/*
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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-#include <algorithm> // For std::count
#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 the virtual function idle_loop().
-
- long start_routine(Thread* th) { th->idle_loop(); return 0; }
-} }
+/// 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(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
-// Thread c'tor starts a newly-created thread of execution that will call
-// the the virtual function idle_loop(), going immediately to sleep.
-
-Thread::Thread() : splitPoints() {
-
- searching = exit = false;
- maxPly = splitPointsSize = 0;
- activeSplitPoint = NULL;
- idx = Threads.size();
-
- 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() {
- exit = true; // Search must be already finished
- notify_one();
- thread_join(handle); // Wait for thread termination
-}
-
-
-// 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 TimerThread::idle_loop() {
-
- while (!exit)
- {
- mutex.lock();
-
- if (!exit)
- sleepCondition.wait_for(mutex, msec ? msec : INT_MAX);
+ assert(!searching);
- mutex.unlock();
-
- if (msec)
- check_time();
- }
+ exit = true;
+ start_searching();
+ stdThread.join();
}
+/// Thread::bestMoveCount(Move move) return best move counter for the given root move
-// 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 MainThread::idle_loop() {
+int Thread::best_move_count(Move move) {
- while (true)
- {
- mutex.lock();
+ auto rm = std::find(rootMoves.begin() + pvIdx,
+ rootMoves.begin() + pvLast, move);
- thinking = false;
-
- while (!thinking && !exit)
- {
- Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
- sleepCondition.wait(mutex);
- }
-
- mutex.unlock();
-
- if (exit)
- return;
-
- searching = true;
-
- Search::think();
-
- assert(searching);
-
- searching = false;
- }
+ return rm != rootMoves.begin() + pvLast ? rm->bestMoveCount : 0;
}
+/// Thread::clear() reset histories, usually before a new game
-// Thread::notify_one() wakes up the thread when there is some search to do
+void Thread::clear() {
-void Thread::notify_one() {
+ counterMoves.fill(MOVE_NONE);
+ mainHistory.fill(0);
+ captureHistory.fill(0);
- mutex.lock();
- sleepCondition.notify_one();
- mutex.unlock();
-}
+ for (bool inCheck : { false, true })
+ for (StatsType c : { NoCaptures, Captures })
+ for (auto& to : continuationHistory[inCheck][c])
+ for (auto& h : to)
+ h->fill(0);
-
-// Thread::wait_for() set the thread to sleep until condition 'b' turns true
-
-void Thread::wait_for(volatile const bool& b) {
-
- mutex.lock();
- while (!b) sleepCondition.wait(mutex);
- mutex.unlock();
-}
-
-
-// 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 = activeSplitPoint; sp; sp = sp->parentSplitPoint)
- if (sp->cutoff)
- return true;
-
- 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 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).
+void Thread::start_searching() {
-bool Thread::is_available_to(Thread* master) const {
-
- 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 size = splitPointsSize;
-
- // 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 !size || (splitPoints[size - 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 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.
+/// 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() {
- sleepWhileIdle = true;
- timer = new TimerThread();
- threads.push_back(new MainThread());
- read_uci_options();
+ std::unique_lock<std::mutex> lk(mutex);
+ cv.wait(lk, [&]{ return !searching; });
}
-// exit() cleanly terminates the threads before the program exits
-
-void ThreadPool::exit() {
-
- delete timer; // As first because check_time() accesses threads data
-
- for (size_t i = 0; i < threads.size(); i++)
- delete threads[i];
-}
+/// Thread::idle_loop() is where the thread is parked, blocked on the
+/// condition variable, when it has no work to do.
+void Thread::idle_loop() {
-// 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.
+ // 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);
-void ThreadPool::read_uci_options() {
-
- maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- size_t requested = Options["Threads"];
+ while (true)
+ {
+ std::unique_lock<std::mutex> lk(mutex);
+ searching = false;
+ cv.notify_one(); // Wake up anyone waiting for search finished
+ cv.wait(lk, [&]{ return searching; });
- assert(requested > 0);
+ if (exit)
+ return;
- while (threads.size() < requested)
- threads.push_back(new Thread());
+ lk.unlock();
- while (threads.size() > requested)
- {
- delete threads.back();
- threads.pop_back();
+ 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.
-// slave_available() tries to find an idle thread which is available as a slave
-// for the thread 'master'.
