any orphaned privately owned objects from the UnitOfWork and ChangeSets,
         // these are the objects remaining in the UnitOfWork privateOwnedObjects map
         if (hasPrivateOwnedObjects()) {
-            Map visitedObjects = new IdentityHashMap();
-            for (Set privateOwnedObjects : getPrivateOwnedObjects().values()) {
+            Collection<Set> values = getPrivateOwnedObjects().values();
+            Map visitedObjects = new IdentityHashMap(values.stream().collect(Collectors.summingInt(Set::size)));
+            for (Set privateOwnedObjects : values) {
                 for (Object objectToRemove : privateOwnedObjects) {
                     performRemovePrivateOwnedObjectFromChangeSet(objectToRemove, visitedObjects);
                 }
@@ -5029,7 +5032,8 @@ protected void setNewObjectsCloneToOriginal(Map newObjects) {
     protected void setupPrimaryKeyToNewObjects() {
         primaryKeyToNewObjects = null;
         if (hasNewObjects()) {
-            primaryKeyToNewObjects = new HashMap<>();
+            Map newObjects = getNewObjectsCloneToOriginal();
+            primaryKeyToNewObjects = new HashMap<>(newObjects.size());
             getNewObjectsCloneToOriginal().forEach((object, o2) -> {
                 addNewObjectToPrimaryKeyToNewObjects(object);
             });