Improved profiling section

validating/BadMicroBenchmark.java

@@ -5,7 +5,7 @@
 import java.util.*;
 
 public class BadMicroBenchmark {
-  static final int SIZE = 20_000_000;
+  static final int SIZE = 250_000_000;
   public static void main(String[] args) {
     long[] la = new long[SIZE];
     System.out.print("setAll: ");
@@ -15,6 +15,6 @@ public class BadMicroBenchmark {
   }
 }
 /* Output:
-setAll: 75
+setAll: 272
-parallelSetAll: 110
+parallelSetAll: 301
 */

validating/BadMicroBenchmark2.java

@@ -2,20 +2,33 @@
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://OnJava8.com for more book information.
-// Reversing the test order
+// Relying on a common resource
 import java.util.*;
 
 public class BadMicroBenchmark2 {
-  static final int SIZE = 20_000_000;
+  // SIZE reduced to make it run faster:
+  static final int SIZE = 5_000_000;
   public static void main(String[] args) {
     long[] la = new long[SIZE];
+    Random r = new Random();
     System.out.print("parallelSetAll: ");
-    Time.it(() -> Arrays.parallelSetAll(la, n -> n));
+    Time.it(() ->
+      Arrays.parallelSetAll(la, n -> r.nextLong()));
     System.out.print("setAll: ");
-    Time.it(() -> Arrays.setAll(la, n -> n));
+    Time.it(() ->
+      Arrays.setAll(la, n -> r.nextLong()));
+    SplittableRandom sr = new SplittableRandom();
+    System.out.print("parallelSetAll: ");
+    Time.it(() ->
+      Arrays.parallelSetAll(la, n -> sr.nextLong()));
+    System.out.print("setAll: ");
+    Time.it(() ->
+      Arrays.setAll(la, n -> sr.nextLong()));
   }
 }
 /* Output:
-parallelSetAll: 68
+parallelSetAll: 1360
-setAll: 196
+setAll: 125
+parallelSetAll: 75
+setAll: 17
 */

validating/BadMicroBenchmark3.java

@@ -1,33 +0,0 @@
-// validating/BadMicroBenchmark3.java
-// (c)2016 MindView LLC: see Copyright.txt
-// We make no guarantees that this code is fit for any purpose.
-// Visit http://OnJava8.com for more book information.
-// Relying on a common resource
-import java.util.*;
-
-public class BadMicroBenchmark3 {
-  static final int SIZE = 20_000_000;
-  public static void main(String[] args) {
-    long[] la = new long[SIZE];
-    Random r = new Random();
-    System.out.print("parallelSetAll: ");
-    Time.it(() ->
-      Arrays.parallelSetAll(la, n -> r.nextLong()));
-    System.out.print("setAll: ");
-    Time.it(() ->
-      Arrays.setAll(la, n -> r.nextLong()));
-    SplittableRandom sr = new SplittableRandom();
-    System.out.print("parallelSetAll: ");
-    Time.it(() ->
-      Arrays.parallelSetAll(la, n -> sr.nextLong()));
-    System.out.print("setAll: ");
-    Time.it(() ->
-      Arrays.setAll(la, n -> sr.nextLong()));
-  }
-}
-/* Output:
-parallelSetAll: 4540
-setAll: 1540
-parallelSetAll: 398
-setAll: 739
-*/

validating/jmh/JMH1.java

@@ -1,17 +1,24 @@
-// validating/jmh/ParallelSetAll.java
+// validating/jmh/JMH1.java
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://OnJava8.com for more book information.
 package validating.jmh;
 import java.util.*;
 import org.openjdk.jmh.annotations.*;
+import java.util.concurrent.TimeUnit;
 
 @State(Scope.Thread)
-public class ParallelSetAll {
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MICROSECONDS)
+// Increase these three for more accuracy:
+@Warmup(iterations = 5)
+@Measurement(iterations = 5)
+@Fork(1)
+public class JMH1 {
   private long[] la;
   @Setup
   public void setup() {
-    la = new long[20_000_000];
+    la = new long[250_000_000];
   }
   @Benchmark
   public void setAll() {

validating/jmh/JMH2.java

@@ -1,20 +1,37 @@
-// validating/jmh/ParallelSetAllBetter.java
+// validating/jmh/JMH2.java
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://OnJava8.com for more book information.
 package validating.jmh;
 import java.util.*;
 import org.openjdk.jmh.annotations.*;
+import java.util.concurrent.TimeUnit;
 
 @State(Scope.Thread)
-public class ParallelSetAllBetter {
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@Warmup(iterations = 5)
+@Measurement(iterations = 5)
+@Fork(1)
+public class JMH2 {
   private long[] la;
-  @Param({"1", "100", "10000", "1000000", "20000000"})
+  @Param({
-  int count;
+    "1",
+    "10",
+    "100",
+    "1000",
+    "10000",
+    "100000",
+    "1000000",
+    "10000000",
+    "100000000",
+    "250000000"
+  })
+  int size;
 
   @Setup
   public void setup() {
-    la = new long[count];
+    la = new long[size];
   }
   @Benchmark
   public void setAll() {

validating/jmh/JMH3.java

@@ -0,0 +1,48 @@
+// validating/jmh/JMH3.java
+// (c)2016 MindView LLC: see Copyright.txt
+// We make no guarantees that this code is fit for any purpose.
+// Visit http://OnJava8.com for more book information.
+package validating.jmh;
+import java.util.*;
+import org.openjdk.jmh.annotations.*;
+import java.util.concurrent.TimeUnit;
+
+@State(Scope.Thread)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@Warmup(iterations = 5)
+@Measurement(iterations = 5)
+@Fork(1)
+public class JMH3 {
+  private long[] la;
+  @Param({
+    "1",
+    "10",
+    "100",
+    "1000",
+    "10000",
+    "100000",
+    "1000000",
+    "10000000",
+    "100000000",
+    "250000000"
+  })
+  int size;
+
+  @Setup
+  public void setup() {
+    la = new long[size];
+  }
+  public static long f(long x) {
+    long divisor = x % 25 + 1;
+    return Long.divideUnsigned(x, divisor);
+  }
+  @Benchmark
+  public void setAll() {
+    Arrays.setAll(la, n -> f(n));
+  }
+  @Benchmark
+  public void parallelSetAll() {
+    Arrays.parallelSetAll(la, n -> f(n));
+  }
+}