--- jsr166/src/test/tck/ConcurrentHashMap8Test.java	2015/04/25 04:55:30	1.28
+++ jsr166/src/test/tck/ConcurrentHashMap8Test.java	2016/10/15 18:51:12	1.32
@@ -11,12 +11,13 @@ import static java.util.Spliterator.NONN
 import java.util.AbstractMap;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.Spliterator;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.LongAdder;
 import java.util.function.BiFunction;
@@ -406,7 +407,7 @@ public class ConcurrentHashMap8Test exte
         Integer[] elements = new Integer[size];
         for (int i = 0; i < size; i++)
             elements[i] = i;
-        Collections.shuffle(Arrays.asList(elements));
+        shuffle(elements);
         Collection<Integer> full = populatedSet(elements);
 
         Iterator it = full.iterator();
@@ -496,7 +497,7 @@ public class ConcurrentHashMap8Test exte
         Integer[] elements = new Integer[size];
         for (int i = 0; i < size; i++)
             elements[i] = i;
-        Collections.shuffle(Arrays.asList(elements));
+        shuffle(elements);
         Collection<Integer> full = populatedSet(elements);
 
         assertTrue(Arrays.asList(elements).containsAll(Arrays.asList(full.toArray())));
@@ -516,7 +517,7 @@ public class ConcurrentHashMap8Test exte
         a = new Integer[0];
         assertSame(a, empty.toArray(a));
 
-        a = new Integer[size/2];
+        a = new Integer[size / 2];
         Arrays.fill(a, 42);
         assertSame(a, empty.toArray(a));
         assertNull(a[0]);
@@ -526,7 +527,7 @@ public class ConcurrentHashMap8Test exte
         Integer[] elements = new Integer[size];
         for (int i = 0; i < size; i++)
             elements[i] = i;
-        Collections.shuffle(Arrays.asList(elements));
+        shuffle(elements);
         Collection<Integer> full = populatedSet(elements);
 
         Arrays.fill(a, 42);
@@ -1088,4 +1089,30 @@ public class ConcurrentHashMap8Test exte
         assertNull(r);
     }
 
+    /**
+     * Tests performance of computeIfAbsent when the element is present.
+     * See JDK-8161372
+     * ant -Djsr166.tckTestClass=ConcurrentHashMapTest -Djsr166.methodFilter=testcomputeIfAbsent_performance -Djsr166.expensiveTests=true tck
+     */
+    public void testcomputeIfAbsent_performance() {
+        final int mapSize = 20;
+        final int iterations = expensiveTests ? (1 << 23) : mapSize * 2;
+        final int threads = expensiveTests ? 10 : 2;
+        final ConcurrentHashMap<Integer, Integer> map = new ConcurrentHashMap<>();
+        for (int i = 0; i < mapSize; i++)
+            map.put(i, i);
+        final ExecutorService pool = Executors.newFixedThreadPool(2);
+        try (PoolCleaner cleaner = cleaner(pool)) {
+            Runnable r = new CheckedRunnable() {
+                public void realRun() {
+                    int result = 0;
+                    for (int i = 0; i < iterations; i++)
+                        result += map.computeIfAbsent(i % mapSize, (k) -> k + k);
+                    if (result == -42) throw new Error();
+                }};
+            for (int i = 0; i < threads; i++)
+                pool.execute(r);
+        }
+    }
+
 }