Changeset 13281

Timestamp:

11/19/15 11:43:07 (3 years ago)

Author:

gkronber

Message:

#2512: merged r13233, r13243 from trunk to stable

Location:

stable

Files:

• . (modified) (1 prop)
• HeuristicLab.Problems.GrammaticalEvolution (modified) (1 prop)
• HeuristicLab.Problems.GrammaticalEvolution/3.4/ArtificialAnt/GEArtificialAntProblem.cs (modified) (4 diffs)

stable/HeuristicLab.Problems.GrammaticalEvolution/3.4/ArtificialAnt/GEArtificialAntProblem.cs

@@ -22 +22 @@
 #endregion
 
-using System.Diagnostics.Contracts;
 using System.Linq;
 using HeuristicLab.Common;
@@ -33 +32 @@
 using HeuristicLab.Problems.GeneticProgramming.ArtificialAnt;
 using HeuristicLab.Problems.GrammaticalEvolution.Mappers;
+using HeuristicLab.Random;
 
 namespace HeuristicLab.Problems.GrammaticalEvolution {
@@ -98 +98 @@
     }
 
+    private readonly object syncRoot = new object();
     public override double Evaluate(Individual individual, IRandom random) {
       var vector = individual.IntegerVector();
@@ -106 +107 @@
       var mapper = GenotypeToPhenotypeMapperParameter.Value;
 
-      var tree = mapper.Map(random, bounds, len, grammar, vector);
+      // Evaluate might be called concurrently therefore access to random has to be synchronized.
+      // However, results depend on the order of execution. Therefore, results might be different for the same seed when using the parallel engine.
+      IRandom fastRand;
+      lock (syncRoot) {
+        fastRand = new FastRandom(random.Next());
+      }
+      var tree = mapper.Map(fastRand, bounds, len, grammar, vector);
 
       Interpreter interpreter = new Interpreter(tree, World, MaxTimeSteps);