X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=d845fdf2e4183f2fdaa10bb656b66d1ab6439749;hp=6044d0aa0df5777bdc0f89d72ccc6999d5caf662;hb=83d8fe2d59bad718de70b00ac2c8fddfadda76b5;hpb=7d5b8fcf7724a66f191cae45d858a1b3d63c2bce

diff --git a/src/thread.cpp b/src/thread.cpp
index 6044d0aa..d845fdf2 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -27,7 +27,7 @@ ThreadsManager Threads; // Global object definition
 namespace { extern "C" {
 
  // start_routine() is the C function which is called when a new thread
- // is launched. It simply calls idle_loop() of the supplied threadID.
+ // is launched. It simply calls idle_loop() of the supplied thread.
  // There are two versions of this function; one for POSIX threads and
  // one for Windows threads.
 
@@ -63,9 +63,8 @@ void Thread::wake_up() {
 }
 
 
-// cutoff_occurred() checks whether a beta cutoff has occurred in
-// the thread's currently active split point, or in some ancestor of
-// the current split point.
+// cutoff_occurred() checks whether a beta cutoff has occurred in the current
+// active split point, or in some ancestor of the split point.
 
 bool Thread::cutoff_occurred() const {
 
@@ -85,7 +84,7 @@ bool Thread::cutoff_occurred() const {
 
 bool Thread::is_available_to(int master) const {
 
-  if (state != AVAILABLE)
+  if (is_searching)
       return false;
 
   // Make a local copy to be sure doesn't become zero under our feet while
@@ -148,11 +147,6 @@ void ThreadsManager::set_size(int cnt) {
 
 void ThreadsManager::init() {
 
-  // Threads will go to sleep as soon as created, only main thread is kept alive
-  set_size(1);
-  threads[0].state = Thread::SEARCHING;
-  threads[0].threadID = 0;
-
   // Initialize threads lock, used when allocating slaves during splitting
   lock_init(&threadsLock);
 
@@ -166,10 +160,16 @@ void ThreadsManager::init() {
           lock_init(&(threads[i].splitPoints[j].lock));
   }
 
-  // Create and startup all the threads but the main that is already running
+  // Initialize main thread's associated data
+  threads[0].is_searching = true;
+  threads[0].threadID = 0;
+  set_size(1); // This makes all the threads but the main to go to sleep
+
+  // Create and launch all the threads but the main that is already running,
+  // threads will go immediately to sleep.
   for (int i = 1; i < MAX_THREADS; i++)
   {
-      threads[i].state = Thread::AVAILABLE;
+      threads[i].is_searching = false;
       threads[i].threadID = i;
 
 #if defined(_MSC_VER)
@@ -192,20 +192,24 @@ void ThreadsManager::init() {
 
 void ThreadsManager::exit() {
 
+  // Wake up all the slave threads at once. This is faster than "wake and wait"
+  // for each thread and avoids a rare crash once every 10K games under Linux.
+  for (int i = 1; i < MAX_THREADS; i++)
+  {
+      threads[i].do_terminate = true;
+      threads[i].wake_up();
+  }
+
   for (int i = 0; i < MAX_THREADS; i++)
   {
-      // Wake up all the slave threads and wait for termination
       if (i != 0)
       {
-          threads[i].do_terminate = true;
-          threads[i].wake_up();
-
+          // Wait for slave termination
 #if defined(_MSC_VER)
           WaitForSingleObject(threads[i].handle, 0);
           CloseHandle(threads[i].handle);
 #else
           pthread_join(threads[i].handle, NULL);
-          pthread_detach(threads[i].handle);
 #endif
       }
 
@@ -287,7 +291,7 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
       sp->is_slave[i] = false;
 
   // If we are here it means we are not available
-  assert(masterThread.state == Thread::SEARCHING);
+  assert(masterThread.is_searching);
 
   int workersCnt = 1; // At least the master is included
 
@@ -304,7 +308,7 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
           threads[i].splitPoint = sp;
 
           // This makes the slave to exit from idle_loop()
-          threads[i].state = Thread::WORKISWAITING;
+          threads[i].is_searching = true;
 
           if (useSleepingThreads)
               threads[i].wake_up();
@@ -318,25 +322,24 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
 
   masterThread.splitPoint = sp;
   masterThread.activeSplitPoints++;
-  masterThread.state = Thread::WORKISWAITING;
 
-  // Everything is set up. The master thread enters the idle loop, from
-  // which it will instantly launch a search, because its state is
-  // Thread::WORKISWAITING. We send the split point as a second parameter to
-  // the idle loop, which means that the main thread will return from the idle
-  // loop when all threads have finished their work at this split point.
+  // Everything is set up. The master thread enters the idle loop, from which
+  // it will instantly launch a search, because its is_searching flag is set.
+  // We pass the split point as a parameter to the idle loop, which means that
+  // the thread will return from the idle loop when all slaves have finished
+  // their work at this split point.
   masterThread.idle_loop(sp);
 
   // In helpful master concept a master can help only a sub-tree, and
   // because here is all finished is not possible master is booked.
-  assert(masterThread.state == Thread::AVAILABLE);
+  assert(!masterThread.is_searching);
 
   // We have returned from the idle loop, which means that all threads are
   // finished. Note that changing state and decreasing activeSplitPoints is done
   // under lock protection to avoid a race with Thread::is_available_to().
   lock_grab(&threadsLock);
 
-  masterThread.state = Thread::SEARCHING;
+  masterThread.is_searching = true;
   masterThread.activeSplitPoints--;
 
   lock_release(&threadsLock);