Changeset 13233

Timestamp:

11/17/15 19:03:18 (9 years ago)

Author:

gkronber

Message:

#2512: synchronized access to PRNG in GEArtificialAntProblem

File:

• trunk/sources/HeuristicLab.Problems.GrammaticalEvolution/3.4/ArtificialAnt/GEArtificialAntProblem.cs (modified) (2 diffs)

trunk/sources/HeuristicLab.Problems.GrammaticalEvolution/3.4/ArtificialAnt/GEArtificialAntProblem.cs

@@ -33 +33 @@
 using HeuristicLab.Problems.GeneticProgramming.ArtificialAnt;
 using HeuristicLab.Problems.GrammaticalEvolution.Mappers;
+using HeuristicLab.Random;
 
 namespace HeuristicLab.Problems.GrammaticalEvolution {
@@ -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 (random) {
+        fastRand = new FastRandom(random.Next());
+      }
+      var tree = mapper.Map(fastRand, bounds, len, grammar, vector);
 
       Interpreter interpreter = new Interpreter(tree, World, MaxTimeSteps);