generate random lists for benchmarks

turns out this changes the performance characteristics dramatically

primitiveCollections/src/jmh/java/org/lucares/collections/BenchmarkMultiwayMerge.java

@@ -2,6 +2,7 @@ package org.lucares.collections;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 import java.util.stream.LongStream;
 
@@ -22,25 +23,34 @@ import org.openjdk.jmh.annotations.Warmup;
 @BenchmarkMode(Mode.Throughput)
 @Warmup(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
 @Measurement(iterations = 5, time = 500, timeUnit = TimeUnit.MILLISECONDS)
-@Fork(3)
+@Fork(2)
 public class BenchmarkMultiwayMerge {
 
-	@Param({ "10000"/*, "20000" */})
+	@Param({ "10000" , "20000"  })
 	private int values;
 
-	@Param({/*"3","5",*/"10"})
+	@Param({  "3","5", "10","20" })
 	private int numLists;
 
+	@Param({ "true" })
+	private boolean random;
 
 	private List<LongList> longSorted = null;
 
 	@Setup
 	public void setup() throws Exception {
+		ThreadLocalRandom rng = ThreadLocalRandom.current();
 		longSorted = new ArrayList<>();
-		for(int i = 0; i < numLists; i++) {
-			LongList list = LongList.of();
-			LongStream.range(0, values).forEachOrdered(list::add);
+		for (int i = 0; i < numLists; i++) {
+			LongList list = new LongList(values);
+			if (random) {
+				for (int j = 0; j < values; j++) {
+					list.add(rng.nextLong());
+				}
 				list.sort();
+			} else {
+				LongStream.range(0, values).forEachOrdered(list::add);
+			}
 			longSorted.add(list);
 		}
 	}
@@ -56,7 +66,7 @@ public class BenchmarkMultiwayMerge {
 		LongList.union(longSorted);
 	}
 
-	//@Benchmark
+	@Benchmark
 	public void testUnionSortedLists_TwowayMergeImplementation() throws Exception {
 
 		twowayMerge(longSorted);
@@ -64,7 +74,7 @@ public class BenchmarkMultiwayMerge {
 
 	private void twowayMerge(List<LongList> longLists) {
 		LongList result = longLists.get(0);
-		for(int i =1; i < longLists.size(); i++) {
+		for (int i = 1; i < longLists.size(); i++) {
 			result = LongList.union(result, longLists.get(i));
 		}
 	}
@@ -72,12 +82,24 @@ public class BenchmarkMultiwayMerge {
 	public static void main(String[] args) throws Exception {
 		System.out.println("\n\n----------------\nstart");
 		// -XX:+PrintCompilation
-		for (int i = 0; i < 200; i++) {
+
+		if (args != null) {
 			BenchmarkMultiwayMerge benchmark = new BenchmarkMultiwayMerge();
+			benchmark.numLists = 10;
+			benchmark.values = 10000;
 			benchmark.setup();
-			//System.out.println("\n\n----------------\n"+i);
-			for (int j = 0; j < 100000; j++) {
 			benchmark.testUnionSortedLists_MultiwayMerge();
+		} else {
+			for (int i = 0; i < 8; i++) {
+				BenchmarkMultiwayMerge benchmark = new BenchmarkMultiwayMerge();
+				benchmark.numLists = 10;
+				benchmark.values = 10000;
+				benchmark.setup();
+				System.out.println("\n\n----------------\n" + i);
+				for (int j = 0; j < 1000; j++) {
+					// benchmark.testUnionSortedLists_MultiwayMerge();
+					benchmark.testUnionSortedLists_TwowayMergeImplementation();
+				}
 			}
 		}
 		System.out.println("done");