/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, 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
*/
#include <cassert>
-#include <iostream>
+#include <algorithm> // For std::count
#include "movegen.h"
#include "search.h"
#include "thread.h"
-#include "ucioption.h"
-
-using namespace Search;
+#include "uci.h"
+#include "syzygy/tbprobe.h"
+#include "tt.h"
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.
-
- long start_routine(Thread* th) { (th->*(th->start_fn))(); 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.
+/// Thread constructor launches the thread and waits until it goes to sleep
+/// in idle_loop(). Note that 'searching' and 'exit' should be already set.
-Thread::Thread(Fn fn) {
+Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
- is_searching = do_exit = false;
- maxPly = splitPointsCnt = 0;
- curSplitPoint = NULL;
- start_fn = fn;
- 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;
- ::exit(EXIT_FAILURE);
- }
+ wait_for_search_finished();
}
-// Thread d'tor waits for thread termination before to return.
+/// Thread destructor wakes up the thread in idle_loop() and waits
+/// for its termination. Thread should be already waiting.
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);
- }
-}
-
-
-// Thread::wake_up() wakes up the thread, normally at the beginning of the search
-// or, if "sleeping threads" is used at split time.
+ assert(!searching);
-void Thread::wake_up() {
-
- mutex.lock();
- sleepCondition.notify_one();
- mutex.unlock();
+ exit = true;
+ start_searching();
+ stdThread.join();
}
+/// Thread::bestMoveCount(Move move) return best move counter for the given root move
-// 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() {
+int Thread::best_move_count(Move move) {
- Signals.stopOnPonderhit = true;
+ auto rm = std::find(rootMoves.begin() + pvIdx,
+ rootMoves.begin() + pvLast, move);
- mutex.lock();
- while (!Signals.stop) sleepCondition.wait(mutex);;
- mutex.unlock();
+ return rm != rootMoves.begin() + pvLast ? rm->bestMoveCount : 0;
}
+/// Thread::clear() reset histories, usually before a new game
-// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the
-// current active split point, or in some ancestor of the split point.
+void Thread::clear() {
-bool Thread::cutoff_occurred() const {
+ counterMoves.fill(MOVE_NONE);
+ mainHistory.fill(0);
+ captureHistory.fill(0);
- for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent)
- if (sp->cutoff)
- return true;
+ for (bool inCheck : { false, true })
+ for (StatsType c : { NoCaptures, Captures })
+ for (auto& to : continuationHistory[inCheck][c])
+ for (auto& h : to)
+ h->fill(0);
- return false;
+ for (bool inCheck : { false, true })
+ for (StatsType c : { NoCaptures, Captures })
+ continuationHistory[inCheck][c][NO_PIECE][0]->fill(Search::CounterMovePruneThreshold - 1);
}
+/// Thread::start_searching() wakes up the thread that will start the search
-// 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(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 spCnt = splitPointsCnt;
+void Thread::start_searching() {
- // 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 !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx));
+ std::lock_guard<std::mutex> lk(mutex);
+ searching = true;
+ cv.notify_one(); // Wake up the thread in idle_loop()
}
-// 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.
+/// Thread::wait_for_search_finished() blocks on the condition variable
+/// until the thread has finished searching.
-void ThreadPool::init() {
+void Thread::wait_for_search_finished() {
- timer = new Thread(&Thread::timer_loop);
- threads.push_back(new Thread(&Thread::main_loop));
- read_uci_options();
+ std::unique_lock<std::mutex> lk(mutex);
+ cv.wait(lk, [&]{ return !searching; });
}
-// d'tor cleanly terminates the threads when the program exits.
-
-ThreadPool::~ThreadPool() {
-
- for (size_t i = 0; i < threads.size(); i++)
- delete threads[i];
-
- delete timer;
-}
-
+/// Thread::idle_loop() is where the thread is parked, blocked on the
+/// condition variable, when it has no work to do.
-// 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 Thread::idle_loop() {
-void ThreadPool::read_uci_options() {
+ // If OS already scheduled us on a different group than 0 then don't overwrite
+ // the choice, eventually we are one of many one-threaded processes running on
+ // some Windows NUMA hardware, for instance in fishtest. To make it simple,
+ // just check if running threads are below a threshold, in this case all this
+ // NUMA machinery is not needed.
+ if (Options["Threads"] > 8)
+ WinProcGroup::bindThisThread(idx);
- 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));
-
- while (threads.size() > requested)
+ while (true)
{
- delete threads.back();
- threads.pop_back();
- }
-}
-
+ std::unique_lock<std::mutex> lk(mutex);
+ searching = false;
+ cv.notify_one(); // Wake up anyone waiting for search finished
+ cv.wait(lk, [&]{ return searching; });
-// 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.
+ if (exit)
+ return;
-void ThreadPool::wake_up() const {
+ lk.unlock();
- for (size_t i = 0; i < threads.size(); i++)
- {
- threads[i]->maxPly = 0;
- threads[i]->do_sleep = false;
-
- if (!useSleepingThreads)
- threads[i]->wake_up();
+ search();
}
}
+/// ThreadPool::set() creates/destroys threads to match the requested number.
+/// Created and launched threads will immediately go to sleep in idle_loop.
+/// Upon resizing, threads are recreated to allow for binding if necessary.
-// sleep() is called after the search finishes to ask all the threads but the
-// main one to go waiting on a sleep condition.
