From 4b71d8e20293bdc5db5dbb07ae75f3ef65497642 Mon Sep 17 00:00:00 2001 From: Robert Nurnberg Date: Fri, 14 Nov 2025 10:07:14 +0100 Subject: [PATCH] Allow time checking after each DTZ probe This PR allows for time checking within Tablebases::rank_root_moves(). The principal application for now is syzygy_extend_pv(). In the past, Stockfish suffered some time losses at e.g. TCEC when the HDD with the DTZ tables was too slow for the chosen move overhead setting, see #5894. ``` > ./fastchess -engine name="patch" cmd=./stockfish.patch -engine name="master" cmd=./stockfish.master -each tc=10+0.1 option.SyzygyPath=/disk1/syzygy/3-4-5-6/WDL:/disk2/syzygy/3-4-5-6/DTZ -draw movenumber=34 movecount=8 score=20 -openings file=UHO_Lichess_4852_v1.epd format=epd -rounds 50 -repeat -concurrency 16 ... Results of patch vs master (10+0.1, 1t, 16MB, UHO_Lichess_4852_v1.epd): Elo: 59.64 +/- 35.35, nElo: 117.61 +/- 68.10 LOS: 99.96 %, DrawRatio: 56.00 %, PairsRatio: 4.50 Games: 100, Wins: 34, Losses: 17, Draws: 49, Points: 58.5 (58.50 %) Ptnml(0-2): [0, 4, 28, 15, 3], WL/DD Ratio: 0.87 -------------------------------------------------- Player: master Timeouts: 19 Crashed: 0 Finished match ``` closes https://github.com/official-stockfish/Stockfish/pull/6422 No functional change --- src/search.cpp | 12 +++++++----- src/syzygy/tbprobe.cpp | 27 +++++++++++++++------------ src/syzygy/tbprobe.h | 17 ++++++++++++----- 3 files changed, 34 insertions(+), 22 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index e4ef2d42e..9fb7b702f 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -857,8 +857,8 @@ Value Search::Worker::search( auto futility_margin = [&](Depth d) { Value futilityMult = 91 - 21 * !ss->ttHit; - return futilityMult * d // - - 2094 * improving * futilityMult / 1024 // + return futilityMult * d // + - 2094 * improving * futilityMult / 1024 // - 331 * opponentWorsening * futilityMult / 1024 // + std::abs(correctionValue) / 158105; }; @@ -1980,8 +1980,9 @@ void syzygy_extend_pv(const OptionsMap& options, for (const auto& m : MoveList(pos)) legalMoves.emplace_back(m); - Tablebases::Config config = Tablebases::rank_root_moves(options, pos, legalMoves); - RootMove& rm = *std::find(legalMoves.begin(), legalMoves.end(), pvMove); + Tablebases::Config config = + Tablebases::rank_root_moves(options, pos, legalMoves, false, time_abort); + RootMove& rm = *std::find(legalMoves.begin(), legalMoves.end(), pvMove); if (legalMoves[0].tbRank != rm.tbRank) break; @@ -2040,7 +2041,8 @@ void syzygy_extend_pv(const OptionsMap& options, [](const Search::RootMove& a, const Search::RootMove& b) { return a.tbRank > b.tbRank; }); // The winning side tries to minimize DTZ, the losing side maximizes it - Tablebases::Config config = Tablebases::rank_root_moves(options, pos, legalMoves, true); + Tablebases::Config config = + Tablebases::rank_root_moves(options, pos, legalMoves, true, time_abort); // If DTZ is not available we might not find a mate, so we bail out if (!config.rootInTB || config.cardinality > 0) diff --git a/src/syzygy/tbprobe.cpp b/src/syzygy/tbprobe.cpp index 657866ba4..c8ff60739 100644 --- a/src/syzygy/tbprobe.cpp +++ b/src/syzygy/tbprobe.cpp @@ -1594,10 +1594,11 @@ int Tablebases::probe_dtz(Position& pos, ProbeState* result) { // Use the DTZ tables to rank root moves. // // A return value false indicates that not all probes were successful. -bool Tablebases::root_probe(Position& pos, - Search::RootMoves& rootMoves, - bool rule50, - bool rankDTZ) { +bool Tablebases::root_probe(Position& pos, + Search::RootMoves& rootMoves, + bool rule50, + bool rankDTZ, + const std::function& time_abort) { ProbeState result = OK; StateInfo st; @@ -1642,7 +1643,7 @@ bool Tablebases::root_probe(Position& pos, pos.undo_move(m.pv[0]); - if (result == FAIL) + if (time_abort() || result == FAIL) return false; // Better moves are ranked higher. Certain wins are ranked equally. @@ -1707,10 +1708,11 @@ bool Tablebases::root_probe_wdl(Position& pos, Search::RootMoves& rootMoves, boo return true; } -Config Tablebases::rank_root_moves(const OptionsMap& options, - Position& pos, - Search::RootMoves& rootMoves, - bool rankDTZ) { +Config Tablebases::rank_root_moves(const OptionsMap& options, + Position& pos, + Search::RootMoves& rootMoves, + bool rankDTZ, + const std::function& time_abort) { Config config; if (rootMoves.empty()) @@ -1733,10 +1735,11 @@ Config Tablebases::rank_root_moves(const OptionsMap& options, if (config.cardinality >= popcount(pos.pieces()) && !pos.can_castle(ANY_CASTLING)) { - // Rank moves using DTZ tables - config.rootInTB = root_probe(pos, rootMoves, options["Syzygy50MoveRule"], rankDTZ); + // Rank moves using DTZ tables, bail out if time_abort flags zeitnot + config.rootInTB = + root_probe(pos, rootMoves, options["Syzygy50MoveRule"], rankDTZ, time_abort); - if (!config.rootInTB) + if (!config.rootInTB && !time_abort()) { // DTZ tables are missing; try to rank moves using WDL tables dtz_available = false; diff --git a/src/syzygy/tbprobe.h b/src/syzygy/tbprobe.h index c34338fe3..4a6c3b763 100644 --- a/src/syzygy/tbprobe.h +++ b/src/syzygy/tbprobe.h @@ -19,6 +19,7 @@ #ifndef TBPROBE_H #define TBPROBE_H +#include #include #include @@ -66,12 +67,18 @@ extern int MaxCardinality; void init(const std::string& paths); WDLScore probe_wdl(Position& pos, ProbeState* result); int probe_dtz(Position& pos, ProbeState* result); -bool root_probe(Position& pos, Search::RootMoves& rootMoves, bool rule50, bool rankDTZ); +bool root_probe(Position& pos, + Search::RootMoves& rootMoves, + bool rule50, + bool rankDTZ, + const std::function& time_abort); bool root_probe_wdl(Position& pos, Search::RootMoves& rootMoves, bool rule50); -Config rank_root_moves(const OptionsMap& options, - Position& pos, - Search::RootMoves& rootMoves, - bool rankDTZ = false); +Config rank_root_moves( + const OptionsMap& options, + Position& pos, + Search::RootMoves& rootMoves, + bool rankDTZ = false, + const std::function& time_abort = []() { return false; }); } // namespace Stockfish::Tablebases