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BadFish/src/thread.cpp
Disservin a5675f19d8 Remove global TB variables from search.cpp
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
2024-01-17 18:05:00 +01:00

272 lines
9.1 KiB
C++

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