X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=9aa0b55ef0deaafac39f430bbab900a754ba855f;hp=1f5dc82350e50bdfbcbf0bc578a239d3314b7ea4;hb=6950d07bf421b122ccb5a15a2ed4fa3a993d9609;hpb=99ae47716ac605286e60634632cb5eccac9a63ce diff --git a/src/thread.cpp b/src/thread.cpp index 1f5dc823..9aa0b55e 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -32,26 +32,23 @@ ThreadPool Threads; // Global object namespace { extern "C" { // start_routine() is the C function which is called when a new thread - // is launched. It is a wrapper to member function pointed by start_fn. + // is launched. It is a wrapper to the virtual function idle_loop(). - long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; } + long start_routine(Thread* th) { th->idle_loop(); return 0; } } } // 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. +// the the virtual function idle_loop(), going immediately to sleep. -Thread::Thread(Fn fn) : splitPoints() { +Thread::Thread() : splitPoints() { - is_searching = do_exit = false; - maxPly = splitPointsCnt = 0; - curSplitPoint = NULL; - start_fn = fn; + searching = exit = false; + maxPly = splitPointsSize = 0; + activeSplitPoint = NULL; idx = Threads.size(); - do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching() - if (!thread_create(handle, start_routine, this)) { std::cerr << "Failed to create thread number " << idx << std::endl; @@ -60,48 +57,49 @@ Thread::Thread(Fn fn) : splitPoints() { } -// Thread d'tor waits for thread termination before to return. +// Thread d'tor waits for thread termination before to return Thread::~Thread() { - assert(do_sleep); - - do_exit = true; // Search must be already finished + exit = true; // Search must be already finished notify_one(); 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. +// TimerThread::idle_loop() is where the timer thread waits msec milliseconds +// and then calls check_time(). If msec is 0 thread sleeps until is woken up. extern void check_time(); -void Thread::timer_loop() { +void TimerThread::idle_loop() { - while (!do_exit) + while (!exit) { mutex.lock(); - while (!maxPly && !do_exit) - sleepCondition.wait_for(mutex, maxPly ? maxPly : INT_MAX); + + if (!exit) + sleepCondition.wait_for(mutex, msec ? msec : INT_MAX); + mutex.unlock(); - check_time(); + + if (msec) + check_time(); } } -// Thread::main_loop() is where the main thread is parked waiting to be started +// MainThread::idle_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() { +void MainThread::idle_loop() { while (true) { mutex.lock(); - do_sleep = true; // Always return to sleep after a search - is_searching = false; + thinking = false; - while (do_sleep && !do_exit) + while (!thinking && !exit) { Threads.sleepCondition.notify_one(); // Wake up UI thread if needed sleepCondition.wait(mutex); @@ -109,20 +107,21 @@ void Thread::main_loop() { mutex.unlock(); - if (do_exit) + if (exit) return; - is_searching = true; + searching = true; Search::think(); - assert(is_searching); + assert(searching); + + searching = false; } } -// Thread::notify_one() wakes up the thread, normally at the beginning of the -// search or, if "sleeping threads" is used at split time. +// Thread::notify_one() wakes up the thread when there is some search to do void Thread::notify_one() { @@ -147,7 +146,7 @@ void Thread::wait_for(volatile const bool& b) { bool Thread::cutoff_occurred() const { - for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent) + for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parent) if (sp->cutoff) return true; @@ -158,43 +157,44 @@ bool Thread::cutoff_occurred() const { // 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). +// the master of some 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(Thread* master) const { - if (is_searching) + if (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 spCnt = splitPointsCnt; + int size = splitPointsSize; - // No active split points means that the thread is available as a slave for any + // No split points means that the thread is available as a slave for any // other thread otherwise apply the "helpful master" concept if possible. - return !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx)); + return !size || (splitPoints[size - 1].slavesMask & (1ULL << master->idx)); } -// init() is called at startup. Initializes lock and condition variable and -// launches requested threads sending them immediately to sleep. We cannot use +// init() is called at startup to create and launch requested threads, that will +// go immediately to sleep due to 'sleepWhileIdle' set to true. 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. +// engine at this point due to allocation of Endgames in Thread c'tor. void ThreadPool::init() { - timer = new Thread(&Thread::timer_loop); - threads.push_back(new Thread(&Thread::main_loop)); + sleepWhileIdle = true; + timer = new TimerThread(); + threads.push_back(new MainThread()); read_uci_options(); } -// exit() cleanly terminates the threads before the program exits. +// exit() cleanly terminates the threads before the program exits void ThreadPool::exit() { - delete timer; // As first becuase check_time() accesses threads data + delete timer; // As first because check_time() accesses threads data for (size_t i = 0; i < threads.size(); i++) delete threads[i]; @@ -210,13 +210,12 @@ void ThreadPool::read_uci_options() { maxThreadsPerSplitPoint = Options["Max Threads per Split Point"]; minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; - useSleepingThreads = Options["Use Sleeping Threads"]; size_t requested = Options["Threads"]; assert(requested > 0); while (threads.size() < requested) - threads.push_back(new Thread(&Thread::idle_loop)); + threads.push_back(new Thread()); while (threads.size() > requested) { @@ -226,10 +225,10 @@ void ThreadPool::read_uci_options() { } -// available_slave_exists() tries to find an idle thread which is available as -// a slave for the thread 'master'. +// slave_available() tries to find an idle thread which is available as a slave +// for the thread 'master'. -bool ThreadPool::available_slave_exists(Thread* master) const { +bool ThreadPool::slave_available(Thread* master) const { for (size_t i = 0; i < threads.size(); i++) if (threads[i]->is_available_to(master)) @@ -241,12 +240,12 @@ bool ThreadPool::available_slave_exists(Thread* master) const { // 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 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. +// (because no idle threads are available), 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 ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta, @@ -254,23 +253,20 @@ Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta, int moveCount, MovePicker& mp, int nodeType) { assert(pos.pos_is_ok()); + assert(bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE); assert(bestValue > -VALUE_INFINITE); - assert(bestValue <= alpha); - assert(alpha < beta); - assert(beta <= VALUE_INFINITE); - assert(depth > DEPTH_ZERO); + assert(depth >= Threads.minimumSplitDepth); Thread* master = pos.this_thread(); - if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD) - return bestValue; + assert(master->searching); + assert(master->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD); // Pick the next available split point from the split point stack - SplitPoint& sp = master->splitPoints[master->splitPointsCnt]; + SplitPoint& sp = master->splitPoints[master->splitPointsSize]; - sp.parent = master->curSplitPoint; sp.master = master; - sp.cutoff = false; + sp.parent = master->activeSplitPoint; sp.slavesMask = 1ULL << master->idx; sp.depth = depth; sp.bestMove = *bestMove; @@ -283,60 +279,54 @@ Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta, sp.moveCount = moveCount; sp.pos = &pos; sp.nodes = 0; + sp.cutoff = false; 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 + // 'searching' flag. This must be done under lock protection to avoid concurrent // allocation of the same slave by another master. mutex.lock(); sp.mutex.lock(); + master->splitPointsSize++; + master->activeSplitPoint = &sp; + + size_t slavesCnt = 1; // Master is always included + for (size_t i = 0; i < threads.size() && !Fake; ++i) - if (threads[i]->is_available_to(master)) + if (threads[i]->is_available_to(master) && ++slavesCnt <= maxThreadsPerSplitPoint) { sp.slavesMask |= 1ULL << i; - threads[i]->curSplitPoint = &sp; - threads[i]->is_searching = true; // Slave leaves idle_loop() - - if (useSleepingThreads) - threads[i]->notify_one(); - - if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included - break; + threads[i]->activeSplitPoint = &sp; + threads[i]->searching = true; // Slave leaves idle_loop() + threads[i]->notify_one(); // Could be sleeping } - master->splitPointsCnt++; - sp.mutex.unlock(); 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. + // it will instantly launch a search, because its 'searching' flag is set. // The thread will return from the idle loop when all slaves have finished // their work at this split point. - if (slavesCnt || Fake) + if (slavesCnt > 1 || Fake) { - master->idle_loop(); + master->Thread::idle_loop(); // Force a call to base class 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(!master->is_searching); + assert(!master->searching); } // We have returned from the idle loop, which means that all threads are - // finished. Note that setting is_searching and decreasing splitPointsCnt is + // finished. Note that setting 'searching' and decreasing splitPointsSize is // done under lock protection to avoid a race with Thread::is_available_to(). mutex.lock(); sp.mutex.lock(); - master->is_searching = true; - master->splitPointsCnt--; - master->curSplitPoint = sp.parent; + master->searching = true; + master->splitPointsSize--; + master->activeSplitPoint = sp.parent; pos.set_nodes_searched(pos.nodes_searched() + sp.nodes); *bestMove = sp.bestMove; @@ -351,24 +341,23 @@ template Value ThreadPool::split(Position&, Stack*, Value, Value, Value, template Value ThreadPool::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int); -// wait_for_search_finished() waits for main thread to go to sleep, this means -// search is finished. Then returns. +// wait_for_think_finished() waits for main thread to go to sleep then returns -void ThreadPool::wait_for_search_finished() { +void ThreadPool::wait_for_think_finished() { - Thread* t = main_thread(); + MainThread* t = main_thread(); t->mutex.lock(); - while (!t->do_sleep) sleepCondition.wait(t->mutex); + while (t->thinking) sleepCondition.wait(t->mutex); t->mutex.unlock(); } -// start_searching() wakes up the main thread sleeping in main_loop() so to start +// start_thinking() wakes up the main thread sleeping in main_loop() so to start // a new search, then returns immediately. -void ThreadPool::start_searching(const Position& pos, const LimitsType& limits, - const std::vector& searchMoves, StateStackPtr& states) { - wait_for_search_finished(); +void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, + const std::vector& searchMoves, StateStackPtr& states) { + wait_for_think_finished(); SearchTime = Time::now(); // As early as possible @@ -384,6 +373,6 @@ void ThreadPool::start_searching(const Position& pos, const LimitsType& limits, if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move())) RootMoves.push_back(RootMove(ml.move())); - main_thread()->do_sleep = false; - main_thread()->notify_one(); + main_thread()->thinking = true; + main_thread()->notify_one(); // Starts main thread }