X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=d9fa9c512c53cc1a5919ebdf2926035876b793a3;hp=2c40ef6f8c14ecc7ccc218a01d06dada354d8874;hb=831f91b859c43a5fa895ef0c955516ec8b7a8212;hpb=3d937e1e901c59c04cd5d602c05f72892222ded8 diff --git a/src/thread.cpp b/src/thread.cpp index 2c40ef6f..d9fa9c51 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -27,216 +27,249 @@ using namespace Search; -ThreadsManager Threads; // Global object +ThreadPool Threads; // Global object 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 thread. The first - // and last thread are special. First one is the main search thread while the - // last one mimics a timer, they run in main_loop() and timer_loop(). + // is launched. It is a wrapper to member function pointed by start_fn. -#if defined(_MSC_VER) - DWORD WINAPI start_routine(LPVOID thread) { -#else - void* start_routine(void* thread) { -#endif + long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; } - Thread* th = (Thread*)thread; +} } + + +// Thread c'tor starts a newly-created thread of execution that will call +// the idle loop function pointed by start_fn going immediately to sleep. - if (th->threadID == 0) - th->main_loop(); +Thread::Thread(Fn fn) { - else if (th->threadID == MAX_THREADS) - th->timer_loop(); + is_searching = do_exit = false; + maxPly = splitPointsCnt = 0; + curSplitPoint = NULL; + start_fn = fn; + idx = Threads.size(); - else - th->idle_loop(NULL); + do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching() - return 0; + if (!thread_create(handle, start_routine, this)) + { + std::cerr << "Failed to create thread number " << idx << std::endl; + ::exit(EXIT_FAILURE); } +} -} } + +// Thread d'tor waits for thread termination before to return. + +Thread::~Thread() { + + assert(do_sleep); + + do_exit = true; // Search must be already finished + wake_up(); + thread_join(handle); // Wait for thread termination +} + + +// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and +// then calls check_time(). If maxPly is 0 thread sleeps until is woken up. +extern void check_time(); + +void Thread::timer_loop() { + + while (!do_exit) + { + mutex.lock(); + sleepCondition.wait_for(mutex, maxPly ? maxPly : INT_MAX); + mutex.unlock(); + check_time(); + } +} + + +// Thread::main_loop() is where the main thread is parked waiting to be started +// when there is a new search. Main thread will launch all the slave threads. + +void Thread::main_loop() { + + while (true) + { + mutex.lock(); + + do_sleep = true; // Always return to sleep after a search + is_searching = false; + + while (do_sleep && !do_exit) + { + Threads.sleepCondition.notify_one(); // Wake up UI thread if needed + sleepCondition.wait(mutex); + } + + mutex.unlock(); + + if (do_exit) + return; + + is_searching = true; + + Search::think(); + + assert(is_searching); + } +} -// wake_up() wakes up the thread, normally at the beginning of the search or, -// if "sleeping threads" is used, when there is some work to do. +// Thread::wake_up() wakes up the thread, normally at the beginning of the search +// or, if "sleeping threads" is used at split time. void Thread::wake_up() { - lock_grab(sleepLock); - cond_signal(sleepCond); - lock_release(sleepLock); + mutex.lock(); + sleepCondition.notify_one(); + mutex.unlock(); +} + + +// Thread::wait_for_stop_or_ponderhit() is called when the maximum depth is +// reached while the program is pondering. The point is to work around a wrinkle +// in the UCI protocol: When pondering, the engine is not allowed to give a +// "bestmove" before the GUI sends it a "stop" or "ponderhit" command. We simply +// wait here until one of these commands (that raise StopRequest) is sent and +// then return, after which the bestmove and pondermove will be printed. + +void Thread::wait_for_stop_or_ponderhit() { + + Signals.stopOnPonderhit = true; + + mutex.lock(); + while (!Signals.stop) sleepCondition.wait(mutex);; + mutex.unlock(); } -// cutoff_occurred() checks whether a beta cutoff has occurred in the current -// active split point, or in some ancestor of the split point. +// Thread::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 { - for (SplitPoint* sp = splitPoint; sp; sp = sp->parent) - if (sp->is_betaCutoff) + for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent) + if (sp->cutoff) return true; return false; } -// is_available_to() checks whether the thread is available to help the thread with -// threadID "master" at a split point. An obvious requirement is that thread must be -// idle. With more than two threads, this is not by itself sufficient: If the thread -// is the master of some active split point, it is only available as a slave to the -// threads which are busy searching the split point at the top of "slave"'s split +// Thread::is_available_to() checks whether the thread is available to help the +// thread 'master' at a split point. An obvious requirement is that thread must +// be idle. With more than two threads, this is not sufficient: If the thread is +// the master of some active split point, it is only available as a slave to the +// slaves which are busy searching the split point at the top of slaves split // point stack (the "helpful master concept" in YBWC terminology). -bool Thread::is_available_to(int master) const { +bool Thread::is_available_to(Thread* master) const { if (is_searching) return false; // Make a local copy to be sure doesn't become zero under our feet while // testing next condition and so leading to an out of bound access. - int localActiveSplitPoints = activeSplitPoints; + int spCnt = splitPointsCnt; // No active split points means that the thread is available as a slave for any // other thread otherwise apply the "helpful master" concept if possible. - if ( !localActiveSplitPoints - || splitPoints[localActiveSplitPoints - 1].is_slave[master]) - return true; - - return false; + return !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx)); } -// read_uci_options() updates number of active threads and other parameters -// according to the UCI options values. It is called before to start a new search. +// init() is called at startup. Initializes lock and condition variable and +// launches requested threads sending them immediately to sleep. We cannot use +// a c'tor becuase Threads is a static object and we need a fully initialized +// engine at this point due to allocation of endgames in Thread c'tor. -void ThreadsManager::read_uci_options() { +void ThreadPool::init() { - maxThreadsPerSplitPoint = Options["Max Threads per Split Point"]; - minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; - useSleepingThreads = Options["Use Sleeping Threads"]; - - set_size(Options["Threads"]); + timer = new Thread(&Thread::timer_loop); + threads.push_back(new Thread(&Thread::main_loop)); + read_uci_options(); } -// 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::set_size(int cnt) { +// exit() cleanly terminates the threads before the program exits. - assert(cnt > 0 && cnt <= MAX_THREADS); +void ThreadPool::exit() { - activeThreads = cnt; + for (size_t i = 0; i < threads.size(); i++) + delete threads[i]; - for (int i = 1; i < MAX_THREADS; i++) // Ignore main thread - 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. - threads[i].pawnTable.init(); - threads[i].materialTable.init(); - - threads[i].do_sleep = false; - } - else - threads[i].do_sleep = true; + delete timer; } -// init() is called during startup. Initializes locks and condition variables -// and launches all threads sending them immediately to sleep. +// read_uci_options() updates internal threads parameters from the corresponding +// UCI options and creates/destroys threads to match the requested number. Thread +// objects are dynamically allocated to avoid creating in advance all possible +// threads, with included pawns and material tables, if only few are used. -void ThreadsManager::init() { +void ThreadPool::read_uci_options() { - // Initialize sleep condition and lock used by thread manager - cond_init(sleepCond); - lock_init(threadsLock); - - // Initialize thread's sleep conditions and split point locks - for (int i = 0; i <= MAX_THREADS; i++) - { - lock_init(threads[i].sleepLock); - cond_init(threads[i].sleepCond); + maxThreadsPerSplitPoint = Options["Max Threads per Split Point"]; + minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; + useSleepingThreads = Options["Use Sleeping Threads"]; + size_t requested = Options["Threads"]; - for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) - lock_init(threads[i].splitPoints[j].lock); - } + assert(requested > 0); - // Allocate main thread tables to call evaluate() also when not searching - threads[0].pawnTable.init(); - threads[0].materialTable.init(); + while (threads.size() < requested) + threads.push_back(new Thread(&Thread::idle_loop)); - // Create and launch all the threads, threads will go immediately to sleep - for (int i = 0; i <= MAX_THREADS; i++) + while (threads.size() > requested) { - threads[i].is_searching = false; - threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking() - threads[i].threadID = i; - - bool ok = thread_create(threads[i].handle, start_routine, threads[i]); - - if (!ok) - { - std::cerr << "Failed to create thread number " << i << std::endl; - ::exit(EXIT_FAILURE); - } + delete threads.back(); + threads.pop_back(); } } -// exit() is called to cleanly terminate the threads when the program finishes +// wake_up() is called before a new search to start the threads that are waiting +// on the sleep condition and to reset maxPly. When useSleepingThreads is set +// threads will be woken up at split time. -void ThreadsManager::exit() { +void ThreadPool::wake_up() const { - for (int i = 0; i <= MAX_THREADS; i++) + for (size_t i = 0; i < threads.size(); i++) { - threads[i].do_terminate = true; // Search must be already finished - threads[i].wake_up(); - - thread_join(threads[i].handle); // Wait for thread termination - - // Now we can safely destroy associated locks and wait conditions - lock_destroy(threads[i].sleepLock); - cond_destroy(threads[i].sleepCond); + threads[i]->maxPly = 0; + threads[i]->do_sleep = false; - for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) - lock_destroy(threads[i].splitPoints[j].lock); + if (!useSleepingThreads) + threads[i]->wake_up(); } - - lock_destroy(threadsLock); - cond_destroy(sleepCond); } -// available_slave_exists() tries to find an idle thread which is available as -// a slave for the thread with threadID 'master'. - -bool ThreadsManager::available_slave_exists(int master) const { +// sleep() is called after the search finishes to ask all the threads but the +// main one to go waiting on a sleep condition. - assert(master >= 0 && master < activeThreads); - - for (int i = 0; i < activeThreads; i++) - if (threads[i].is_available_to(master)) - return true; +void ThreadPool::sleep() const { - return false; + // Main thread will go to sleep by itself to avoid a race with start_searching() + for (size_t i = 1; i < threads.size(); i++) + threads[i]->do_sleep = true; } -// split_point_finished() checks if all the slave threads of a given split -// point have finished searching. +// available_slave_exists() tries to find an idle thread which is available as +// a slave for the thread 'master'. -bool ThreadsManager::split_point_finished(SplitPoint* sp) const { +bool ThreadPool::available_slave_exists(Thread* master) const { - for (int i = 0; i < activeThreads; i++) - if (sp->is_slave[i]) - return false; + for (size_t i = 0; i < threads.size(); i++) + if (threads[i]->is_available_to(master)) + return true; - return true; + return false; } @@ -250,251 +283,154 @@ bool ThreadsManager::split_point_finished(SplitPoint* sp) const { // search(). When all threads have returned from search() then split() returns. template -Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta, - Value bestValue, Depth depth, Move threatMove, - int moveCount, MovePicker* mp, int nodeType) { +Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta, + Value bestValue, Move* bestMove, Depth depth, + Move threatMove, int moveCount, MovePicker* mp, int nodeType) { + assert(pos.pos_is_ok()); 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); - assert(activeThreads > 1); - int i, master = pos.thread(); - Thread& masterThread = threads[master]; + Thread* master = pos.this_thread(); - // If we already have too many active split points, don't split - if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) + if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD) return bestValue; // Pick the next available split point from the split point stack - SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints]; - - // Initialize the split point - 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++) - sp->is_slave[i] = false; - - // If