Don't wake up threads at the beginning of the search

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 572a8ac8b2e0b1fda34c6d1867d7069d9653a1ae..5706b959f2d9ffeb1e0a121a001a7a44c31b5c3b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -307,11 +307,7 @@ void Search::think() {
           << endl;
   }
 
-  for (int i = 0; i < Threads.size(); i++)
-  {
-      Threads[i].maxPly = 0;
-      Threads[i].wake_up();
-  }
+  Threads.set_size(Options["Threads"]);
 
   // Set best timer interval to avoid lagging under time pressure. Timer is
   // used to check for remaining available thinking time.
@@ -348,7 +344,7 @@ finalize:
   // but if we are pondering or in infinite search, we shouldn't print the best
   // move before we are told to do so.
   if (!Signals.stop && (Limits.ponder || Limits.infinite))
-      Threads.wait_for_stop_or_ponderhit();
+      Threads[pos.thread()].wait_for_stop_or_ponderhit();
 
   // Best move could be MOVE_NONE when searching on a stalemate position
   cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], Chess960)
@@ -1061,7 +1057,9 @@ split_point_start: // At split points actual search starts from here
               sp->bestValue = value;
               sp->ss->bestMove = move;
               sp->alpha = alpha;
-              sp->is_betaCutoff = (value >= beta);
+
+              if (value >= beta)
+                  sp->cutoff = true;
           }
       }
 
@@ -1864,10 +1862,16 @@ void Thread::idle_loop(SplitPoint* sp_master) {
       {
           assert(!do_sleep && !do_exit);
 
-          // Copy split point position and search stack and call search()
-          Stack ss[MAX_PLY_PLUS_2];
+          lock_grab(Threads.splitLock);
+
+          assert(is_searching);
           SplitPoint* sp = splitPoint;
+
+          lock_release(Threads.splitLock);
+
+          Stack ss[MAX_PLY_PLUS_2];
           Position pos(*sp->pos, threadID);
+          int master = sp->master;
 
           memcpy(ss, sp->ss - 1, 4 * sizeof(Stack));
           (ss+1)->sp = sp;
@@ -1885,21 +1889,26 @@ void Thread::idle_loop(SplitPoint* sp_master) {
 
           assert(is_searching);
 
-          // We return from search with lock held
+          is_searching = false;
           sp->slavesMask &= ~(1ULL << threadID);
           sp->nodes += pos.nodes_searched();
-          lock_release(sp->lock);
 
-          is_searching = false;
+          // After releasing the lock we cannot access anymore any SplitPoint
+          // related data in a reliably way becuase it could have been released
+          // under our feet by the sp master.
+          lock_release(sp->lock);
 
           // Wake up master thread so to allow it to return from the idle loop in
           // case we are the last slave of the split point.
           if (   Threads.use_sleeping_threads()
-              && threadID != sp->master
-              && !Threads[sp->master].is_searching)
-              Threads[sp->master].wake_up();
+              && threadID != master
+              && !Threads[master].is_searching)
+              Threads[master].wake_up();
       }
   }
+  // In helpful master concept a master can help only a sub-tree of its split
+  // point, and because here is all finished is not possible master is booked.
+  assert(!is_searching);
 }