X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=d845fdf2e4183f2fdaa10bb656b66d1ab6439749;hp=c7cabeb7e131afcdc75d4a036666c8c6407449a7;hb=83d8fe2d59bad718de70b00ac2c8fddfadda76b5;hpb=92d70fb6677f4ed0568aa50f239ceea2d8a1cd97 diff --git a/src/thread.cpp b/src/thread.cpp index c7cabeb7..d845fdf2 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -27,23 +27,23 @@ 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() 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; } @@ -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 @@ -111,30 +110,47 @@ void ThreadsManager::read_uci_options() { maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value(); minimumSplitDepth = Options["Minimum Split Depth"].value() * ONE_PLY; useSleepingThreads = Options["Use Sleeping Threads"].value(); - activeThreads = Options["Threads"].value(); + + set_size(Options["Threads"].value()); } -// 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) { + + assert(cnt > 0 && cnt <= MAX_THREADS); - int threadID[MAX_THREADS]; + activeThreads = cnt; - // This flag is needed to properly end the threads when program exits - allThreadsShouldExit = false; + 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; +} - // Threads will sent to sleep as soon as created, only main thread is kept alive - activeThreads = 1; - threads[0].state = Thread::SEARCHING; - // 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. - lock_init(&mpLock); +void ThreadsManager::init() { - // Initialize thread and split point locks + // Initialize threads lock, used when allocating slaves during splitting + lock_init(&threadsLock); + + // Initialize sleep and split point locks for (int i = 0; i < MAX_THREADS; i++) { lock_init(&threads[i].sleepLock); @@ -144,48 +160,60 @@ 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::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) {} } } -// exit() is called to cleanly exit the threads when the program finishes +// exit() is called to cleanly terminate the threads when the program finishes 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 waits 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 the locks and wait conditions + // Now we can safely destroy locks and wait conditions lock_destroy(&threads[i].sleepLock); cond_destroy(&threads[i].sleepCond); @@ -193,23 +221,7 @@ void ThreadsManager::exit() { lock_destroy(&(threads[i].splitPoints[j].lock)); } - lock_destroy(&mpLock); -} - - -// 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(); - } + lock_destroy(&threadsLock); } @@ -238,13 +250,13 @@ bool ThreadsManager::available_slave_exists(int master) const { // call search().When all threads have returned from search() then split() returns. template -void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta, - Value* bestValue, Depth depth, Move threatMove, - int moveCount, MovePicker* mp, bool pvNode) { +Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value beta, + Value bestValue, Depth depth, Move threatMove, + int moveCount, MovePicker* mp, int nodeType) { assert(pos.is_ok()); - assert(*bestValue >= -VALUE_INFINITE); - assert(*bestValue <= *alpha); - assert(*alpha < beta); + assert(bestValue >= -VALUE_INFINITE); + assert(bestValue <= alpha); + assert(alpha < beta); assert(beta <= VALUE_INFINITE); assert(depth > DEPTH_ZERO); assert(pos.thread() >= 0 && pos.thread() < activeThreads); @@ -253,93 +265,91 @@ void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const V int i, master = pos.thread(); Thread& masterThread = threads[master]; - lock_grab(&mpLock); - - // If no other thread is available to help us, or if we have too many - // active split points, don't split. - if ( !available_slave_exists(master) - || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) - { - lock_release(&mpLock); - return; - } + // If we already have too many active split points, don't split + if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) + return bestValue; // Pick the next available split point object from the split point stack - SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++]; + SplitPoint* sp = masterThread.splitPoints + masterThread.activeSplitPoints; // Initialize the split point object - splitPoint.parent = masterThread.splitPoint; - splitPoint.master = master; - splitPoint.is_betaCutoff = false; - splitPoint.depth = depth; - splitPoint.threatMove = threatMove; - splitPoint.alpha = *alpha; - splitPoint.beta = beta; - splitPoint.pvNode = pvNode; - splitPoint.bestValue = *bestValue; - splitPoint.mp = mp; - splitPoint.moveCount = moveCount; - splitPoint.pos = &pos; - splitPoint.nodes = 0; - splitPoint.ss = ss; + sp->parent = masterThread.splitPoint; + sp->master = master; + sp->is_betaCutoff = false; + sp->depth = depth; + sp->threatMove = threatMove; + sp->alpha = alpha; + sp->beta = beta; + sp->nodeType = nodeType; + sp->bestValue = bestValue; + sp->mp = mp; + sp->moveCount = moveCount; + sp->pos = &pos; + sp->nodes = 0; + sp->ss = ss; for (i = 0; i < activeThreads; i++) - splitPoint.is_slave[i] = false; - - masterThread.splitPoint = &splitPoint; + sp->is_slave[i] = false; // If we are here it means we are not available - assert(masterThread.state != Thread::AVAILABLE); + assert(masterThread.is_searching); int workersCnt = 1; // At least the master is included - // Allocate available threads setting state to THREAD_BOOKED + // Try to allocate available threads and ask them to start searching setting + // the state to Thread::WORKISWAITING, this must be done under lock protection + // to avoid concurrent allocation of the same slave by another master. + lock_grab(&threadsLock); + for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++) if (i != master && threads[i].is_available_to(master)) { - threads[i].state = Thread::BOOKED; - threads[i].splitPoint = &splitPoint; - splitPoint.is_slave[i] = true; workersCnt++; - } + sp->is_slave[i] = true; + threads[i].splitPoint = sp; - assert(Fake || workersCnt > 1); + // This makes the slave to exit from idle_loop() + threads[i].is_searching = true; - // We can release the lock because slave threads are already booked and master is not available - lock_release(&mpLock); + if (useSleepingThreads) + threads[i].wake_up(); + } - // Tell the threads that they have work to do. This will make them leave - // their idle loop. - for (i = 0; i < activeThreads; i++) - if (i == master || splitPoint.is_slave[i]) - { - assert(i == master || threads[i].state == Thread::BOOKED); + lock_release(&threadsLock); - threads[i].state = Thread::WORKISWAITING; // This makes the slave to exit from idle_loop() + // We failed to allocate even one slave, return + if (!Fake && workersCnt == 1) + return bestValue; - if (useSleepingThreads && i != master) - threads[i].wake_up(); - } + masterThread.splitPoint = sp; + masterThread.activeSplitPoints++; + + // 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); - // 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, &splitPoint); + // 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.is_searching); // We have returned from the idle loop, which means that all threads are - // finished. Update alpha and bestValue, and return. - lock_grab(&mpLock); + // 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); - *alpha = splitPoint.alpha; - *bestValue = splitPoint.bestValue; + masterThread.is_searching = true; masterThread.activeSplitPoints--; - masterThread.splitPoint = splitPoint.parent; - pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes); - lock_release(&mpLock); + lock_release(&threadsLock); + + masterThread.splitPoint = sp->parent; + pos.set_nodes_searched(pos.nodes_searched() + sp->nodes); + + return sp->bestValue; } // Explicit template instantiations -template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool); -template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool); +template Value ThreadsManager::split(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int); +template Value ThreadsManager::split(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);