Thanks. This was fixed in https://sourceforge.net/p/jts-topo-suite/code/725/ . It will be in the 1.14 release (real soon now hopefully...)
On Thu, Aug 27, 2015 at 7:34 AM, Christoph Pirkl <[email protected]> wrote: > Class com.vividsolutions.jts.algorithm.distance.PointPairDistance is > not thread safe as it uses tempSegment as a single temporary variable > for all threads. > > In my case computeDistance() was called concurrently and in some rare > cases the PointPairDistance passed as a parameter had invalid > coordinates (ppd.getCoordinate(0) was (NaN, NaN, NaN)). > > My suggestion is to make the field non-static and create a new > instance of the class for each call, e.g.: > > -------------- > public class DistanceToPointThreadSafe > { > // used for point-line distance calculation > private final LineSegment tempSegment = new LineSegment(); > > private DistanceToPointThreadSafe() > { > } > > public static PointPairDistance computeDistance(Geometry geom, > Coordinate pt) > { > final PointPairDistance pointPairDistance = new > PointPairDistance(); > new DistanceToPointThreadSafe().computeDistance(geom, pt, > pointPairDistance); > return pointPairDistance; > } > > private void computeDistance(Geometry geom, Coordinate pt, > PointPairDistance ptDist) > { > if (geom instanceof LineString) > { > computeDistance((LineString)geom, pt, ptDist); > } > else if (geom instanceof Polygon) > { > computeDistance((Polygon)geom, pt, ptDist); > } > else if (geom instanceof GeometryCollection) > { > final GeometryCollection gc = (GeometryCollection)geom; > for (int i = 0; i < gc.getNumGeometries(); i++) > { > final Geometry g = gc.getGeometryN(i); > computeDistance(g, pt, ptDist); > } > } > else > { // assume geom is Point > ptDist.setMinimum(geom.getCoordinate(), pt); > } > } > > private void computeDistance(LineString line, Coordinate pt, > PointPairDistance ptDist) > { > final Coordinate[] coords = line.getCoordinates(); > for (int i = 0; i < coords.length - 1; i++) > { > tempSegment.setCoordinates(coords[i], coords[i + 1]); > // this is somewhat inefficient - could do better > final Coordinate closestPt = tempSegment.closestPoint(pt); > ptDist.setMinimum(closestPt, pt); > } > } > > private void computeDistance(Polygon poly, Coordinate pt, > PointPairDistance ptDist) > { > computeDistance(poly.getExteriorRing(), pt, ptDist); > for (int i = 0; i < poly.getNumInteriorRing(); i++) > { > computeDistance(poly.getInteriorRingN(i), pt, ptDist); > } > } > } > ------------- > > Kind regards, > Christoph. > > > ------------------------------------------------------------------------------ > _______________________________________________ > Jts-topo-suite-user mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/jts-topo-suite-user >
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