Don't wake up /sleep threads in think() anymore

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 46dd53ebd1e7919bb937699d649f1996b7553939..29d022added67563087a207714086d02c45b50fe 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -83,7 +83,6 @@ namespace {
     bool thread_is_available(int slave, int master) const;
     bool thread_should_stop(int threadID) const;
     void wake_sleeping_thread(int threadID);
-    void put_threads_to_sleep();
     void idle_loop(int threadID, SplitPoint* sp);
 
     template <bool Fake>
@@ -96,7 +95,7 @@ namespace {
     int ActiveThreads;
     volatile bool AllThreadsShouldExit;
     Thread threads[MAX_THREADS];
-    Lock MPLock, WaitLock;
+    Lock MPLock;
     WaitCondition WaitCond[MAX_THREADS];
   };
 
@@ -465,10 +464,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int time[], int incr
       init_eval(ThreadsMgr.active_threads());
   }
 
-  // Wake up needed threads
-  for (int i = 1; i < newActiveThreads; i++)
-      ThreadsMgr.wake_sleeping_thread(i);
-
   // Set thinking time
   int myTime = time[pos.side_to_move()];
   int myIncrement = increment[pos.side_to_move()];
@@ -501,8 +496,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int time[], int incr
   if (UseLogFile)
       LogFile.close();
 
-  ThreadsMgr.put_threads_to_sleep();
-
   return !Quit;
 }
 
@@ -2225,7 +2218,8 @@ split_point_start: // At split points actual search starts from here
         // If we are not thinking, wait for a condition to be signaled
         // instead of wasting CPU time polling for work.
         while (   threadID >= ActiveThreads
-               || threads[threadID].state == THREAD_INITIALIZING)
+               || threads[threadID].state == THREAD_INITIALIZING
+               || (!sp && threads[threadID].state == THREAD_AVAILABLE))
         {
             assert(!sp);
             assert(threadID != 0);
@@ -2233,16 +2227,21 @@ split_point_start: // At split points actual search starts from here
             if (AllThreadsShouldExit)
                 break;
 
-            threads[threadID].state = THREAD_AVAILABLE;
+            lock_grab(&MPLock);
 
-#if !defined(_MSC_VER)
-            lock_grab(&WaitLock);
-            if (threadID >= ActiveThreads)
-                pthread_cond_wait(&WaitCond[threadID], &WaitLock);
-            lock_release(&WaitLock);
-#else
-            WaitForSingleObject(WaitCond[threadID], INFINITE);
-#endif
+            // Retest condition under lock protection
+            if (!(   threadID >= ActiveThreads
+                  || threads[threadID].state == THREAD_INITIALIZING
+                  || (!sp && threads[threadID].state == THREAD_AVAILABLE)))
+            {
+                lock_release(&MPLock);
+                continue;
+            }
+
+            // Put thread to sleep
+            threads[threadID].state = THREAD_AVAILABLE;
+            cond_wait(&WaitCond[threadID], &MPLock);
+            lock_release(&MPLock);
         }
 
         // If this thread has been assigned work, launch a search
@@ -2302,14 +2301,9 @@ split_point_start: // At split points actual search starts from here
 
     // Initialize global locks
     lock_init(&MPLock);
-    lock_init(&WaitLock);
 
     for (i = 0; i < MAX_THREADS; i++)
-#if !defined(_MSC_VER)
-        pthread_cond_init(&WaitCond[i], NULL);
-#else
-        WaitCond[i] = CreateEvent(0, FALSE, FALSE, 0);
-#endif
+        cond_init(&WaitCond[i]);
 
     // Initialize splitPoints[] locks
     for (i = 0; i < MAX_THREADS; i++)
@@ -2369,7 +2363,6 @@ split_point_start: // At split points actual search starts from here
         for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
             lock_destroy(&(threads[i].splitPoints[j].lock));
 
-    lock_destroy(&WaitLock);
     lock_destroy(&MPLock);
 
     // Now we can safely destroy the wait conditions
@@ -2535,6 +2528,8 @@ split_point_start: // At split points actual search starts from here
             assert(i == master || threads[i].state == THREAD_BOOKED);
 
             threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop()
+            if (i != master)
+                wake_sleeping_thread(i);
         }
 
     // Everything is set up. The master thread enters the idle loop, from
@@ -2562,29 +2557,12 @@ split_point_start: // At split points actual search starts from here
 
   void ThreadsManager::wake_sleeping_thread(int threadID) {
 
-    assert(threadID > 0);
-    assert(threads[threadID].state == THREAD_AVAILABLE);
-
-#if !defined(_MSC_VER)
-        pthread_mutex_lock(&WaitLock);
-        pthread_cond_signal(&WaitCond[threadID]);
-        pthread_mutex_unlock(&WaitLock);
-#else
-        SetEvent(WaitCond[threadID]);
-#endif
+     lock_grab(&MPLock);
+     cond_signal(&WaitCond[threadID]);
+     lock_release(&MPLock);
   }
 
 
-  // put_threads_to_sleep() makes all the threads go to sleep just before
-  // to leave think(), at the end of the search. Threads should have already
-  // finished the job and should be idle.
-
-  void ThreadsManager::put_threads_to_sleep() {
-
-    // This makes the threads to go to sleep
-    ActiveThreads = 1;
-  }
-
   /// The RootMoveList class
 
   // RootMoveList c'tor