+void ThreadPool::set(size_t requested) {
-bool ThreadPool::slave_available(Thread* master) const {
+ if (size() > 0) { // destroy any existing thread(s)
+ main()->wait_for_search_finished();
- for (size_t i = 0; i < threads.size(); i++)
- if (threads[i]->is_available_to(master))
- return true;
+ while (size() > 0)
+ delete back(), pop_back();
+ }
- return false;
-}
+ if (requested > 0) { // create new thread(s)
+ push_back(new MainThread(0));
+ while (size() < requested)
+ push_back(new Thread(size()));
+ clear();
-// 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), 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 Thread::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 <= alpha && alpha < beta && beta <= VALUE_INFINITE);
- assert(bestValue > -VALUE_INFINITE);
- assert(depth >= Threads.minimumSplitDepth);
-
- assert(searching);
- assert(splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
-
- // Pick the next available split point from the split point stack
- SplitPoint& sp = splitPoints[splitPointsSize];
-
- sp.masterThread = this;
- sp.parentSplitPoint = activeSplitPoint;
- sp.slavesMask = 1ULL << idx;
- sp.depth = depth;
- sp.bestMove = *bestMove;
- sp.threatMove = threatMove;
- sp.alpha = alpha;
- sp.beta = beta;
- sp.nodeType = nodeType;
- sp.bestValue = bestValue;
- sp.movePicker = ∓
- sp.moveCount = moveCount;
- sp.pos = &pos;
- sp.nodes = 0;
- sp.cutoff = false;
- sp.ss = ss;
-
- // Try to allocate available threads and ask them to start searching setting
- // 'searching' flag. This must be done under lock protection to avoid concurrent
- // allocation of the same slave by another master.
- Threads.mutex.lock();
- sp.mutex.lock();
-
- splitPointsSize++;
- 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(this) && ++slavesCnt <= Threads.maxThreadsPerSplitPoint)
- {
- sp.slavesMask |= 1ULL << Threads[i].idx;
- Threads[i].activeSplitPoint = &sp;
- Threads[i].searching = true; // Slave leaves idle_loop()
- Threads[i].notify_one(); // Could be sleeping
- }
-
- sp.mutex.unlock();
- Threads.mutex.unlock();
-
- // Everything is set up. The master thread enters the idle loop, from which
- // 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 > 1 || Fake)
- {
- Thread::idle_loop(); // Force a call to base class idle_loop()
+ // Reallocate the hash with the new threadpool size
+ TT.resize(Options["Hash"]);
- // 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(!searching);
+ // Init thread number dependent search params.
+ Search::init();
}
+}
- // We have returned from the idle loop, which means that all threads are
- // finished. Note that setting 'searching' and decreasing splitPointsSize is
- // done under lock protection to avoid a race with Thread::is_available_to().
- Threads.mutex.lock();
- sp.mutex.lock();
+/// ThreadPool::clear() sets threadPool data to initial values.
- searching = true;
- splitPointsSize--;
- activeSplitPoint = sp.parentSplitPoint;
- pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
- *bestMove = sp.bestMove;
+void ThreadPool::clear() {
- sp.mutex.unlock();
- Threads.mutex.unlock();
+ for (Thread* th : *this)
+ th->clear();
- return sp.bestValue;
+ main()->callsCnt = 0;
+ main()->previousScore = VALUE_INFINITE;
+ main()->previousTimeReduction = 1.0;
}
-// Explicit template instantiations
-template Value Thread::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
-template Value Thread::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
+/// 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.
+void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
+ const Search::LimitsType& limits, bool ponderMode) {
-// wait_for_think_finished() waits for main thread to go to sleep then returns
+ main()->wait_for_search_finished();
-void ThreadPool::wait_for_think_finished() {
-
- MainThread* t = main_thread();
- t->mutex.lock();
- while (t->thinking) 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_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
-// so to start a new search, then returns immediately.
+ if (!rootMoves.empty())
+ Tablebases::rank_root_moves(pos, rootMoves);
-void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
- const std::vector<Move>& searchMoves, StateStackPtr& states) {
- wait_for_think_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 = Time::now(); // 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();
- RootPos = 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()
- || std::count(searchMoves.begin(), searchMoves.end(), ml.move()))
- RootMoves.push_back(RootMove(ml.move()));
+ setupStates->back() = tmp;
- main_thread()->thinking = true;
- main_thread()->notify_one(); // Starts main thread
+ main()->start_searching();
}
projects / stockfish / blobdiff