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Code Issues Releases Wiki Activity

Refactor get_best_thread

Browse source 
Make get_best_thread function easier to understand.

Passed non-reg SMP STC:
https://tests.stockfishchess.org/tests/view/65a91c6679aa8af82b975500
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 186000 W: 46379 L: 46325 D: 93296
Ptnml(0-2): 269, 21374, 49634, 21480, 243

closes https://github.com/official-stockfish/Stockfish/pull/5001

No functional change
This commit is contained in:
Shahin M. Shahin 2024-01-18 07:31:59 +03:00 • committed by Disservin
parent e860f620aa
commit ad9fcbc496
1 changed files with 38 additions and 21 deletions
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57
src/thread.cpp
View file

@ -210,8 +210,9 @@ void ThreadPool::start_thinking(const OptionsMap& options,
Thread* ThreadPool::get_best_thread() const {
Thread* bestThread = threads.front();
std::unordered_map<Move, int64_t, Move::MoveHash> votes;
Thread* bestThread = threads.front();
Value minScore = VALUE_NONE;
// Find the minimum score of all threads
@ -219,40 +220,56 @@ Thread* ThreadPool::get_best_thread() const {
minScore = std::min(minScore, th->worker->rootMoves[0].score);
// Vote according to score and depth, and select the best thread
auto thread_value = [minScore](Thread* th) {
auto thread_voting_value = [minScore](Thread* th) {
return (th->worker->rootMoves[0].score - minScore + 14) * int(th->worker->completedDepth);
};
for (Thread* th : threads)
votes[th->worker->rootMoves[0].pv[0]] += thread_value(th);
votes[th->worker->rootMoves[0].pv[0]] += thread_voting_value(th);
for (Thread* th : threads)
if (bestThread->worker->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY)
{
const auto bestThreadScore = bestThread->worker->rootMoves[0].score;
const auto newThreadScore = th->worker->rootMoves[0].score;
const auto bestThreadPV = bestThread->worker->rootMoves[0].pv;
const auto newThreadPV = th->worker->rootMoves[0].pv;
const auto bestThreadMoveVote = votes[bestThreadPV[0]];
const auto newThreadMoveVote = votes[newThreadPV[0]];
const bool bestThreadInProvenWin = bestThreadScore >= VALUE_TB_WIN_IN_MAX_PLY;
const bool newThreadInProvenWin = newThreadScore >= VALUE_TB_WIN_IN_MAX_PLY;
const bool bestThreadInProvenLoss =
bestThreadScore != -VALUE_INFINITE && bestThreadScore <= VALUE_TB_LOSS_IN_MAX_PLY;
const bool newThreadInProvenLoss =
newThreadScore != -VALUE_INFINITE && newThreadScore <= VALUE_TB_LOSS_IN_MAX_PLY;
// Note that we make sure not to pick a thread with truncated-PV for better viewer experience.
const bool betterVotingValue =
thread_voting_value(th) * int(newThreadPV.size() > 2)
> thread_voting_value(bestThread) * int(bestThreadPV.size() > 2);
if (bestThreadInProvenWin)
{
// Make sure we pick the shortest mate / TB conversion
if (th->worker->rootMoves[0].score > bestThread->worker->rootMoves[0].score)
if (newThreadScore > bestThreadScore)
bestThread = th;
}
else if (bestThread->worker->rootMoves[0].score != -VALUE_INFINITE
&& bestThread->worker->rootMoves[0].score <= VALUE_TB_LOSS_IN_MAX_PLY)
else if (bestThreadInProvenLoss)
{
// Make sure we pick the shortest mated / TB conversion
if (th->worker->rootMoves[0].score != -VALUE_INFINITE
&& th->worker->rootMoves[0].score < bestThread->worker->rootMoves[0].score)
if (newThreadInProvenLoss && newThreadScore < bestThreadScore)
bestThread = th;
}
else if (th->worker->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY
|| (th->worker->rootMoves[0].score != -VALUE_INFINITE
&& th->worker->rootMoves[0].score <= VALUE_TB_LOSS_IN_MAX_PLY)
|| (th->worker->rootMoves[0].score > VALUE_TB_LOSS_IN_MAX_PLY
&& (votes[th->worker->rootMoves[0].pv[0]]
> votes[bestThread->worker->rootMoves[0].pv[0]]
|| (votes[th->worker->rootMoves[0].pv[0]]
== votes[bestThread->worker->rootMoves[0].pv[0]]
&& thread_value(th) * int(th->worker->rootMoves[0].pv.size() > 2)
> thread_value(bestThread)
* int(bestThread->worker->rootMoves[0].pv.size() > 2)))))
else if (newThreadInProvenWin || newThreadInProvenLoss
|| (newThreadScore > VALUE_TB_LOSS_IN_MAX_PLY
&& (newThreadMoveVote > bestThreadMoveVote
|| (newThreadMoveVote == bestThreadMoveVote && betterVotingValue))))
bestThread = th;
}
return bestThread;
}