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59f1d0c7dd
Fixes issues #2126 and #2189 where no progress in rootDepth is made for particular fens: 8/8/3P3k/8/1p6/8/1P6/1K3n2 b - - 0 1 8/1r1rp1k1/1b1pPp2/2pP1Pp1/1pP3Pp/pP5P/P5K1/8 w - - 79 46 the cause are the shuffle extensions. Upon closer analysis, it appears that in these cases a shuffle extension is made for every node searched, and progess can not be made. This patch implements a fix, namely to limit the number of extensions relative to the number of nodes searched. The ratio employed is 1/4, which fixes the issues seen so far, but it is a heuristic, and I expect that certain positions might require an even smaller fraction. The patch was tested as a bug fix and passed: STC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 56601 W: 12633 L: 12581 D: 31387 http://tests.stockfishchess.org/tests/view/5d02b37a0ebc5925cf09f6da LTC: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 52042 W: 8907 L: 8837 D: 34298 http://tests.stockfishchess.org/tests/view/5d0319420ebc5925cf09fe57 Furthermore, to confirm that the shuffle extension in this form indeed still brings Elo, one more test at VLTC was performed: VLTC: LLR: 2.96 (-2.94,2.94) [0.00,3.50] Total: 142022 W: 20963 L: 20435 D: 100624 http://tests.stockfishchess.org/tests/view/5d03630d0ebc5925cf0a011a Bench: 3961247
126 lines
3.4 KiB
C++
126 lines
3.4 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
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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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#ifndef THREAD_H_INCLUDED
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#define THREAD_H_INCLUDED
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#include <atomic>
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#include <condition_variable>
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#include <mutex>
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#include <thread>
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#include <vector>
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#include "material.h"
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#include "movepick.h"
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#include "pawns.h"
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#include "position.h"
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#include "search.h"
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#include "thread_win32_osx.h"
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/// Thread class keeps together all the thread-related stuff. We use
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/// per-thread pawn and material hash tables so that once we get a
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/// pointer to an entry its life time is unlimited and we don't have
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/// to care about someone changing the entry under our feet.
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class Thread {
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Mutex mutex;
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ConditionVariable cv;
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size_t idx;
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bool exit = false, searching = true; // Set before starting std::thread
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NativeThread stdThread;
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public:
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explicit Thread(size_t);
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virtual ~Thread();
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virtual void search();
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void clear();
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void idle_loop();
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void start_searching();
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void wait_for_search_finished();
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Pawns::Table pawnsTable;
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Material::Table materialTable;
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size_t pvIdx, pvLast, shuffleExts;
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int selDepth, nmpMinPly;
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Color nmpColor;
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std::atomic<uint64_t> nodes, tbHits, bestMoveChanges;
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Position rootPos;
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Search::RootMoves rootMoves;
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Depth rootDepth, completedDepth;
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CounterMoveHistory counterMoves;
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ButterflyHistory mainHistory;
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CapturePieceToHistory captureHistory;
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ContinuationHistory continuationHistory;
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Score contempt;
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};
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/// MainThread is a derived class specific for main thread
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struct MainThread : public Thread {
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using Thread::Thread;
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void search() override;
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void check_time();
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double previousTimeReduction;
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Value previousScore;
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int callsCnt;
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bool stopOnPonderhit;
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std::atomic_bool ponder;
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};
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/// ThreadPool struct handles all the threads-related stuff like init, starting,
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/// parking and, most importantly, launching a thread. All the access to threads
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/// is done through this class.
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struct ThreadPool : public std::vector<Thread*> {
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void start_thinking(Position&, StateListPtr&, const Search::LimitsType&, bool = false);
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void clear();
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void set(size_t);
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MainThread* main() const { return static_cast<MainThread*>(front()); }
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uint64_t nodes_searched() const { return accumulate(&Thread::nodes); }
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uint64_t tb_hits() const { return accumulate(&Thread::tbHits); }
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std::atomic_bool stop;
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private:
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StateListPtr setupStates;
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uint64_t accumulate(std::atomic<uint64_t> Thread::* member) const {
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uint64_t sum = 0;
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for (Thread* th : *this)
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sum += (th->*member).load(std::memory_order_relaxed);
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return sum;
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}
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};
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extern ThreadPool Threads;
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#endif // #ifndef THREAD_H_INCLUDED
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