X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=cb3f8223aacf26a93199c7c2ed6cef1b8a02916c;hp=8a8e7199d43e00c42b3c5405ea95ace53af93d40;hb=676b2c8435502409145491f2f86454f11f99dae8;hpb=51e8efdab5f62ebc23e4f7adaea96f619cbca194 diff --git a/src/thread.cpp b/src/thread.cpp index 8a8e7199..cb3f8223 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -32,35 +32,107 @@ ThreadsManager 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(_WIN32) || defined(_WIN64) - 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; - if (th->threadID == 0) - th->main_loop(); +// 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. - else if (th->threadID == MAX_THREADS) - th->timer_loop(); +Thread::Thread(Fn fn) { - else - th->idle_loop(NULL); + is_searching = do_exit = false; + maxPly = splitPointsCnt = 0; + curSplitPoint = NULL; + start_fn = fn; + idx = Threads.size(); - return 0; + do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching() + + lock_init(sleepLock); + cond_init(sleepCond); + + for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++) + lock_init(splitPoints[j].lock); + + 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() { -// 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. + assert(do_sleep); + + do_exit = true; // Search must be already finished + wake_up(); + + thread_join(handle); // Wait for thread termination + + lock_destroy(sleepLock); + cond_destroy(sleepCond); + + for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++) + lock_destroy(splitPoints[j].lock); +} + + +// 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) + { + lock_grab(sleepLock); + timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX); + lock_release(sleepLock); + 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) + { + lock_grab(sleepLock); + + do_sleep = true; // Always return to sleep after a search + is_searching = false; + + while (do_sleep && !do_exit) + { + cond_signal(Threads.sleepCond); // Wake up UI thread if needed + cond_wait(sleepCond, sleepLock); + } + + lock_release(sleepLock); + + if (do_exit) + return; + + is_searching = true; + + Search::think(); + } +} + + +// 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() { @@ -70,150 +142,145 @@ void Thread::wake_up() { } -// cutoff_occurred() checks whether a beta cutoff has occurred in the current -// active split point, or in some ancestor of the split point. +// 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; + + lock_grab(sleepLock); + while (!Signals.stop) cond_wait(sleepCond, sleepLock); + lock_release(sleepLock); +} + + +// 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 sp_count = 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. - return !sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master)); + 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() { - - maxThreadsPerSplitPoint = Options["Max Threads per Split Point"]; - minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; - useSleepingThreads = Options["Use Sleeping Threads"]; +void ThreadsManager::init() { - set_size(Options["Threads"]); + cond_init(sleepCond); + lock_init(splitLock); + 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) { +// d'tor cleanly terminates the threads when the program exits. - assert(cnt > 0 && cnt <= MAX_THREADS); +ThreadsManager::~ThreadsManager() { - activeThreads = cnt; + for (int i = 0; i < 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; + lock_destroy(splitLock); + cond_destroy(sleepCond); } -// init() is called during startup. Initializes locks and condition variables -// and launches all threads sending them immediately to sleep. - -void ThreadsManager::init() { +// 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. - cond_init(sleepCond); - lock_init(splitLock); +void ThreadsManager::read_uci_options() { - 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"]; + int 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 (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 (size() > requested) { - threads[i].is_searching = false; - threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking() - threads[i].threadID = i; - - if (!thread_create(threads[i].handle, start_routine, threads[i])) - { - 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 ThreadsManager::wake_up() const { - assert(threads[0].is_searching == false); - - for (int i = 0; i <= MAX_THREADS; i++) + for (int i = 0; i < size(); i++) { - threads[i].do_exit = true; // Search must be already finished - threads[i].wake_up(); + threads[i]->maxPly = 0; + threads[i]->do_sleep = false; - thread_join(threads[i].handle); // Wait for thread termination + if (!useSleepingThreads) + threads[i]->wake_up(); + } +} - lock_destroy(threads[i].sleepLock); - cond_destroy(threads[i].sleepCond); - for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) - lock_destroy(threads[i].splitPoints[j].lock); - } +// sleep() is called after the search finishes to ask all the threads but the +// main one to go waiting on a sleep condition. - lock_destroy(splitLock); - cond_destroy(sleepCond); +void ThreadsManager::sleep() const { + + for (int i = 1; i < size(); i++) // Main thread will go to sleep by itself + threads[i]->do_sleep = true; // to avoid a race with start_searching() } // 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 { +// a slave for the thread 'master'. - assert(master >= 0 && master < activeThreads); +bool ThreadsManager::available_slave_exists(Thread* master) const { - for (int i = 0; i < activeThreads; i++) - if (threads[i].is_available_to(master)) + for (int i = 0; i < size(); i++) + if (threads[i]->is_available_to(master)) return true; return false; @@ -231,31 +298,29 @@ bool ThreadsManager::available_slave_exists(int master) const { 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 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 master = pos.thread(); - Thread& masterThread = threads[master]; + Thread* master = pos.this_thread(); - 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]; + SplitPoint* sp = &master->splitPoints[master->splitPointsCnt++]; - sp->parent = masterThread.splitPoint; + sp->parent = master->curSplitPoint; sp->master = master; - sp->is_betaCutoff = false; - sp->slavesMask = 1ULL << master; + sp->cutoff = false; + sp->slavesMask = 1ULL << master->idx; sp->depth = depth; + sp->bestMove = *bestMove; sp->threatMove = threatMove; sp->alpha = alpha; sp->beta = beta; @@ -267,35 +332,33 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta, sp->nodes = 0; sp->ss = ss; - assert(masterThread.is_searching); + 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(sp->lock); lock_grab(splitLock); - lock_grab(sp->lock); // To protect sp->slaves_mask - for (int i = 0; i < activeThreads && !Fake; i++) - if (threads[i].is_available_to(master)) + for (int i = 0; i < size() && !Fake; ++i) + if (threads[i]->is_available_to(master)) { sp->slavesMask |= 1ULL << i; - threads[i].splitPoint = sp; - threads[i].is_searching = true; // Slave leaves idle_loop() + 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; } - masterThread.splitPoint = sp; - masterThread.activeSplitPoints++; - - lock_release(sp->lock); lock_release(splitLock); + lock_release(sp->lock); // 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. @@ -303,44 +366,35 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta, // the thread will return from the idle loop when all slaves have finished // their work at this split point. if (slavesCnt || Fake) - masterThread.idle_loop(sp); + { + master->idle_loop(sp); + + // 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 setting is_searching and decreasing activeSplitPoints is + // finished. Note that setting is_searching and decreasing splitPointsCnt is // done under lock protection to avoid a race with Thread::is_available_to(). - lock_grab(splitLock); lock_grab(sp->lock); // To protect sp->nodes + lock_grab(splitLock); - masterThread.is_searching = true; - masterThread.activeSplitPoints--; - masterThread.splitPoint = sp->parent; + master->is_searching = true; + master->splitPointsCnt--; + master->curSplitPoint = sp->parent; pos.set_nodes_searched(pos.nodes_searched() + sp->nodes); + *bestMove = sp->bestMove; - lock_release(sp->lock); lock_release(splitLock); + lock_release(sp->lock); 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); - - -// 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(); - -void Thread::timer_loop() { - - while (!do_exit) - { - lock_grab(sleepLock); - timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX); - lock_release(sleepLock); - check_time(); - } -} +template Value ThreadsManager::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int); +template Value ThreadsManager::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int); // ThreadsManager::set_timer() is used to set the timer to trigger after msec @@ -348,124 +402,46 @@ void Thread::timer_loop() { void ThreadsManager::set_timer(int msec) { - 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); + lock_grab(timer->sleepLock); + timer->maxPly = msec; + cond_signal(timer->sleepCond); // Wake up and restart the timer + lock_release(timer->sleepLock); } -// 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_exit) - { - cond_signal(Threads.sleepCond); // Wake up UI thread if needed - cond_wait(sleepCond, sleepLock); - } - - is_searching = true; - - lock_release(sleepLock); +// ThreadsManager::wait_for_search_finished() waits for main thread to go to +// sleep, this means search is finished. Then returns. - if (do_exit) - return; +void ThreadsManager::wait_for_search_finished() { - Search::think(); - } + Thread* t = main_thread(); + lock_grab(t->sleepLock); + cond_signal(t->sleepCond); // In case is waiting for stop or ponderhit + while (!t->do_sleep) cond_wait(sleepCond, t->sleepLock); + lock_release(t->sleepLock); } -// 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. +// ThreadsManager::start_searching() wakes up the main thread sleeping in +// main_loop() so to start a new search, then returns immediately. -void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits, - const std::set& searchMoves, bool async) { - Thread& main = threads[0]; +void ThreadsManager::start_searching(const Position& pos, const LimitsType& limits, + const std::vector& searchMoves) { + wait_for_search_finished(); - lock_grab(main.sleepLock); + SearchTime.restart(); // As early as possible - // 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; 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())) + 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(); }