/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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
#include "search.h"
#include "thread.h"
#include "uci.h"
-
-using namespace Search;
+#include "syzygy/tbprobe.h"
+#include "tt.h"
ThreadPool Threads; // Global object
-extern void check_time();
-
-namespace {
-
- // 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().
-
- extern "C" { long start_routine(ThreadBase* 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 alredy set.
- // Helpers to launch a thread after creation and joining before delete. Must be
- // outside Thread c'tor and d'tor because the object will be fully initialized
- // when start_routine (and hence virtual idle_loop) is called and when joining.
-
- template<typename T> T* new_thread() {
- T* th = new T();
- thread_create(th->handle, start_routine, th); // Will go to sleep
- return th;
- }
-
- void delete_thread(ThreadBase* th) {
- th->exit = true; // Search must be already finished
- th->notify_one();
- thread_join(th->handle); // Wait for thread termination
- delete th;
- }
+Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
+ wait_for_search_finished();
}
-// notify_one() wakes up the thread when there is some work to do
-
-void ThreadBase::notify_one() {
-
- mutex.lock();
- sleepCondition.notify_one();
- mutex.unlock();
-}
-
+/// Thread destructor wakes up the thread in idle_loop() and waits
+/// for its termination. Thread should be already waiting.
-// wait_for() set the thread to sleep until condition 'b' turns true
+Thread::~Thread() {
-void ThreadBase::wait_for(volatile const bool& b) {
+ assert(!searching);
- mutex.lock();
- while (!b) sleepCondition.wait(mutex);
- mutex.unlock();
+ exit = true;
+ start_searching();
+ stdThread.join();
}
-// Thread c'tor just inits data and does not launch any execution thread.
-// Such a thread will only be started when c'tor returns.
-
-Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
-
- searching = false;
- maxPly = splitPointsSize = 0;
- activeSplitPoint = NULL;
- activePosition = NULL;
- idx = Threads.size(); // Starts from 0
-}
+/// Thread::clear() reset histories, usually before a new game
+void Thread::clear() {
-// cutoff_occurred() checks whether a beta cutoff has occurred in the
-// current active split point, or in some ancestor of the split point.
+ counterMoves.fill(MOVE_NONE);
+ mainHistory.fill(0);
+ captureHistory.fill(0);
-bool Thread::cutoff_occurred() const {
+ for (auto& to : contHistory)
+ for (auto& h : to)
+ h.get()->fill(0);
- for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parentSplitPoint)
- if (sp->cutoff)
- return true;
-
- return false;
+ contHistory[NO_PIECE][0].get()->fill(Search::CounterMovePruneThreshold - 1);
}
+/// Thread::start_searching() wakes up the thread that will start the search
-// Thread::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 slave's split point
-// stack (the "helpful master concept" in YBWC terminology).
-
-bool Thread::available_to(const Thread* master) const {
+void Thread::start_searching() {
- if (searching)
- return false;
-
- // Make a local copy to be sure it doesn't become zero under our feet while
- // testing next condition and so leading to an out of bounds access.
- const 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.test(master->idx);
+ std::lock_guard<Mutex> lk(mutex);
+ searching = true;
+ cv.notify_one(); // Wake up the thread in idle_loop()
}
-// TimerThread::idle_loop() is where the timer thread waits msec milliseconds
-// and then calls check_time(). If msec is 0 thread sleeps until it's woken up.
-
-void TimerThread::idle_loop() {
+/// Thread::wait_for_search_finished() blocks on the condition variable
+/// until the thread has finished searching.
- while (!exit)
- {
- mutex.lock();
-
- if (!exit)
- sleepCondition.wait_for(mutex, run ? Resolution : INT_MAX);
+void Thread::wait_for_search_finished() {
- mutex.unlock();
-
- if (run)
- check_time();
- }
+ std::unique_lock<Mutex> lk(mutex);
+ cv.wait(lk, [&]{ return !searching; });
}
-// MainThread::idle_loop() is where the main thread is parked waiting to be started
-// when there is a new search. The main thread will launch all the slave threads.
+/// Thread::idle_loop() is where the thread is parked, blocked on the
+/// condition variable, when it has no work to do.
-void MainThread::idle_loop() {
+void Thread::idle_loop() {
+
+ // 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 (true)
{
- mutex.lock();
-
- thinking = false;
-
- while (!thinking && !exit)
- {
- Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed
- sleepCondition.wait(mutex);
- }
-
- mutex.unlock();
+ std::unique_lock<Mutex> lk(mutex);
+ searching = false;
+ cv.notify_one(); // Wake up anyone waiting for search finished
+ cv.wait(lk, [&]{ return searching; });
if (exit)
return;
- searching = true;
-
- Search::think();
-
- assert(searching);
+ lk.unlock();
- searching = false;
+ search();
}
}
+/// ThreadPool::set() creates/destroys threads to match the requested number.
+/// Created and launched threads will go immediately to sleep in idle_loop.
+/// Upon resizing, threads are recreated to allow for binding if necessary.
-// init() is called at startup to create and launch requested threads, that will
-// go immediately to sleep. We cannot use a c'tor because Threads is a static
-// object and we need a fully initialized engine at this point due to allocation
-// of Endgames in Thread c'tor.
-
-void ThreadPool::init() {
-
- timer = new_thread<TimerThread>();
- push_back(new_thread<MainThread>());
- read_uci_options();
-}
-
-
-// exit() cleanly terminates the threads before the program exits. Cannot be done in
-// d'tor because we have to terminate the threads before to free ThreadPool object.
