Unfortunately std::condition_variable::wait_for()
is not accurate in general case and the timer thread
can wake up also after tens or even hundreds of
millisecs after time has elapsded. CPU load, process
priorities, number of concurrent threads, even from
other processes, will have effect upon it.
Even official documentation says: "This function may
block for longer than timeout_duration due to scheduling
or resource contention delays."
So retire timer and use a polling scheme based on a
local thread counter that counts search() calls and
a small trick to keep polling frequency constant,
independently from the number of threads.
Tested for no regression at very fast TC 2+0.05 th 7:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 32969 W: 6720 L: 6620 D: 19629
TC 2+0.05 th 1:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 7765 W: 1917 L: 1765 D: 4083
And at STC TC, both single thread
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 15587 W: 3036 L: 2905 D: 9646
And with 7 threads
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 8149 W: 1367 L: 1227 D: 5555
bench:
8639247
Value value_from_tt(Value v, int ply);
void update_pv(Move* pv, Move move, Move* childPv);
void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
+ void check_time();
} // namespace
}
}
- Threads.timer->run = true;
- Threads.timer->notify_one(); // Start the recurring timer
-
search(true); // Let's start searching!
- // Stop the threads and the timer
+ // Stop the threads
Signals.stop = true;
- Threads.timer->run = false;
// Wait until all threads have finished
for (Thread* th : Threads)
bestValue = -VALUE_INFINITE;
ss->ply = (ss-1)->ply + 1;
+ // Check for available remaining time
+ if (thisThread->resetCallsCnt.load(std::memory_order_relaxed))
+ {
+ thisThread->resetCallsCnt = false;
+ thisThread->callsCnt = 0;
+ }
+ if (++thisThread->callsCnt > 4096)
+ {
+ for (Thread* th : Threads)
+ th->resetCallsCnt = true;
+
+ check_time();
+ }
+
// Used to send selDepth info to GUI
if (PvNode && thisThread->maxPly < ss->ply)
thisThread->maxPly = ss->ply;
return best;
}
+
+ // check_time() is used to print debug info and, more importantly, to detect
+ // when we are out of available time and thus stop the search.
+
+ void check_time() {
+
+ static TimePoint lastInfoTime = now();
+
+ int elapsed = Time.elapsed();
+ TimePoint tick = Limits.startTime + elapsed;
+
+ if (tick - lastInfoTime >= 1000)
+ {
+ lastInfoTime = tick;
+ dbg_print();
+ }
+
+ // An engine may not stop pondering until told so by the GUI
+ if (Limits.ponder)
+ return;
+
+ if (Limits.use_time_management())
+ {
+ bool stillAtFirstMove = Signals.firstRootMove.load(std::memory_order_relaxed)
+ && !Signals.failedLowAtRoot.load(std::memory_order_relaxed)
+ && elapsed > Time.available() * 3 / 4;
+
+ if (stillAtFirstMove || elapsed > Time.maximum() - 10)
+ Signals.stop = true;
+ }
+ else if (Limits.movetime && elapsed >= Limits.movetime)
+ Signals.stop = true;
+
+ else if (Limits.nodes && Threads.nodes_searched() >= Limits.nodes)
+ Signals.stop = true;
+ }
+
} // namespace
return false;
}
-
-
-/// TimerThread::check_time() is called by when the timer triggers. It is used
-/// to print debug info and, more importantly, to detect when we are out of
-/// available time and thus stop the search.
-
-void TimerThread::check_time() {
-
- static TimePoint lastInfoTime = now();
- int elapsed = Time.elapsed();
-
- if (now() - lastInfoTime >= 1000)
- {
- lastInfoTime = now();
- dbg_print();
- }
-
- // An engine may not stop pondering until told so by the GUI
- if (Limits.ponder)
- return;
-
- if (Limits.use_time_management())
- {
- bool stillAtFirstMove = Signals.firstRootMove
- && !Signals.failedLowAtRoot
- && elapsed > Time.available() * 3 / 4;
-
- if ( stillAtFirstMove
- || elapsed > Time.maximum() - 2 * TimerThread::Resolution)
- Signals.stop = true;
- }
- else if (Limits.movetime && elapsed >= Limits.movetime)
- Signals.stop = true;
-
- else if (Limits.nodes && Threads.nodes_searched() >= Limits.nodes)
- Signals.stop = true;
-}
/// typically in an async fashion e.g. to stop the search by the GUI.
