Non-working MapPerformanceJMH.java

To try to figure out how to get it to work.

Author: Bruce Eckel

threads/HorseRace.java

@@ -42,7 +42,7 @@ public String tracks() {
 }
 
 public class HorseRace {
-  static final int FINISH_LINE = 75;
+  static final int FINISH_LINE = 60;
   private List<Horse> horses = new ArrayList<>();
   private ExecutorService exec =
     Executors.newCachedThreadPool();
@@ -90,7 +90,7 @@ public static void main(String[] args) {
 }
 /* Output: (First and Last 18 Lines)
 ===========================================================
-================
+=
 0
 **1
 2
@@ -99,47 +99,38 @@ public static void main(String[] args) {
 *5
 **6
 ===========================================================
-================
+=
 **0
 ***1
-**2
-**3
-***4
-*5
+*2
+*3
+****4
+**5
 ****6
 ===========================================================
-================
+=
 **0
 ...________...________...________...________...
-***********************************************************
-*******6
+**********************************************6
 ===========================================================
-================
-***********************************************************
-**********0
-***********************************************************
-**********1
-***********************************************************
-***********2
+=
+**************************************************0
+*************************************************1
+*********************************************2
 ***********************************************************
-***************3
-********************************************************4
-*********************************************************5
-***********************************************************
-*******6
+3
+*****************************************************4
+*****************************************************5
+***********************************************6
 ===========================================================
-================
-***********************************************************
-***********0
-***********************************************************
-**********1
+=
+****************************************************0
+*************************************************1
+***********************************************2
 ***********************************************************
-************2
-***********************************************************
-*****************3
-*********************************************************4
-**********************************************************5
-***********************************************************
-*******6
+*3
+*******************************************************4
+*******************************************************5
+***********************************************6
 Horse 3 won!
 */

understandingcollections/jmhtests/MapPerformanceJMH.java

@@ -0,0 +1,66 @@
+// understandingcollections/jmhtests/MapPerformanceJMH.java
+// (c)2016 MindView LLC: see Copyright.txt
+// We make no guarantees that this code is fit for any purpose.
+// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
+// Demonstrates performance differences in Maps
+package understandingcollections.jmhtests;
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.infra.Blackhole;
+import java.util.*;
+
+@State(Scope.Thread)
+public class MapPerformanceJMH {
+  private Map<Integer, Integer> map;
+
+  @Param({"hashmap", "treemap"})
+  private String type;
+
+  private int begin;
+  private int end;
+
+  @Setup
+  public void setup() {
+    if (type.equals("hashmap")) {
+      map = new HashMap<Integer, Integer>();
+    } else if (type.equals("treemap")) {
+      map = new TreeMap<Integer, Integer>();
+    } else {
+      throw new IllegalStateException("Unknown type: " + type);
+    }
+
+    begin = 1;
+    end = 256;
+    for (int i = begin; i < end; i++) {
+      map.put(i, i);
+    }
+  }
+
+  @Benchmark
+  public void get(Blackhole bh) {
+    for (int i = begin; i < end; i++) {
+      bh.consume(map.get(i));
+    }
+  }
+
+// These are incomplete placeholders from the
+// original MapPerformance.jaava:
+/*  @Benchmark
+  int put() {
+    for(int i = 0; i < loops; i++) {
+      map.clear();
+      for(int j = 0; j < size; j++)
+        map.put(j, j);
+    }
+    return loops * size;
+  }*/
+
+/*  @Benchmark
+  int iterate() {
+    for(int i = 0; i < loops; i ++) {
+      Iterator it = map.entrySet().iterator();
+      while(it.hasNext())
+        it.next();
+    }
+  }*/
+
+}