we are here it means we are not available - assert(masterThread.is_searching); - - int workersCnt = 1; // At least the master is included + SplitPoint& sp = master->splitPoints[master->splitPointsCnt]; + + sp.parent = master->curSplitPoint; + sp.master = master; + sp.cutoff = false; + sp.slavesMask = 1ULL << master->idx; + sp.depth = depth; + sp.bestMove = *bestMove; + 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; + + assert(master->is_searching); + + master->curSplitPoint = &sp; + int slavesCnt = 0; // Try to allocate available threads and ask them to start searching setting // is_searching flag. This must be done under lock protection to avoid concurrent // allocation of the same slave by another master. - lock_grab(threadsLock); + sp.mutex.lock(); + mutex.lock(); - for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++) - if (threads[i].is_available_to(master)) + for (size_t i = 0; i < threads.size() && !Fake; ++i) + if (threads[i]->is_available_to(master)) { - workersCnt++; - sp->is_slave[i] = true; - threads[i].splitPoint = sp; - - // This makes the slave to exit from idle_loop() - threads[i].is_searching = true; + sp.slavesMask |= 1ULL << i; + threads[i]->curSplitPoint = &sp; + threads[i]->is_searching = true; // Slave leaves idle_loop() if (useSleepingThreads) - threads[i].wake_up(); + threads[i]->wake_up(); + + if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included + break; } - lock_release(threadsLock); + master->splitPointsCnt++; - // We failed to allocate even one slave, return - if (!Fake && workersCnt == 1) - return bestValue; - - masterThread.splitPoint = sp; - masterThread.activeSplitPoints++; + mutex.unlock(); + sp.mutex.unlock(); // 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 + // The thread will return from the idle loop when all slaves have finished // their work at this split point. - masterThread.idle_loop(sp); + if (slavesCnt || Fake) + { + master->idle_loop(); - // 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(!masterThread.is_searching); + // 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(!master->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.is_searching = true; - masterThread.activeSplitPoints--; + // finished. Note that setting is_searching and decreasing splitPointsCnt is + // done under lock protection to avoid a race with Thread::is_available_to(). + sp.mutex.lock(); // To protect sp.nodes + mutex.lock(); - lock_release(threadsLock); + master->is_searching = true; + master->splitPointsCnt--; + master->curSplitPoint = sp.parent; + pos.set_nodes_searched(pos.nodes_searched() + sp.nodes); + *bestMove = sp.bestMove; - masterThread.splitPoint = sp->parent; - pos.set_nodes_searched(pos.nodes_searched() + sp->nodes); + mutex.unlock(); + sp.mutex.unlock(); - return sp->bestValue; + return sp.bestValue; } // Explicit template instantiations -template Value ThreadsManager::split(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int); -template Value ThreadsManager::split(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int); +template Value ThreadPool::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int); +template Value ThreadPool::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int); -// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and -// then calls do_timer_event(). If maxPly is 0 thread sleeps until is woken up. -extern void check_time(); +// set_timer() is used to set the timer to trigger after msec milliseconds. +// If msec is 0 then timer is stopped. -void Thread::timer_loop() { +void ThreadPool::set_timer(int msec) { - while (!do_terminate) - { - lock_grab(sleepLock); - timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX); - lock_release(sleepLock); - check_time(); - } + timer->mutex.lock(); + timer->maxPly = msec; + timer->sleepCondition.notify_one(); // Wake up and restart the timer + timer->mutex.unlock(); } -// ThreadsManager::set_timer() is used to set the timer to trigger after msec -// milliseconds. If msec is 0 then timer is stopped. +// wait_for_search_finished() waits for main thread to go to sleep, this means +// search is finished. Then returns. -void ThreadsManager::set_timer(int msec) { +void ThreadPool::wait_for_search_finished() { - Thread& timer = threads[MAX_THREADS]; - - lock_grab(timer.sleepLock); - timer.maxPly = msec; - cond_signal(timer.sleepCond); // Wake up and restart the timer - lock_release(timer.sleepLock); + Thread* t = main_thread(); + t->mutex.lock(); + t->sleepCondition.notify_one(); // In case is waiting for stop or ponderhit + while (!t->do_sleep) sleepCondition.wait(t->mutex); + t->mutex.unlock(); } -// Thread::main_loop() is where the main thread is parked waiting to be started -// when there is a new search. Main thread will launch all the slave threads. - -void Thread::main_loop() { - - while (true) - { - lock_grab(sleepLock); - - do_sleep = true; // Always return to sleep after a search - is_searching = false; - - while (do_sleep && !do_terminate) - { - cond_signal(Threads.sleepCond); // Wake up UI thread if needed - cond_wait(sleepCond, sleepLock); - } +// start_searching() wakes up the main thread sleeping in main_loop() so to start +// a new search, then returns immediately. - is_searching = true; +void ThreadPool::start_searching(const Position& pos, const LimitsType& limits, + const std::vector& searchMoves, StateStackPtr& states) { + wait_for_search_finished(); - lock_release(sleepLock); - - if (do_terminate) - return; + SearchTime = Time::current_time(); // As early as possible - Search::think(); - } -} - - -// ThreadsManager::start_thinking() is used by UI thread to wake up the main -// thread parked in main_loop() and starting a new search. If asyncMode is true -// then function returns immediately, otherwise caller is blocked waiting for -// the search to finish. - -void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits, - const std::set& searchMoves, bool async) { - Thread& main = threads[0]; - - lock_grab(main.sleepLock); - - // Wait main thread has finished before to launch a new search - while (!main.do_sleep) - cond_wait(sleepCond, main.sleepLock); + Signals.stopOnPonderhit = Signals.firstRootMove = false; + Signals.stop = Signals.failedLowAtRoot = false; - // Copy input arguments to initialize the search - RootPosition.copy(pos, 0); + RootPosition = pos; Limits = limits; + SetupStates = states; // Ownership transfer here RootMoves.clear(); - // Populate RootMoves with all the legal moves (default) or, if a searchMoves - // set is given, with the subset of legal moves to search. - for (MoveList ml(pos); !ml.end(); ++ml) - if (searchMoves.empty() || searchMoves.count(ml.move())) + for (MoveList ml(pos); !ml.end(); ++ml) + if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move())) RootMoves.push_back(RootMove(ml.move())); - // Reset signals before to start the new search - Signals.stopOnPonderhit = Signals.firstRootMove = false; - Signals.stop = Signals.failedLowAtRoot = false; - - main.do_sleep = false; - cond_signal(main.sleepCond); // Wake up main thread and start searching - - if (!async) - while (!main.do_sleep) - cond_wait(sleepCond, main.sleepLock); - - lock_release(main.sleepLock); -} - - -// ThreadsManager::stop_thinking() is used by UI thread to raise a stop request -// and to wait for the main thread finishing the search. Needed to wait exiting -// and terminate the threads after a 'quit' command. - -void ThreadsManager::stop_thinking() { - - Thread& main = threads[0]; - - Search::Signals.stop = true; - - lock_grab(main.sleepLock); - - cond_signal(main.sleepCond); // In case is waiting for stop or ponderhit - - while (!main.do_sleep) - cond_wait(sleepCond, main.sleepLock); - - lock_release(main.sleepLock); -} - - -// ThreadsManager::wait_for_stop_or_ponderhit() is called when the maximum depth -// is reached while the program is pondering. The point is to work around a wrinkle -// in the UCI protocol: When pondering, the engine is not allowed to give a -// "bestmove" before the GUI sends it a "stop" or "ponderhit" command. We simply -// wait here until one of these commands (that raise StopRequest) is sent and -// then return, after which the bestmove and pondermove will be printed. - -void ThreadsManager::wait_for_stop_or_ponderhit() { - - Signals.stopOnPonderhit = true; - - Thread& main = threads[0]; - - lock_grab(main.sleepLock); - - while (!Signals.stop) - cond_wait(main.sleepCond, main.sleepLock); - - lock_release(main.sleepLock); + main_thread()->do_sleep = false; + main_thread()->wake_up(); }