-
-void ThreadPool::sleep() const {
-
- // 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;
-}
-
-
-// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread 'master'.
-
-bool ThreadPool::available_slave_exists(Thread* master) const {
-
- for (size_t i = 0; i < threads.size(); i++)
- if (threads[i]->is_available_to(master))
- return true;
-
- return false;
-}
-
+void ThreadPool::set(size_t requested) {
-// 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.
-
-template <bool Fake>
-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);
-
- Thread* master = pos.this_thread();
-
- if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
- return bestValue;
-
- // Pick the next available split point from the split point stack
- 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.
- sp.mutex.lock();
- mutex.lock();
-
- for (size_t i = 0; i < threads.size() && !Fake; ++i)
- if (threads[i]->is_available_to(master))
- {
- sp.slavesMask |= 1ULL << i;
- threads[i]->curSplitPoint = &sp;
- threads[i]->is_searching = true; // Slave leaves idle_loop()
-
- if (useSleepingThreads)
- threads[i]->wake_up();
-
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
- break;
- }
-
- master->splitPointsCnt++;
-
- 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.
- // The thread will return from the idle loop when all slaves have finished
- // their work at this split point.
- if (slavesCnt || Fake)
- {
- master->idle_loop();
+ if (size() > 0) { // destroy any existing thread(s)
+ main()->wait_for_search_finished();
- // 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);
+ while (size() > 0)
+ delete back(), pop_back();
}
- // We have returned from the idle loop, which means that all threads are
- // 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();
+ if (requested > 0) { // create new thread(s)
+ push_back(new MainThread(0));
- master->is_searching = true;
- master->splitPointsCnt--;
- master->curSplitPoint = sp.parent;
- pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
- *bestMove = sp.bestMove;
+ while (size() < requested)
+ push_back(new Thread(size()));
+ clear();
- mutex.unlock();
- sp.mutex.unlock();
+ // Reallocate the hash with the new threadpool size
+ TT.resize(Options["Hash"]);
- return sp.bestValue;
+ // Init thread number dependent search params.
+ Search::init();
+ }
}
-// Explicit template instantiations
-template Value ThreadPool::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
-template Value ThreadPool::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
-
+/// ThreadPool::clear() sets threadPool data to initial values.
-// set_timer() is used to set the timer to trigger after msec milliseconds.
-// If msec is 0 then timer is stopped.
+void ThreadPool::clear() {
-void ThreadPool::set_timer(int msec) {
+ for (Thread* th : *this)
+ th->clear();
- timer->mutex.lock();
- timer->maxPly = msec;
- timer->sleepCondition.notify_one(); // Wake up and restart the timer
- timer->mutex.unlock();
+ main()->callsCnt = 0;
+ main()->previousScore = VALUE_INFINITE;
+ main()->previousTimeReduction = 1.0;
}
+/// ThreadPool::start_thinking() wakes up main thread waiting in idle_loop() and
+/// returns immediately. Main thread will wake up other threads and start the search.
-// wait_for_search_finished() waits for main thread to go to sleep, this means
-// search is finished. Then returns.
+void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
+ const Search::LimitsType& limits, bool ponderMode) {
-void ThreadPool::wait_for_search_finished() {
+ main()->wait_for_search_finished();
- 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();
-}
+ main()->stopOnPonderhit = stop = false;
+ main()->ponder = ponderMode;
+ Search::Limits = limits;
+ Search::RootMoves rootMoves;
+ for (const auto& m : MoveList<LEGAL>(pos))
+ if ( limits.searchmoves.empty()
+ || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+ rootMoves.emplace_back(m);
-// start_searching() wakes up the main thread sleeping in main_loop() so to start
-// a new search, then returns immediately.
+ if (!rootMoves.empty())
+ Tablebases::rank_root_moves(pos, rootMoves);
-void ThreadPool::start_searching(const Position& pos, const LimitsType& limits,
- const std::vector<Move>& searchMoves, StateStackPtr& states) {
- wait_for_search_finished();
+ // After ownership transfer 'states' becomes empty, so if we stop the search
+ // and call 'go' again without setting a new position states.get() == NULL.
+ assert(states.get() || setupStates.get());
- SearchTime.restart(); // As early as possible
+ if (states.get())
+ setupStates = std::move(states); // Ownership transfer, states is now empty
- Signals.stopOnPonderhit = Signals.firstRootMove = false;
- Signals.stop = Signals.failedLowAtRoot = false;
+ // We use Position::set() to set root position across threads. But there are
+ // some StateInfo fields (previous, pliesFromNull, capturedPiece) that cannot
+ // be deduced from a fen string, so set() clears them and to not lose the info
+ // we need to backup and later restore setupStates->back(). Note that setupStates
+ // is shared by threads but is accessed in read-only mode.
+ StateInfo tmp = setupStates->back();
- RootPosition = pos;
- Limits = limits;
- SetupStates = states; // Ownership transfer here
- RootMoves.clear();
+ for (Thread* th : *this)
+ {
+ th->nodes = th->tbHits = th->nmpMinPly = 0;
+ th->rootDepth = th->completedDepth = 0;
+ th->rootMoves = rootMoves;
+ th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
+ }
- for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
- RootMoves.push_back(RootMove(ml.move()));
+ setupStates->back() = tmp;
- main_thread()->do_sleep = false;
- main_thread()->wake_up();
+ main()->start_searching();
}
projects / stockfish / blobdiff