Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2018 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
ThreadPool Threads; // Global object
-/// Thread constructor launches the thread and then waits until it goes to sleep
-/// in idle_loop().
-Thread::Thread() {
+/// Thread constructor launches the thread and waits until it goes to sleep
+/// in idle_loop(). Note that 'searching' and 'exit' should be alredy set.
- exit = false;
- maxPly = 0;
- nodes = tbHits = 0;
- idx = Threads.size(); // Start from 0
+Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
- std::unique_lock<Mutex> lk(mutex);
- searching = true;
- nativeThread = std::thread(&Thread::idle_loop, this);
- sleepCondition.wait(lk, [&]{ return !searching; });
+ wait_for_search_finished();
}
-/// Thread destructor waits for thread termination before returning
+/// Thread destructor wakes up the thread in idle_loop() and waits
+/// for its termination. Thread should be already waiting.
Thread::~Thread() {
- mutex.lock();
+ assert(!searching);
+
exit = true;
- sleepCondition.notify_one();
- mutex.unlock();
- nativeThread.join();
+ start_searching();
+ stdThread.join();
}
-/// Thread::wait_for_search_finished() waits on sleep condition
-/// until not searching
+/// Thread::clear() reset histories, usually before a new game
-void Thread::wait_for_search_finished() {
+void Thread::clear() {
- std::unique_lock<Mutex> lk(mutex);
- sleepCondition.wait(lk, [&]{ return !searching; });
-}
+ counterMoves.fill(MOVE_NONE);
+ mainHistory.fill(0);
+ captureHistory.fill(0);
+ for (auto& to : contHistory)
+ for (auto& h : to)
+ h.get()->fill(0);
-/// Thread::wait() waits on sleep condition until condition is true
+ contHistory[NO_PIECE][0].get()->fill(Search::CounterMovePruneThreshold - 1);
+}
-void Thread::wait(std::atomic_bool& condition) {
+/// Thread::start_searching() wakes up the thread that will start the search
- std::unique_lock<Mutex> lk(mutex);
- sleepCondition.wait(lk, [&]{ return bool(condition); });
+void Thread::start_searching() {
+
+ std::lock_guard<Mutex> lk(mutex);
+ searching = true;
+ cv.notify_one(); // Wake up the thread in idle_loop()
}
-/// Thread::start_searching() wakes up the thread that will start the search
+/// Thread::wait_for_search_finished() blocks on the condition variable
+/// until the thread has finished searching.
-void Thread::start_searching(bool resume) {
+void Thread::wait_for_search_finished() {
std::unique_lock<Mutex> lk(mutex);
-
- if (!resume)
- searching = true;
-
- sleepCondition.notify_one();
+ cv.wait(lk, [&]{ return !searching; });
}
-/// Thread::idle_loop() is where the thread is parked when it has no work to do
+/// 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() {
- WinProcGroup::bindThisThread(idx);
+ // 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);
- while (!exit)
+ while (true)
{
std::unique_lock<Mutex> lk(mutex);
-
searching = false;
+ cv.notify_one(); // Wake up anyone waiting for search finished
+ cv.wait(lk, [&]{ return searching; });
- while (!searching && !exit)
- {
- sleepCondition.notify_one(); // Wake up any waiting thread
- sleepCondition.wait(lk);
- }
+ if (exit)
+ return;
lk.unlock();
- if (!exit)
- search();
+ search();
}
}
+/// ThreadPool::set() creates/destroys threads to match the requested number.
+/// Created and launced threads wil go immediately to sleep in idle_loop.
+/// Upon resizing, threads are recreated to allow for binding if necessary.
-/// ThreadPool::init() creates and launches requested threads that will go
-/// immediately to sleep. We cannot use a constructor because Threads is a
-/// static object and we need a fully initialized engine at this point due to
-/// allocation of Endgames in the Thread constructor.
-
-void ThreadPool::init() {
-
- push_back(new MainThread());
- read_uci_options();
-}
+void ThreadPool::set(size_t requested) {
+ if (size() > 0) { // destroy any existing thread(s)
+ main()->wait_for_search_finished();
-/// ThreadPool::exit() terminates threads before the program exits. Cannot be
-/// done in destructor because threads must be terminated before deleting any
-/// static objects while still in main().
-
-void ThreadPool::exit() {
-
- while (size())
- delete back(), pop_back();
-}
-
-
-/// ThreadPool::read_uci_options() updates internal threads parameters from the
-/// corresponding UCI options and creates/destroys threads to match requested
-/// number. Thread objects are dynamically allocated.
-
-void ThreadPool::read_uci_options() {
-
- size_t requested = Options["Threads"];
-
- assert(requested > 0);
+ while (size() > 0)
+ delete back(), pop_back();
+ }
- while (size() < requested)
- push_back(new Thread());
+ if (requested > 0) { // create new thread(s)
+ push_back(new MainThread(0));
- while (size() > requested)
- delete back(), pop_back();
+ while (size() < requested)
+ push_back(new Thread(size()));
+ clear();
+ }
}
+/// ThreadPool::clear() sets threadPool data to initial values.
-/// ThreadPool::nodes_searched() returns the number of nodes searched
-
-uint64_t ThreadPool::nodes_searched() const {
+void ThreadPool::clear() {
- uint64_t nodes = 0;
for (Thread* th : *this)
- nodes += th->nodes.load(std::memory_order_relaxed);
- return nodes;
-}
-
-
-/// ThreadPool::tb_hits() returns the number of TB hits
+ th->clear();
-uint64_t ThreadPool::tb_hits() const {
-
- uint64_t hits = 0;
- for (Thread* th : *this)
- hits += th->tbHits.load(std::memory_order_relaxed);
- return hits;
+ main()->callsCnt = 0;
+ main()->previousScore = VALUE_INFINITE;
+ main()->previousTimeReduction = 1.0;
}
-
-/// ThreadPool::start_thinking() wakes up the main thread sleeping in idle_loop()
-/// and starts a new search, then returns immediately.
+/// 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) {
+ const Search::LimitsType& limits, bool ponderMode) {
main()->wait_for_search_finished();
stopOnPonderhit = stop = false;
+ 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.push_back(Search::RootMove(m));
+ rootMoves.emplace_back(m);
if (!rootMoves.empty())
Tablebases::filter_root_moves(pos, rootMoves);
if (states.get())
setupStates = std::move(states); // Ownership transfer, states is now empty
+ // 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();
- for (Thread* th : Threads)
+ for (Thread* th : *this)
{
- th->maxPly = 0;
- th->nodes = 0;
- th->tbHits = 0;
- th->rootDepth = DEPTH_ZERO;
+ th->nodes = th->tbHits = th->nmp_ply = th->nmp_odd = 0;
+ th->rootDepth = th->completedDepth = DEPTH_ZERO;
th->rootMoves = rootMoves;
th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
}
- setupStates->back() = tmp; // Restore st->previous, cleared by Position::set()
+ setupStates->back() = tmp;
main()->start_searching();
}
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