Replacing the termination logic to reduce run-times with marginal effect on quality.

jsprit-core/src/main/java/com/graphhopper/jsprit/core/algorithm/SearchStrategy.java

@@ -164,7 +164,5 @@ public class SearchStrategy {
         for (SearchStrategyModule module : searchStrategyModules) {
             module.addModuleListener(moduleListener);
         }
-
     }
-
 }

jsprit-core/src/main/java/com/graphhopper/jsprit/core/algorithm/termination/IterationWithoutImprovementTermination.java

@@ -18,9 +18,13 @@
 package com.graphhopper.jsprit.core.algorithm.termination;
 
 import com.graphhopper.jsprit.core.algorithm.SearchStrategy;
+import com.graphhopper.jsprit.core.problem.solution.VehicleRoutingProblemSolution;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.ArrayList;
+import java.util.List;
+
 
 /**
  * Terminates algorithm prematurely based on iterations without any improvement (i.e. new solution acceptance).
@@ -39,6 +43,11 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
 
     private int iterationsWithoutImprovement = 0;
 
+    private List<Double> costs;
+
+    private List<Integer> unassignedCount;
+
+    private int bestCost = Integer.MAX_VALUE;
     /**
      * Constructs termination.
      *
@@ -46,6 +55,8 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
      */
     public IterationWithoutImprovementTermination(int noIterationsWithoutImprovement) {
         this.noIterationWithoutImprovement = noIterationsWithoutImprovement;
+        costs = new ArrayList<>();
+        unassignedCount = new ArrayList<>();
         log.debug("initialise " + this);
     }
 
@@ -56,10 +67,21 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
 
     @Override
     public boolean isPrematureBreak(SearchStrategy.DiscoveredSolution discoveredSolution) {
-        if (discoveredSolution.isAccepted()) iterationsWithoutImprovement = 0;
+        VehicleRoutingProblemSolution sol = discoveredSolution.getSolution();
-        else iterationsWithoutImprovement++;
+        double currentCost = sol.getCost();
-        return (iterationsWithoutImprovement > noIterationWithoutImprovement);
+        costs.add(Math.min(currentCost, bestCost));
+        int currentUnassigned = sol.getUnassignedJobs().size();
+        unassignedCount.add(currentUnassigned);
+
+        int i = costs.size() - 1;
+        if (i < noIterationWithoutImprovement)
+            return false;
+
+        int progressPercentTerminationCondition = 1; // TODO: Move to configuration
+        boolean unassignedEqual = (currentUnassigned == unassignedCount.get(i-noIterationWithoutImprovement));
+        boolean progressTooSlow = (100 * Math.abs(currentCost - costs.get(i - noIterationWithoutImprovement))) / currentCost < progressPercentTerminationCondition;
+
+        return (unassignedEqual && progressTooSlow);
     }
 
-
 }

jsprit-core/src/main/java/com/graphhopper/jsprit/core/reporting/SolutionPrinter.java

@@ -131,7 +131,7 @@ public class SolutionPrinter {
         out.format("+---------------+------------------------------------------+%n");
         out.printf("| indicator     | value                                    |%n");
         out.format("+---------------+------------------------------------------+%n");
-        out.format(leftAlignSolution, "costs", solution.getCost());
+        out.format(leftAlignSolution, "costs", Math.round(solution.getCost()));
         out.format(leftAlignSolution, "noVehicles", solution.getRoutes().size());
         out.format(leftAlignSolution, "unassgndJobs", solution.getUnassignedJobs().size());
         out.format("+----------------------------------------------------------+%n");