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https://github.com/sockspls/badfish
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Follow up cleanup of #4968, removes the global variables from search and instead uses a dedicated tb config struct. closes https://github.com/official-stockfish/Stockfish/pull/4982 No functional change
272 lines
9.1 KiB
C++
272 lines
9.1 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2024 The Stockfish developers (see AUTHORS file)
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "thread.h"
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#include <algorithm>
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#include <cassert>
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#include <cmath>
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#include <cstdlib>
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#include <deque>
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#include <memory>
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#include <unordered_map>
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#include <utility>
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#include "misc.h"
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#include "movegen.h"
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#include "search.h"
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#include "syzygy/tbprobe.h"
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#include "timeman.h"
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#include "tt.h"
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#include "types.h"
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#include "ucioption.h"
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namespace Stockfish {
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// Constructor launches the thread and waits until it goes to sleep
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// in idle_loop(). Note that 'searching' and 'exit' should be already set.
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Thread::Thread(Search::SharedState& sharedState,
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std::unique_ptr<Search::ISearchManager> sm,
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size_t n) :
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worker(std::make_unique<Search::Worker>(sharedState, std::move(sm), n)),
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idx(n),
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nthreads(sharedState.options["Threads"]),
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stdThread(&Thread::idle_loop, this) {
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wait_for_search_finished();
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}
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// Destructor wakes up the thread in idle_loop() and waits
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// for its termination. Thread should be already waiting.
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Thread::~Thread() {
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assert(!searching);
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exit = true;
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start_searching();
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stdThread.join();
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}
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// Wakes up the thread that will start the search
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void Thread::start_searching() {
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mutex.lock();
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searching = true;
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mutex.unlock(); // Unlock before notifying saves a few CPU-cycles
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cv.notify_one(); // Wake up the thread in idle_loop()
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}
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// Blocks on the condition variable
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// until the thread has finished searching.
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void Thread::wait_for_search_finished() {
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std::unique_lock<std::mutex> lk(mutex);
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cv.wait(lk, [&] { return !searching; });
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}
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// Thread gets parked here, blocked on the
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// condition variable, when it has no work to do.
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void Thread::idle_loop() {
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// If OS already scheduled us on a different group than 0 then don't overwrite
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// the choice, eventually we are one of many one-threaded processes running on
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// some Windows NUMA hardware, for instance in fishtest. To make it simple,
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// just check if running threads are below a threshold, in this case, all this
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// NUMA machinery is not needed.
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if (nthreads > 8)
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WinProcGroup::bindThisThread(idx);
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while (true)
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{
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std::unique_lock<std::mutex> lk(mutex);
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searching = false;
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cv.notify_one(); // Wake up anyone waiting for search finished
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cv.wait(lk, [&] { return searching; });
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if (exit)
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return;
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lk.unlock();
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worker->start_searching();
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}
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}
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// Creates/destroys threads to match the requested number.
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// Created and launched threads will immediately go to sleep in idle_loop.
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// Upon resizing, threads are recreated to allow for binding if necessary.
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void ThreadPool::set(Search::SharedState sharedState) {
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if (threads.size() > 0) // destroy any existing thread(s)
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{
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main_thread()->wait_for_search_finished();
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while (threads.size() > 0)
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delete threads.back(), threads.pop_back();
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}
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const size_t requested = sharedState.options["Threads"];
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if (requested > 0) // create new thread(s)
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{
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threads.push_back(new Thread(
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sharedState, std::unique_ptr<Search::ISearchManager>(new Search::SearchManager()), 0));
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while (threads.size() < requested)
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threads.push_back(new Thread(
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sharedState, std::unique_ptr<Search::ISearchManager>(new Search::NullSearchManager()),
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threads.size()));
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clear();
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main_thread()->wait_for_search_finished();
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// Reallocate the hash with the new threadpool size
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sharedState.tt.resize(sharedState.options["Hash"], requested);
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}
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}
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// Sets threadPool data to initial values
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void ThreadPool::clear() {
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for (Thread* th : threads)
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th->worker->clear();
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main_manager()->callsCnt = 0;
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main_manager()->bestPreviousScore = VALUE_INFINITE;
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main_manager()->bestPreviousAverageScore = VALUE_INFINITE;
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main_manager()->previousTimeReduction = 1.0;
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main_manager()->tm.clear();
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}
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// Wakes up main thread waiting in idle_loop() and
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// returns immediately. Main thread will wake up other threads and start the search.
