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Refactor global variables

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This aims to remove some of the annoying global structure which Stockfish has.

Overall there is no major elo regression to be expected.

Non regression SMP STC (paused, early version):
https://tests.stockfishchess.org/tests/view/65983d7979aa8af82b9608f1
LLR: 0.23 (-2.94,2.94) <-1.75,0.25>
Total: 76232 W: 19035 L: 19096 D: 38101
Ptnml(0-2): 92, 8735, 20515, 8690, 84

Non regression STC (early version):
https://tests.stockfishchess.org/tests/view/6595b3a479aa8af82b95da7f
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 185344 W: 47027 L: 46972 D: 91345
Ptnml(0-2): 571, 21285, 48943, 21264, 609

Non regression SMP STC:
https://tests.stockfishchess.org/tests/view/65a0715c79aa8af82b96b7e4
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 142936 W: 35761 L: 35662 D: 71513
Ptnml(0-2): 209, 16400, 38135, 16531, 193

These global structures/variables add hidden dependencies and allow data
to be mutable from where it shouldn't it be (i.e. options). They also
prevent Stockfish from internal selfplay, which would be a nice thing to
be able to do, i.e. instantiate two Stockfish instances and let them
play against each other. It will also allow us to make Stockfish a
library, which can be easier used on other platforms.

For consistency with the old search code, `thisThread` has been kept,
even though it is not strictly necessary anymore. This the first major
refactor of this kind (in recent time), and future changes are required,
to achieve the previously described goals. This includes cleaning up the
dependencies, transforming the network to be self contained and coming
up with a plan to deal with proper tablebase memory management (see
comments for more information on this).

The removal of these global structures has been discussed in parts with
Vondele and Sopel.

closes https://github.com/official-stockfish/Stockfish/pull/4968

No functional change
This commit is contained in:
Disservin
2024-01-08 19:48:46 +01:00
parent 6deb88728f
commit a107910951
27 changed files with 1200 additions and 1001 deletions
Download Patch File Download Diff File Expand all files Collapse all files

