Tweak best thread selection logic

STC 7 threads:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 26881 W: 4161 L: 3941 D: 18779
http://tests.stockfishchess.org/tests/view/58667a830ebc5903140c632f

LTC 7 threads:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 22988 W: 2767 L: 2583 D: 17638
http://tests.stockfishchess.org/tests/view/586722690ebc5903140c636d

bench: 5468995

diff --git a/src/search.cpp b/src/search.cpp
index 3387091363212dc40b0d88c17e210cdd44d5db8b..a46c44627d4b1677b1f4a0a11f13825d24e0e746 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -312,9 +312,14 @@ void MainThread::search() {
       &&  rootMoves[0].pv[0] != MOVE_NONE)
   {
       for (Thread* th : Threads)
-          if (   th->completedDepth > bestThread->completedDepth
-              && th->rootMoves[0].score > bestThread->rootMoves[0].score)
+      {
+          Depth depthDiff = th->completedDepth - bestThread->completedDepth;
+          Value scoreDiff = th->rootMoves[0].score - bestThread->rootMoves[0].score;
+
+          if (   (depthDiff > 0 && scoreDiff >= 0)
+              || (scoreDiff > 0 && depthDiff >= 0))
               bestThread = th;
+      }
   }
 
   previousScore = bestThread->rootMoves[0].score;