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void ThreadPool::start_thinking(const OptionsMap& options,
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Position& pos,
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StateListPtr& states,
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Search::LimitsType limits,
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bool ponderMode) {
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main_thread()->wait_for_search_finished();
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main_manager()->stopOnPonderhit = stop = false;
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main_manager()->ponder = ponderMode;
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increaseDepth = true;
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Search::RootMoves rootMoves;
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for (const auto& m : MoveList<LEGAL>(pos))
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if (limits.searchmoves.empty()
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|| std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
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rootMoves.emplace_back(m);
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Tablebases::Config tbConfig = Tablebases::rank_root_moves(options, pos, rootMoves);
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// After ownership transfer 'states' becomes empty, so if we stop the search
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// and call 'go' again without setting a new position states.get() == nullptr.
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assert(states.get() || setupStates.get());
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if (states.get())
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setupStates = std::move(states); // Ownership transfer, states is now empty
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// We use Position::set() to set root position across threads. But there are
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// some StateInfo fields (previous, pliesFromNull, capturedPiece) that cannot
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// be deduced from a fen string, so set() clears them and they are set from
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// setupStates->back() later. The rootState is per thread, earlier states are shared
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// since they are read-only.
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for (Thread* th : threads)
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{
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th->worker->limits = limits;
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th->worker->nodes = th->worker->tbHits = th->worker->nmpMinPly =
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th->worker->bestMoveChanges = 0;
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th->worker->rootDepth = th->worker->completedDepth = 0;
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th->worker->rootMoves = rootMoves;
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th->worker->rootPos.set(pos.fen(), pos.is_chess960(), &th->worker->rootState);
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th->worker->rootState = setupStates->back();
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th->worker->tbConfig = tbConfig;
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}
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main_thread()->start_searching();
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}
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Thread* ThreadPool::get_best_thread() const {
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Thread* bestThread = threads.front();
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std::unordered_map<Move, int64_t, Move::MoveHash> votes;
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Value minScore = VALUE_NONE;
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// Find the minimum score of all threads
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for (Thread* th : threads)
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minScore = std::min(minScore, th->worker->rootMoves[0].score);
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// Vote according to score and depth, and select the best thread
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auto thread_value = [minScore](Thread* th) {
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return (th->worker->rootMoves[0].score - minScore + 14) * int(th->worker->completedDepth);
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};
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for (Thread* th : threads)
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votes[th->worker->rootMoves[0].pv[0]] += thread_value(th);
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for (Thread* th : threads)
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if (std::abs(bestThread->worker->rootMoves[0].score) >= VALUE_TB_WIN_IN_MAX_PLY)
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{
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// Make sure we pick the shortest mate / TB conversion or stave off mate the longest
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if (th->worker->rootMoves[0].score > bestThread->worker->rootMoves[0].score)
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bestThread = th;
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}
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else if (th->worker->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY
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|| (th->worker->rootMoves[0].score > VALUE_TB_LOSS_IN_MAX_PLY
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&& (votes[th->worker->rootMoves[0].pv[0]]
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> votes[bestThread->worker->rootMoves[0].pv[0]]
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|| (votes[th->worker->rootMoves[0].pv[0]]
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== votes[bestThread->worker->rootMoves[0].pv[0]]
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&& thread_value(th) * int(th->worker->rootMoves[0].pv.size() > 2)
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> thread_value(bestThread)
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* int(bestThread->worker->rootMoves[0].pv.size() > 2)))))
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bestThread = th;
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return bestThread;
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}
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// Start non-main threads
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// Will be invoked by main thread after it has started searching
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void ThreadPool::start_searching() {
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for (Thread* th : threads)
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if (th != threads.front())
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th->start_searching();
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}
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// Wait for non-main threads
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void ThreadPool::wait_for_search_finished() const {
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for (Thread* th : threads)
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if (th != threads.front())
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th->wait_for_search_finished();
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}
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} // namespace Stockfish
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