X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=5d2b39f57c8c4791dd6b28975448a55d89fa2622;hp=dee37d0dd740b7f6bb784c8cdf8eb0115282ff91;hb=9a542d96981e6cb45b6b01f17258a078cf27da36;hpb=05cfb00f26ca075ac972e320aaeabefe20599aea diff --git a/src/thread.cpp b/src/thread.cpp index dee37d0d..5d2b39f5 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -24,32 +24,32 @@ ThreadsManager Threads; // Global object definition -namespace { +namespace { extern "C" { - // init_thread() is the function which is called when a new thread is - // launched. It simply calls the idle_loop() function with the supplied - // threadID. There are two versions of this function; one for POSIX - // threads and one for Windows threads. + // start_routine() is the C function which is called when a new thread + // is launched. It simply calls idle_loop() with the supplied threadID. + // There are two versions of this function; one for POSIX threads and + // one for Windows threads. -#if !defined(_MSC_VER) +#if defined(_MSC_VER) - void* init_thread(void* threadID) { + DWORD WINAPI start_routine(LPVOID threadID) { Threads.idle_loop(*(int*)threadID, NULL); - return NULL; + return 0; } #else - DWORD WINAPI init_thread(LPVOID threadID) { + void* start_routine(void* threadID) { Threads.idle_loop(*(int*)threadID, NULL); - return 0; + return NULL; } #endif -} +} } // wake_up() wakes up the thread, normally at the beginning of the search or, @@ -115,12 +115,12 @@ void ThreadsManager::read_uci_options() { } -// init_threads() is called during startup. Initializes locks and condition -// variables and launches all threads sending them immediately to sleep. +// init() is called during startup. Initializes locks and condition variables +// and launches all threads sending them immediately to sleep. void ThreadsManager::init() { - int arg[MAX_THREADS]; + int threadID[MAX_THREADS]; // This flag is needed to properly end the threads when program exits allThreadsShouldExit = false; @@ -132,7 +132,7 @@ void ThreadsManager::init() { // Allocate pawn and material hash tables for main thread init_hash_tables(); - lock_init(&mpLock); + lock_init(&threadsLock); // Initialize thread and split point locks for (int i = 0; i < MAX_THREADS; i++) @@ -148,14 +148,14 @@ void ThreadsManager::init() { for (int i = 1; i < MAX_THREADS; i++) { threads[i].state = Thread::INITIALIZING; - arg[i] = i; + threadID[i] = i; -#if !defined(_MSC_VER) - pthread_t pthread[1]; - bool ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0); - pthread_detach(pthread[0]); +#if defined(_MSC_VER) + bool ok = (CreateThread(NULL, 0, start_routine, (LPVOID)&threadID[i], 0, NULL) != NULL); #else - bool ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL); + pthread_t pthreadID; + bool ok = (pthread_create(&pthreadID, NULL, start_routine, (void*)&threadID[i]) == 0); + pthread_detach(pthreadID); #endif if (!ok) { @@ -169,8 +169,7 @@ void ThreadsManager::init() { } -// exit_threads() is called when the program exits. It makes all the -// helper threads exit cleanly. +// exit() is called to cleanly exit the threads when the program finishes void ThreadsManager::exit() { @@ -194,7 +193,7 @@ void ThreadsManager::exit() { lock_destroy(&(threads[i].splitPoints[j].lock)); } - lock_destroy(&mpLock); + lock_destroy(&threadsLock); } @@ -241,7 +240,7 @@ bool ThreadsManager::available_slave_exists(int master) const { template void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta, Value* bestValue, Depth depth, Move threatMove, - int moveCount, MovePicker* mp, bool pvNode) { + int moveCount, MovePicker* mp, int nodeType) { assert(pos.is_ok()); assert(*bestValue >= -VALUE_INFINITE); assert(*bestValue <= *alpha); @@ -254,19 +253,12 @@ void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const V int i, master = pos.thread(); Thread& masterThread = threads[master]; - lock_grab(&mpLock); - - // If no other thread is available to help us, or if we have too many - // active split points, don't split. - if ( !available_slave_exists(master) - || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) - { - lock_release(&mpLock); + // If we already have too many active split points, don't split + if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) return; - } // Pick the next available split point object from the split point stack - SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++]; + SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints]; // Initialize the split point object splitPoint.parent = masterThread.splitPoint; @@ -276,7 +268,7 @@ void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const V splitPoint.threatMove = threatMove; splitPoint.alpha = *alpha; splitPoint.beta = beta; - splitPoint.pvNode = pvNode; + splitPoint.nodeType = nodeType; splitPoint.bestValue = *bestValue; splitPoint.mp = mp; splitPoint.moveCount = moveCount; @@ -286,27 +278,33 @@ void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const V for (i = 0; i < activeThreads; i++) splitPoint.is_slave[i] = false; - masterThread.splitPoint = &splitPoint; - // If we are here it means we are not available - assert(masterThread.state != Thread::AVAILABLE); + assert(masterThread.state == Thread::SEARCHING); + + int booked = 0; - int workersCnt = 1; // At least the master is included + // Try to allocate available threads setting state to Thread::BOOKED, this + // must be done under lock protection to avoid concurrent allocation of + // the same slave by another master. + lock_grab(&threadsLock); - // Allocate available threads setting state to THREAD_BOOKED - for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++) + for (i = 0; !Fake && i < activeThreads && booked < maxThreadsPerSplitPoint; i++) if (i != master && threads[i].is_available_to(master)) { threads[i].state = Thread::BOOKED; threads[i].splitPoint = &splitPoint; splitPoint.is_slave[i] = true; - workersCnt++; + booked++; } - assert(Fake || workersCnt > 1); + lock_release(&threadsLock); - // We can release the lock because slave threads are already booked and master is not available - lock_release(&mpLock); + // We failed to allocate even one slave, return + if (!Fake && !booked) + return; + + masterThread.activeSplitPoints++; + masterThread.splitPoint = &splitPoint; // Tell the threads that they have work to do. This will make them leave // their idle loop. @@ -315,7 +313,8 @@ void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const V { assert(i == master || threads[i].state == Thread::BOOKED); - threads[i].state = Thread::WORKISWAITING; // This makes the slave to exit from idle_loop() + // This makes the slave to exit from idle_loop() + threads[i].state = Thread::WORKISWAITING; if (useSleepingThreads && i != master) threads[i].wake_up(); @@ -329,18 +328,22 @@ void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const V idle_loop(master, &splitPoint); // We have returned from the idle loop, which means that all threads are - // finished. Update alpha and bestValue, and return. - lock_grab(&mpLock); + // finished. Update alpha and bestValue, and return. Note that changing + // state and decreasing activeSplitPoints is done under lock protection + // to avoid a race with Thread::is_available_to(). + lock_grab(&threadsLock); - *alpha = splitPoint.alpha; - *bestValue = splitPoint.bestValue; + masterThread.state = Thread::SEARCHING; masterThread.activeSplitPoints--; masterThread.splitPoint = splitPoint.parent; - pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes); - lock_release(&mpLock); + lock_release(&threadsLock); + + *alpha = splitPoint.alpha; + *bestValue = splitPoint.bestValue; + pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes); } // Explicit template instantiations -template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool); -template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool); +template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, int); +template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, int);