struct SignalsType {
- std::atomic<bool> stop, stopOnPonderhit, firstRootMove, failedLowAtRoot;
+ std::atomic_bool stop, stopOnPonderhit, firstRootMove, failedLowAtRoot;
};
typedef std::unique_ptr<std::stack<StateInfo>> StateStackPtr;
// ThreadBase::wait() set the thread to sleep until 'condition' turns true
-void ThreadBase::wait(std::atomic<bool>& condition) {
+void ThreadBase::wait(std::atomic_bool& condition) {
std::unique_lock<Mutex> lk(mutex);
sleepCondition.wait(lk, [&]{ return bool(condition); });
// ThreadBase::wait_while() set the thread to sleep until 'condition' turns false
-void ThreadBase::wait_while(std::atomic<bool>& condition) {
+void ThreadBase::wait_while(std::atomic_bool& condition) {
std::unique_lock<Mutex> lk(mutex);
sleepCondition.wait(lk, [&]{ return !condition; });
Thread::Thread() {
- searching = false;
- maxPly = 0;
+ searching = resetCallsCnt = false;
+ maxPly = callsCnt = 0;
history.clear();
counterMoves.clear();
idx = Threads.size(); // Starts from 0
}
-// TimerThread::idle_loop() is where the timer thread waits Resolution milliseconds
-// and then calls check_time(). When not searching, thread sleeps until it's woken up.
-
-void TimerThread::idle_loop() {
-
- while (!exit)
- {
- std::unique_lock<Mutex> lk(mutex);
-
- if (!exit)
- sleepCondition.wait_for(lk, std::chrono::milliseconds(run ? Resolution : INT_MAX));
-
- lk.unlock();
-
- if (!exit && run)
- check_time();
- }
-}
-
-
// Thread::idle_loop() is where the thread is parked when it has no work to do
void Thread::idle_loop() {
void ThreadPool::init() {
- timer = new_thread<TimerThread>();
push_back(new_thread<MainThread>());
read_uci_options();
}
void ThreadPool::exit() {
- delete_thread(timer); // As first because check_time() accesses threads data
- timer = nullptr;
-
for (Thread* th : *this)
delete_thread(th);
virtual ~ThreadBase() = default;
virtual void idle_loop() = 0;
void notify_one();
- void wait(std::atomic<bool>& b);
- void wait_while(std::atomic<bool>& b);
+ void wait(std::atomic_bool& b);
+ void wait_while(std::atomic_bool& b);
Mutex mutex;
ConditionVariable sleepCondition;
- std::atomic<bool> exit;
+ std::atomic_bool exit;
};
Material::Table materialTable;
Endgames endgames;
size_t idx, PVIdx;
- int maxPly;
- std::atomic<bool> searching;
+ int maxPly, callsCnt;
+ std::atomic_bool searching, resetCallsCnt;
Position rootPos;
Search::RootMoveVector rootMoves;
};
-/// MainThread and TimerThread are derived classes used to characterize the two
-/// special threads: the main one and the recurring timer.
+/// MainThread is a derived classes used to characterize the the main one
struct MainThread : public Thread {
MainThread() { thinking = true; } // Avoid a race with start_thinking()
virtual void idle_loop();
void join();
void think();
- std::atomic<bool> thinking;
-};
-
-struct TimerThread : public ThreadBase {
-
- static const int Resolution = 5; // Millisec between two check_time() calls
-
- virtual void idle_loop();
- void check_time();
-
- bool run = false;
+ std::atomic_bool thinking;
};
struct ThreadPool : public std::vector<Thread*> {
- void init(); // No constructor and destructor, threads rely on globals that should
+ void init(); // No constructor and destructor, threads rely on globals that should
void exit(); // be initialized and valid during the whole thread lifetime.
MainThread* main() { return static_cast<MainThread*>(at(0)); }
void read_uci_options();
void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
int64_t nodes_searched();
- TimerThread* timer;
};
extern ThreadPool Threads;