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Rewrite how threads are spawned

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Instead of creating a running std::thread and
returning, wait in Thread c'tor that the native
thread of execution goes to sleep in idle_loop().

In this way we can simplify how search is started,
because when main thread is idle we are sure also
all other threads will be idle, in any case, even
at thread creation and startup.

After lazy smp went in, we can simpify and rewrite
a lot of logic that is now no more needed. This is
hopefully the final big cleanup.

Tested for no regression at 5+0.1 with 3 threads:
LLR: 2.95 (-2.94,2.94) [-5.00,0.00]
Total: 17411 W: 3248 L: 3198 D: 10965

No functional change.
This commit is contained in:
Marco Costalba
2015-11-21 07:48:50 +01:00
parent 07e0741dfb
commit 93195555ed
6 changed files with 75 additions and 73 deletions
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25
src/thread.h
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@@ -40,20 +40,22 @@
/// entry its life time is unlimited and we don't have to care about someone
/// changing the entry under our feet.
struct Thread : public std::thread {
class Thread {
std::thread nativeThread;
Mutex mutex;
ConditionVariable sleepCondition;
bool exit, searching;
public:
Thread();
virtual ~Thread();
virtual void search();
void idle_loop();
void join();
void notify_one();
void start_searching(bool resume = false);
void wait_for_search_finished();
void wait(std::atomic_bool& b);
std::atomic_bool exit, searching, resetCalls;
Mutex mutex;
ConditionVariable sleepCondition;
Pawns::Table pawnsTable;
Material::Table materialTable;
Endgames endgames;
@@ -66,10 +68,11 @@ struct Thread : public std::thread {
HistoryStats history;
MovesStats counterMoves;
Depth completedDepth;
std::atomic_bool resetCalls;
};
/// MainThread is a derived classes used to characterize the the main one
/// MainThread is a derived class with a specific overload for the main thread
struct MainThread : public Thread {
virtual void search();
@@ -77,8 +80,8 @@ struct MainThread : public Thread {
/// ThreadPool struct handles all the threads related stuff like init, starting,
/// parking and, most importantly, launching a thread.
/// All the access to shared thread data is done through this class.
/// parking and, most importantly, launching a thread. All the access to threads
/// data is done through this class.
struct ThreadPool : public std::vector<Thread*> {
@@ -86,8 +89,8 @@ struct ThreadPool : public std::vector<Thread*> {
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&);
void read_uci_options();
int64_t nodes_searched();
};