8210280: Unnecessary reallocation when invoking HashMap.putAll()

Co-authored-by: Michal Vala <mvala@redhat.com>
Co-authored-by: Martin Buchholz <martinrb@google.com>
Reviewed-by: martin, mvala, igerasim, chegar, rriggs

src/java.base/share/classes/java/util/HashMap.java

@@ -501,9 +501,14 @@ public class HashMap<K,V> extends AbstractMap<K,V>
                          (int)ft : MAXIMUM_CAPACITY);
                 if (t > threshold)
                     threshold = tableSizeFor(t);
+            } else {
+                // Because of linked-list bucket constraints, we cannot
+                // expand all at once, but can reduce total resize
+                // effort by repeated doubling now vs later
+                while (s > threshold && table.length < MAXIMUM_CAPACITY)
+                    resize();
             }
-            else if (s > threshold)
-                resize();
+
             for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
                 K key = e.getKey();
                 V value = e.getValue();