134
src/thread.cpp
View File

@@ -23,9 +23,8 @@
#include <cmath>
#include <cstdlib>
#include <deque>
#include <initializer_list>
#include <unordered_map>
#include <memory>
#include <unordered_map>
#include <utility>
#include "evaluate.h"
@@ -33,18 +32,21 @@
#include "movegen.h"
#include "search.h"
#include "syzygy/tbprobe.h"
#include "timeman.h"
#include "tt.h"
#include "uci.h"
#include "types.h"
#include "ucioption.h"
namespace Stockfish {
ThreadPool Threads; // Global object
// 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(size_t n) :
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();
@@ -62,24 +64,6 @@ Thread::~Thread() {
stdThread.join();
}
// Reset histories, usually before a new game
void Thread::clear() {
counterMoves.fill(Move::none());
mainHistory.fill(0);
captureHistory.fill(0);
pawnHistory.fill(0);
correctionHistory.fill(0);
for (bool inCheck : {false, true})
for (StatsType c : {NoCaptures, Captures})
for (auto& to : continuationHistory[inCheck][c])
for (auto& h : to)
h->fill(-71);
}
// Wakes up the thread that will start the search
void Thread::start_searching() {
mutex.lock();
@@ -108,7 +92,7 @@ void Thread::idle_loop() {
// 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 (Options["Threads"] > 8)
if (nthreads > 8)
WinProcGroup::bindThisThread(idx);
while (true)
@@ -123,36 +107,41 @@ void Thread::idle_loop() {
lk.unlock();
search();
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(size_t requested) {
void ThreadPool::set(Search::SharedState sharedState) {
if (threads.size() > 0) // destroy any existing thread(s)
{
main()->wait_for_search_finished();
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 MainThread(0));
threads.push_back(new Thread(
sharedState, std::unique_ptr<Search::ISearchManager>(new Search::SearchManager()), 0));
while (threads.size() < requested)
threads.push_back(new Thread(threads.size()));
threads.push_back(new Thread(
sharedState, std::unique_ptr<Search::ISearchManager>(new Search::NullSearchManager()),
threads.size()));
clear();
// Reallocate the hash with the new threadpool size
TT.resize(size_t(Options["Hash"]));
main_thread()->wait_for_search_finished();
// Init thread number dependent search params.
Search::init();
// Reallocate the hash with the new threadpool size
sharedState.tt.resize(sharedState.options["Hash"], requested);
}
}
@@ -161,28 +150,31 @@ void ThreadPool::set(size_t requested) {
void ThreadPool::clear() {
for (Thread* th : threads)
th->clear();
th->worker->clear();
main()->callsCnt = 0;
main()->bestPreviousScore = VALUE_INFINITE;
main()->bestPreviousAverageScore = VALUE_INFINITE;
main()->previousTimeReduction = 1.0;
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(Position& pos,
StateListPtr& states,
const Search::LimitsType& limits,
bool ponderMode) {
void ThreadPool::start_thinking(const OptionsMap& options,
Position& pos,
StateListPtr& states,
Search::LimitsType limits,
bool ponderMode) {
main()->wait_for_search_finished();
main_thread()->wait_for_search_finished();
main_manager()->stopOnPonderhit = stop = false;
main_manager()->ponder = ponderMode;
increaseDepth = true;
main()->stopOnPonderhit = stop = false;
increaseDepth = true;
main()->ponder = ponderMode;
Search::Limits = limits;
Search::RootMoves rootMoves;
for (const auto& m : MoveList<LEGAL>(pos))
@@ -191,7 +183,7 @@ void ThreadPool::start_thinking(Position& pos,
rootMoves.emplace_back(m);
if (!rootMoves.empty())
Tablebases::rank_root_moves(pos, rootMoves);
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.
@@ -207,15 +199,17 @@ void ThreadPool::start_thinking(Position& pos,
// since they are read-only.
for (Thread* th : threads)
{
th->nodes = th->tbHits = th->nmpMinPly = th->bestMoveChanges = 0;
th->rootDepth = th->completedDepth = 0;
th->rootMoves = rootMoves;
th->rootPos.set(pos.fen(), pos.is_chess960(), &th->rootState, th);
th->rootState = setupStates->back();
th->rootSimpleEval = Eval::simple_eval(pos, pos.side_to_move());
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->rootSimpleEval = Eval::simple_eval(pos, pos.side_to_move());
}
main()->start_searching();
main_thread()->start_searching();
}
Thread* ThreadPool::get_best_thread() const {
@@ -226,30 +220,32 @@ Thread* ThreadPool::get_best_thread() const {
// Find the minimum score of all threads
for (Thread* th : threads)
minScore = std::min(minScore, th->rootMoves[0].score);
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->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
return (th->worker->rootMoves[0].score - minScore + 14) * int(th->worker->completedDepth);
};
for (Thread* th : threads)
votes[th->rootMoves[0].pv[0]] += thread_value(th);
votes[th->worker->rootMoves[0].pv[0]] += thread_value(th);
for (Thread* th : threads)
if (std::abs(bestThread->rootMoves[0].score) >= VALUE_TB_WIN_IN_MAX_PLY)
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->rootMoves[0].score > bestThread->rootMoves[0].score)
if (th->worker->rootMoves[0].score > bestThread->worker->rootMoves[0].score)
bestThread = th;
}
else if (th->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY
|| (th->rootMoves[0].score > VALUE_TB_LOSS_IN_MAX_PLY
&& (votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]]
|| (votes[th->rootMoves[0].pv[0]] == votes[bestThread->rootMoves[0].pv[0]]
&& thread_value(th) * int(th->rootMoves[0].pv.size() > 2)
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->rootMoves[0].pv.size() > 2)))))
* int(bestThread->worker->rootMoves[0].pv.size() > 2)))))
bestThread = th;
return bestThread;
@@ -257,7 +253,7 @@ Thread* ThreadPool::get_best_thread() const {
// Start non-main threads
// Will be invoked by main thread after it has started searching
void ThreadPool::start_searching() {
for (Thread* th : threads)