Fix IndexedPointInAreaLocator to reduce calls to synchronized method

modules/core/src/main/java/org/locationtech/jts/algorithm/locate/IndexedPointInAreaLocator.java

@@ -79,7 +79,9 @@ public IndexedPointInAreaLocator(Geometry g)
    */
   public int locate(Coordinate p)
   {
-    createIndex();
+    // avoid calling synchronized method improves performance
+    if (index == null) createIndex();
+
     RayCrossingCounter rcc = new RayCrossingCounter(p);
 
     SegmentVisitor visitor = new SegmentVisitor(rcc);

modules/core/src/test/java/test/jts/perf/algorithm/IndexedPointInAreaPerfTest.java

@@ -0,0 +1,55 @@
+package test.jts.perf.algorithm;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+import org.locationtech.jts.algorithm.locate.IndexedPointInAreaLocator;
+import org.locationtech.jts.geom.Coordinate;
+import org.locationtech.jts.geom.Location;
+import org.locationtech.jts.geom.Polygon;
+import org.locationtech.jts.util.GeometricShapeFactory;
+
+import test.jts.perf.PerformanceTestCase;
+import test.jts.perf.PerformanceTestRunner;
+
+public class IndexedPointInAreaPerfTest extends PerformanceTestCase {
+  public static void main(String args[]) {
+    PerformanceTestRunner.run(IndexedPointInAreaPerfTest.class);
+  }
+
+  public IndexedPointInAreaPerfTest(String name)
+  {
+    super(name);
+    setRunSize(new int[] { 100_000 });
+    setRunIterations(1);
+  }
+
+  List<Coordinate> coords;
+  Polygon polygon;
+
+  public void startRun(int num)
+  {
+    System.out.println("Running with size " + num);
+    GeometricShapeFactory factory = new GeometricShapeFactory();
+    factory.setSize(100);
+    polygon = factory.createCircle();
+
+    coords = new ArrayList<>();
+    Random rand = new Random(1324);
+    for (int i = 0; i < num; i++) {
+      coords.add(new Coordinate(rand.nextDouble()*100, rand.nextDouble()*100));
+    }
+  }
+
+  public void runParallel() {
+    for (int i = 0; i < 1000; i++) {
+      IndexedPointInAreaLocator locator = new IndexedPointInAreaLocator(polygon);
+      coords.parallelStream().forEach(c -> isInside(locator, c));
+    }
+  }
+
+  private boolean isInside(IndexedPointInAreaLocator locator, Coordinate coord) {
+    return locator.locate(coord) == Location.INTERIOR;
+  }
+}