introduction of fastutil.

VadereMeshing/pom.xml

@@ -44,6 +44,13 @@
             <version>${project.version}</version>
         </dependency>
 
+        <!-- fast collections especially for primitive data tyes -->
+        <dependency>
+            <groupId>it.unimi.dsi</groupId>
+            <artifactId>fastutil</artifactId>
+            <version>8.2.3</version>
+        </dependency>
+
         <!-- this is only to record some movies -->
         <dependency>
             <groupId>org.jcodec</groupId>

VadereMeshing/tests/org/vadere/util/TestFastUtil.java

+package org.vadere.util;
+
+import it.unimi.dsi.fastutil.doubles.DoubleArrayList;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.vadere.util.logging.Logger;
+
+import java.util.ArrayList;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+
+//https://www.retit.de/continuous-benchmarking-with-jmh-and-junit-2/
+@Fork(value = 1, warmups = 0)
+@Warmup(iterations = 4)
+@Measurement(iterations = 5)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@BenchmarkMode({Mode.AverageTime})
+public class TestFastUtil {
+
+	private static Logger logger = Logger.getLogger(TestFastUtil.class);
+
+	@State(Scope.Benchmark)
+	public static class BenchmarkState {
+		@Param({ "1000", "10000", "100000", "1000000", })
+		public int arraySize;
+	}
+
+	@Benchmark
+	public void memoryUsageDoubleArray(BenchmarkState state) {
+		int size = state.arraySize;
+
+		//long beforeUsedMem=Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory();
+		Random random = new Random();
+		DoubleArrayList numbers = new DoubleArrayList(size);
+		for(int i = 0; i < size; i++) {
+			double number = random.nextDouble();
+			numbers.add(number);
+		}
+
+		//long afterUseMem=Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory();
+		//logger.info("Memory usage [FastUtil] = " + (afterUseMem - beforeUsedMem) / 1000.0 + " [KB]");
+	}
+
+	@Benchmark
+	public void memoryUsageArray(BenchmarkState state) {
+		int size = state.arraySize;
+
+		//long beforeUsedMem=Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory();
+			Random random = new Random();
+			ArrayList<Double> numbers = new ArrayList<>(size);
+			for(int i = 0; i < size; i++) {
+				double number = random.nextDouble();
+				numbers.add(number);
+			}
+
+		//long afterUseMem=Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory();
+		//logger.info("Memory usage [SDK] = " + (afterUseMem - beforeUsedMem) / 1000.0 + " [KB]");
+	}
+}