namespace { extern "C" {
// start_routine() is the C function which is called when a new thread
- // is launched. It simply calls idle_loop() with 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.
#if defined(_MSC_VER)
- DWORD WINAPI start_routine(LPVOID threadID) {
+ DWORD WINAPI start_routine(LPVOID thread) {
- Threads.idle_loop(*(int*)threadID, NULL);
+ ((Thread*)thread)->idle_loop(NULL);
return 0;
}
#else
- void* start_routine(void* threadID) {
+ void* start_routine(void* thread) {
- Threads.idle_loop(*(int*)threadID, NULL);
+ ((Thread*)thread)->idle_loop(NULL);
return NULL;
}
}
-// 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 {
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
maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value<int>();
minimumSplitDepth = Options["Minimum Split Depth"].value<int>() * ONE_PLY;
useSleepingThreads = Options["Use Sleeping Threads"].value<bool>();
- activeThreads = Options["Threads"].value<int>();
+
+ set_size(Options["Threads"].value<int>());
}
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
+// set_size() changes the number of active threads and raises do_sleep flag for
+// all the unused threads that will go immediately to sleep.
-void ThreadsManager::init() {
+void ThreadsManager::set_size(int cnt) {
- int threadID[MAX_THREADS];
+ assert(cnt > 0 && cnt <= MAX_THREADS);
- // This flag is needed to properly end the threads when program exits
- allThreadsShouldExit = false;
+ activeThreads = cnt;
- // Threads will sent to sleep as soon as created, only main thread is kept alive
- activeThreads = 1;
- threads[0].state = Thread::SEARCHING;
+ for (int i = 0; i < MAX_THREADS; i++)
+ if (i < activeThreads)
+ {
+ // Dynamically allocate pawn and material hash tables according to the
+ // number of active threads. This avoids preallocating memory for all
+ // possible threads if only few are used as, for instance, on mobile
+ // devices where memory is scarce and allocating for MAX_THREADS could
+ // even result in a crash.
+ threads[i].pawnTable.init();
+ threads[i].materialTable.init();
+
+ threads[i].do_sleep = false;
+ }
+ else
+ threads[i].do_sleep = true;
+}
- // Allocate pawn and material hash tables for main thread
- init_hash_tables();
+
+// init() is called during startup. Initializes locks and condition variables
+// and launches all threads sending them immediately to sleep.
+
+void ThreadsManager::init() {
// Initialize threads lock, used when allocating slaves during splitting
lock_init(&threadsLock);
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::INITIALIZING;
- threadID[i] = i;
+ threads[i].is_searching = false;
+ threads[i].threadID = i;
#if defined(_MSC_VER)
- bool ok = (CreateThread(NULL, 0, start_routine, (LPVOID)&threadID[i], 0, NULL) != NULL);
+ threads[i].handle = CreateThread(NULL, 0, start_routine, (LPVOID)&threads[i], 0, NULL);
+ bool ok = (threads[i].handle != NULL);
#else
- pthread_t pthreadID;
- bool ok = (pthread_create(&pthreadID, NULL, start_routine, (void*)&threadID[i]) == 0);
- pthread_detach(pthreadID);
+ bool ok = (pthread_create(&threads[i].handle, NULL, start_routine, (void*)&threads[i]) == 0);
#endif
+
if (!ok)
{
- std::cout << "Failed to create thread number " << i << std::endl;
+ std::cerr << "Failed to create thread number " << i << std::endl;
::exit(EXIT_FAILURE);
}
-
- // Wait until the thread has finished launching and is gone to sleep
- while (threads[i].state == Thread::INITIALIZING) {}
}
}
void ThreadsManager::exit() {
- // Force the woken up threads to exit idle_loop() and hence terminate
- allThreadsShouldExit = true;
+ // 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 threads and wait for termination
if (i != 0)
{
- threads[i].wake_up();
- while (threads[i].state != Thread::TERMINATED) {}
+ // Wait for slave termination
+#if defined(_MSC_VER)
+ WaitForSingleObject(threads[i].handle, 0);
+ CloseHandle(threads[i].handle);
+#else
+ pthread_join(threads[i].handle, NULL);
+#endif
}
// Now we can safely destroy locks and wait conditions
}
-// init_hash_tables() dynamically allocates pawn and material hash tables
-// according to the number of active threads. This avoids preallocating
-// memory for all possible threads if only few are used as, for instance,
-// on mobile devices where memory is scarce and allocating for MAX_THREADS
-// threads could even result in a crash.
-
-void ThreadsManager::init_hash_tables() {
-
- for (int i = 0; i < activeThreads; i++)
- {
- threads[i].pawnTable.init();
- threads[i].materialTable.init();
- }
-}
-
-
// available_slave_exists() tries to find an idle thread which is available as
// a slave for the thread with threadID "master".
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
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();
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.
- idle_loop(master, sp);
+ // 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);
projects / stockfish / blobdiff