6933217: Huge arrays handled poorly in core libraries

Summary: Write overflow-conscious array resizing code
Reviewed-by: chegar

1 files changed, 30 insertions, 9 deletions

diff --git a/src/share/classes/java/util/Vector.java b/src/share/classes/java/util/Vector.java
index f70d36ee06..6fa6c84f8d 100644
--- a/src/share/classes/java/util/Vector.java
+++ b/src/share/classes/java/util/Vector.java
@@ -235,16 +235,37 @@ public class Vector<E>
      * @see #ensureCapacity(int)
      */
     private void ensureCapacityHelper(int minCapacity) {
+        // overflow-conscious code
+        if (minCapacity - elementData.length > 0)
+            grow(minCapacity);
+    }
+
+    /**
+     * The maximum size of array to allocate.
+     * Some VMs reserve some header words in an array.
+     * Attempts to allocate larger arrays may result in
+     * OutOfMemoryError: Requested array size exceeds VM limit
+     */
+    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
+
+    private void grow(int minCapacity) {
+        // overflow-conscious code
         int oldCapacity = elementData.length;
-        if (minCapacity > oldCapacity) {
-            Object[] oldData = elementData;
-            int newCapacity = (capacityIncrement > 0) ?
-                (oldCapacity + capacityIncrement) : (oldCapacity * 2);
-            if (newCapacity < minCapacity) {
-                newCapacity = minCapacity;
-            }
-            elementData = Arrays.copyOf(elementData, newCapacity);
-        }
+        int newCapacity = oldCapacity + ((capacityIncrement > 0) ?
+                                         capacityIncrement : oldCapacity);
+        if (newCapacity - minCapacity < 0)
+            newCapacity = minCapacity;
+        if (newCapacity - MAX_ARRAY_SIZE > 0)
+            newCapacity = hugeCapacity(minCapacity);
+        elementData = Arrays.copyOf(elementData, newCapacity);
+    }
+
+    private static int hugeCapacity(int minCapacity) {
+        if (minCapacity < 0) // overflow
+            throw new OutOfMemoryError();
+        return (minCapacity > MAX_ARRAY_SIZE) ?
+            Integer.MAX_VALUE :
+            MAX_ARRAY_SIZE;
     }
 
     /**