Issue 1957: Presize HashMap allocations in UnitOfWorkImpl

add initial size to map creation where expected size is known or can be estimated Signed-off-by: Patrick Schmitt <[email protected]>
eclipse-ee4j · Oct 6, 2023 · 7597856 · 7597856
1 parent 9ee7a29
commit 7597856
Showing 1 changed file with 11 additions and 7 deletions.
diff --git a/...clipse.persistence.core/src/org/eclipse/persistence/internal/sessions/UnitOfWorkImpl.java b/...clipse.persistence.core/src/org/eclipse/persistence/internal/sessions/UnitOfWorkImpl.java
@@ -50,6 +50,7 @@
 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;
@@ -708,8 +709,9 @@ 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();
 
@@ -785,7 +787,7 @@ 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);
@@ -806,8 +808,9 @@ 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);
                 }
@@ -5028,8 +5031,9 @@ protected void setNewObjectsCloneToOriginal(Map newObjects) {
       protected void setupPrimaryKeyToNewObjects() {
         primaryKeyToNewObjects = null;
         if (hasNewObjects()) {
-          primaryKeyToNewObjects = new HashMap<>();
-          getNewObjectsCloneToOriginal().forEach((object, o2) -> {
+            Map newObjects = getNewObjectsCloneToOriginal();
+            primaryKeyToNewObjects = new HashMap<>(newObjects.size());
+            newObjects.forEach((object, o2) -> {
             addNewObjectToPrimaryKeyToNewObjects(object);
           });
         }