-
-void ThreadPool::exit() {
-
- delete_thread(timer); // As first because check_time() accesses threads data
-
- for (iterator it = begin(); it != end(); ++it)
- delete_thread(*it);
-}
-
-
-// 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 all possible threads
-// in advance (which include pawns and material tables), even if only a few
-// are to be used.
-
-void ThreadPool::read_uci_options() {
-
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- size_t requested = Options["Threads"];
-
- assert(requested > 0);
-
- // If zero (default) then set best minimum split depth automatically
- if (!minimumSplitDepth)
- minimumSplitDepth = requested < 8 ? 4 * ONE_PLY : 7 * ONE_PLY;
+void ThreadPool::set(size_t requested) {
- while (size() < requested)
- push_back(new_thread<Thread>());
+ if (size() > 0) { // destroy any existing thread(s)
+ main()->wait_for_search_finished();
- while (size() > requested)
- {
- delete_thread(back());
- pop_back();
+ while (size() > 0)
+ delete back(), pop_back();
}
-}
-
-
-// available_slave() tries to find an idle thread which is available as a slave
-// for the thread 'master'.
-
-Thread* ThreadPool::available_slave(const Thread* master) const {
-
- for (const_iterator it = begin(); it != end(); ++it)
- if ((*it)->available_to(master))
- return *it;
-
- return NULL;
-}
+ if (requested > 0) { // create new thread(s)
+ push_back(new MainThread(0));
-// 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.
-
-void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bestValue,
- Move* bestMove, Depth depth, int moveCount,
- MovePicker* movePicker, int nodeType, bool cutNode) {
-
- assert(pos.pos_is_ok());
- assert(-VALUE_INFINITE < *bestValue && *bestValue <= alpha && alpha < beta && beta <= 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 = 0, sp.slavesMask.set(idx);
- sp.depth = depth;
- sp.bestValue = *bestValue;
- sp.bestMove = *bestMove;
- sp.alpha = alpha;
- sp.beta = beta;
- sp.nodeType = nodeType;
- sp.cutNode = cutNode;
- sp.movePicker = 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();
-
- sp.allSlavesSearching = true; // Must be set under lock protection
- ++splitPointsSize;
- activeSplitPoint = &sp;
- activePosition = NULL;
-
- for (Thread* slave; (slave = Threads.available_slave(this)) != NULL; )
- {
- sp.slavesMask.set(slave->idx);
- slave->activeSplitPoint = &sp;
- slave->searching = true; // Slave leaves idle_loop()
- slave->notify_one(); // Could be sleeping
+ while (size() < requested)
+ push_back(new Thread(size()));
+ clear();
}
- // 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.
- sp.mutex.unlock();
- Threads.mutex.unlock();
+ // Reallocate the hash with the new threadpool size
+ TT.resize(Options["Hash"]);
+}
- Thread::idle_loop(); // Force a call to base class idle_loop()
+/// ThreadPool::clear() sets threadPool data to initial values.
- // In the helpful master concept, a master can help only a sub-tree of its
- // split point and because everything is finished here, it's not possible
- // for the master to be booked.
- assert(!searching);
- assert(!activePosition);
+void ThreadPool::clear() {
- // 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::available_to().
- Threads.mutex.lock();
- sp.mutex.lock();
+ for (Thread* th : *this)
+ th->clear();
- searching = true;
- --splitPointsSize;
- activeSplitPoint = sp.parentSplitPoint;
- activePosition = &pos;
- pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
- *bestMove = sp.bestMove;
- *bestValue = sp.bestValue;
-
- sp.mutex.unlock();
- Threads.mutex.unlock();
+ main()->callsCnt = 0;
+ main()->previousScore = VALUE_INFINITE;
+ main()->previousTimeReduction = 1.0;
}
-// wait_for_think_finished() waits for main thread to go to sleep then returns
+/// 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::wait_for_think_finished() {
+void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
+ const Search::LimitsType& limits, bool ponderMode) {
- MainThread* t = main();
- t->mutex.lock();
- while (t->thinking) sleepCondition.wait(t->mutex);
- t->mutex.unlock();
-}
+ main()->wait_for_search_finished();
+ stopOnPonderhit = stop = false;
+ ponder = ponderMode;
+ Search::Limits = limits;
+ Search::RootMoves rootMoves;
-// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
-// so to start a new search, then returns immediately.
+ for (const auto& m : MoveList<LEGAL>(pos))
+ if ( limits.searchmoves.empty()
+ || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+ rootMoves.emplace_back(m);
-void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, StateStackPtr& states) {
+ if (!rootMoves.empty())
+ Tablebases::rank_root_moves(pos, rootMoves);
- 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();
- RootMoves.clear();
- RootPos = pos;
- Limits = limits;
- if (states.get()) // If we don't set a new position, preserve current state
+ for (Thread* th : *this)
{
- SetupStates = states; // Ownership transfer here
- assert(!states.get());
+ th->nodes = th->tbHits = th->nmpMinPly = 0;
+ th->rootDepth = th->completedDepth = DEPTH_ZERO;
+ th->rootMoves = rootMoves;
+ th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
}
- for (MoveList<LEGAL> it(pos); *it; ++it)
- if ( limits.searchmoves.empty()
- || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), *it))
- RootMoves.push_back(RootMove(*it));
+ setupStates->back() = tmp;
- main()->thinking = true;
- main()->notify_one(); // Starts main thread
+ main()->start_searching();
}
projects / stockfish / blobdiff