X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=1db61a20671e77376de2c7501175f2699f02b1c3;hp=20a431b4c2fc52fe0a2de966387eeca8910977ae;hb=103b368ab7f5fd696e0c6925917344d15a3c2d9c;hpb=dafd5b58642e70c3746fc90e467c35465eb65a00 diff --git a/src/thread.cpp b/src/thread.cpp index 20a431b4..1db61a20 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -19,36 +19,42 @@ #include +#include "movegen.h" +#include "search.h" #include "thread.h" #include "ucioption.h" -ThreadsManager Threads; // Global object definition +using namespace Search; + +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() with the supplied threadID. - // There are two versions of this function; one for POSIX threads and - // one for Windows threads. + // 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(). #if defined(_MSC_VER) + DWORD WINAPI start_routine(LPVOID thread) { +#else + void* start_routine(void* thread) { +#endif - DWORD WINAPI start_routine(LPVOID threadID) { + Thread* th = (Thread*)thread; - Threads.idle_loop(*(int*)threadID, NULL); - return 0; - } + if (th->threadID == 0) + th->main_loop(); -#else + else if (th->threadID == MAX_THREADS) + th->timer_loop(); - void* start_routine(void* threadID) { + else + th->idle_loop(NULL); - Threads.idle_loop(*(int*)threadID, NULL); - return NULL; + return 0; } -#endif - } } @@ -63,15 +69,15 @@ 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 { for (SplitPoint* sp = splitPoint; sp; sp = sp->parent) if (sp->is_betaCutoff) return true; + return false; } @@ -85,7 +91,7 @@ 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 @@ -102,41 +108,55 @@ bool Thread::is_available_to(int master) const { } -// read_uci_options() updates number of active threads and other internal -// parameters according to the UCI options values. It is called before -// to start a new search. +// 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. 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(); + maxThreadsPerSplitPoint = Options["Max Threads per Split Point"]; + minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; + useSleepingThreads = Options["Use Sleeping Threads"]; + + set_size(Options["Threads"]); } -// 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 = 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; +} - // Allocate pawn and material hash tables for main thread - init_hash_tables(); - // Initialize threads lock, used when allocating slaves during splitting +// init() is called during startup. Initializes locks and condition variables +// and launches all threads sending them immediately to sleep. + +void ThreadsManager::init() { + + // Initialize sleep condition and lock used by thread manager + cond_init(&sleepCond); lock_init(&threadsLock); - // Initialize sleep and split point locks - for (int i = 0; i < MAX_THREADS; i++) + // 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); @@ -145,27 +165,29 @@ void ThreadsManager::init() { lock_init(&(threads[i].splitPoints[j].lock)); } - // Create and startup all the threads but the main that is already running - for (int i = 1; i < MAX_THREADS; i++) + // Allocate main thread tables to call evaluate() also when not searching + threads[0].pawnTable.init(); + threads[0].materialTable.init(); + + // Create and launch all the threads, threads will go immediately to sleep + for (int i = 0; i <= MAX_THREADS; i++) { - threads[i].state = Thread::INITIALIZING; - threadID[i] = i; + threads[i].is_searching = false; + threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking() + 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, &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, &threads[i]); #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) {} } } @@ -174,19 +196,20 @@ void ThreadsManager::init() { void ThreadsManager::exit() { - // Force the woken up threads to exit idle_loop() and hence terminate - allThreadsShouldExit = true; - - for (int i = 0; i < MAX_THREADS; i++) + 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) {} - } + threads[i].do_terminate = true; // Search must be already finished + threads[i].wake_up(); - // Now we can safely destroy locks and wait conditions + // Wait for thread termination +#if defined(_MSC_VER) + WaitForSingleObject(threads[i].handle, INFINITE); + CloseHandle(threads[i].handle); +#else + pthread_join(threads[i].handle, NULL); +#endif + + // Now we can safely destroy associated locks and wait conditions lock_destroy(&threads[i].sleepLock); cond_destroy(&threads[i].sleepCond); @@ -195,55 +218,53 @@ void ThreadsManager::exit() { } lock_destroy(&threadsLock); -} - - -// 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(); - } + cond_destroy(&sleepCond); } // available_slave_exists() tries to find an idle thread which is available as -// a slave for the thread with threadID "master". +// a slave for the thread with threadID 'master'. bool ThreadsManager::available_slave_exists(int master) const { assert(master >= 0 && master < activeThreads); for (int i = 0; i < activeThreads; i++) - if (i != master && threads[i].is_available_to(master)) + if (threads[i].is_available_to(master)) return true; return false; } +// split_point_finished() checks if all the slave threads of a given split +// point have finished searching. + +bool ThreadsManager::split_point_finished(SplitPoint* sp) const { + + for (int i = 0; i < activeThreads; i++) + if (sp->is_slave[i]) + return false; + + return true; +} + + // split() does the actual work of distributing the work at a node between -// several available threads. If it does not succeed in splitting the -// node (because no idle threads are available, or because we have no unused -// split point objects), the function immediately returns. If splitting is -// possible, a SplitPoint object is initialized with all the data that must be -// copied to the helper threads and we tell our helper threads that they have -// been assigned work. This will cause them to instantly leave their idle loops and -// call search().When all threads have returned from search() then split() returns. +// several available threads. If it does not succeed in splitting the node +// (because no idle threads are available, or because we have no unused split +// point objects), the function immediately returns. If splitting is possible, a +// SplitPoint object is initialized with all the data that must be copied to the +// helper threads and then helper threads are told that they have been assigned +// work. This will cause them to instantly leave their idle loops and call +// search(). When all threads have returned from search() then split() returns. template -Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value beta, +Value ThreadsManager::split(Position& pos, Stack* 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(pos.pos_is_ok()); + assert(bestValue > -VALUE_INFINITE); assert(bestValue <= alpha); assert(alpha < beta); assert(beta <= VALUE_INFINITE); @@ -258,10 +279,10 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) return bestValue; - // Pick the next available split point object from the split point stack - SplitPoint* sp = masterThread.splitPoints + masterThread.activeSplitPoints; + // Pick the next available split point from the split point stack + SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints]; - // Initialize the split point object + // Initialize the split point sp->parent = masterThread.splitPoint; sp->master = master; sp->is_betaCutoff = false; @@ -276,28 +297,29 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b 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.state == Thread::SEARCHING); + assert(masterThread.is_searching); int workersCnt = 1; // At least the master is included // 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. + // is_searching flag. 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)) + 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].state = Thread::WORKISWAITING; + threads[i].is_searching = true; if (useSleepingThreads) threads[i].wake_up(); @@ -311,25 +333,24 @@ 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. - 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); + // 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); // 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); @@ -341,5 +362,149 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b } // Explicit template instantiations -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); +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_terminate) + { + lock_grab(&sleepLock); + timed_wait(&sleepCond, &sleepLock, maxPly ? maxPly : INT_MAX); + lock_release(&sleepLock); + check_time(); + } +} + + +// ThreadsManager::set_timer() is used to set the timer to trigger after msec +// milliseconds. If msec is 0 then timer is stopped. + +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); +} + + +// 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); + } + + is_searching = true; + + lock_release(&sleepLock); + + if (do_terminate) + return; + + 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); + + // Copy input arguments to initialize the search + RootPosition.copy(pos, 0); + 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())) + 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); +}