X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=d845fdf2e4183f2fdaa10bb656b66d1ab6439749;hp=e1330396d0007f30815c3ba95d2142c9ad8bb1d7;hb=83d8fe2d59bad718de70b00ac2c8fddfadda76b5;hpb=5b35c149e833e365c2afb8039ca5c658abc53081 diff --git a/src/thread.cpp b/src/thread.cpp index e1330396..d845fdf2 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -27,23 +27,23 @@ ThreadsManager Threads; // Global object definition namespace { extern "C" { // start_routine() is the C function which is called when a new thread - // is launched. It simply calls idle_loop() with the supplied threadID. + // is launched. It simply calls idle_loop() of the supplied thread. // There are two versions of this function; one for POSIX threads and // one for Windows threads. #if defined(_MSC_VER) - DWORD WINAPI start_routine(LPVOID threadID) { + DWORD WINAPI start_routine(LPVOID thread) { - Threads.idle_loop(*(int*)threadID, NULL); + ((Thread*)thread)->idle_loop(NULL); return 0; } #else - void* start_routine(void* threadID) { + void* start_routine(void* thread) { - Threads.idle_loop(*(int*)threadID, NULL); + ((Thread*)thread)->idle_loop(NULL); return NULL; } @@ -63,9 +63,8 @@ void Thread::wake_up() { } -// cutoff_occurred() checks whether a beta cutoff has occurred in -// the thread's currently active split point, or in some ancestor of -// the current split point. +// cutoff_occurred() checks whether a beta cutoff has occurred in the current +// active split point, or in some ancestor of the split point. bool Thread::cutoff_occurred() const { @@ -85,7 +84,7 @@ bool Thread::cutoff_occurred() const { bool Thread::is_available_to(int master) const { - if (state != AVAILABLE) + if (is_searching) return false; // Make a local copy to be sure doesn't become zero under our feet while @@ -111,30 +110,47 @@ void ThreadsManager::read_uci_options() { maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value(); minimumSplitDepth = Options["Minimum Split Depth"].value() * ONE_PLY; useSleepingThreads = Options["Use Sleeping Threads"].value(); - activeThreads = Options["Threads"].value(); + + set_size(Options["Threads"].value()); } -// init() is called during startup. Initializes locks and condition variables -// and launches all threads sending them immediately to sleep. +// set_size() changes the number of active threads and raises do_sleep flag for +// all the unused threads that will go immediately to sleep. -void ThreadsManager::init() { +void ThreadsManager::set_size(int cnt) { - int threadID[MAX_THREADS]; + assert(cnt > 0 && cnt <= MAX_THREADS); - // This flag is needed to properly end the threads when program exits - allThreadsShouldExit = false; + activeThreads = cnt; + + for (int i = 0; i < MAX_THREADS; i++) + if (i < activeThreads) + { + // Dynamically allocate pawn and material hash tables according to the + // number of active threads. This avoids preallocating memory for all + // possible threads if only few are used as, for instance, on mobile + // devices where memory is scarce and allocating for MAX_THREADS could + // even result in a crash. + threads[i].pawnTable.init(); + threads[i].materialTable.init(); + + threads[i].do_sleep = false; + } + else + threads[i].do_sleep = true; +} - // Threads will sent to sleep as soon as created, only main thread is kept alive - activeThreads = 1; - threads[0].state = Thread::SEARCHING; - // Allocate pawn and material hash tables for main thread - init_hash_tables(); +// init() is called during startup. Initializes locks and condition variables +// and launches all threads sending them immediately to sleep. +void ThreadsManager::init() { + + // Initialize threads lock, used when allocating slaves during splitting lock_init(&threadsLock); - // Initialize thread and split point locks + // Initialize sleep and split point locks for (int i = 0; i < MAX_THREADS; i++) { lock_init(&threads[i].sleepLock); @@ -144,48 +160,60 @@ void ThreadsManager::init() { lock_init(&(threads[i].splitPoints[j].lock)); } - // Create and startup all the threads but the main that is already running + // Initialize main thread's associated data + threads[0].is_searching = true; + threads[0].threadID = 0; + set_size(1); // This makes all the threads but the main to go to sleep + + // Create and launch all the threads but the main that is already running, + // threads will go immediately to sleep. for (int i = 1; i < MAX_THREADS; i++) { - threads[i].state = Thread::INITIALIZING; - threadID[i] = i; + threads[i].is_searching = false; + threads[i].threadID = i; #if defined(_MSC_VER) - bool ok = (CreateThread(NULL, 0, start_routine, (LPVOID)&threadID[i], 0, NULL) != NULL); + threads[i].handle = CreateThread(NULL, 0, start_routine, (LPVOID)&threads[i], 0, NULL); + bool ok = (threads[i].handle != NULL); #else - pthread_t pthreadID; - bool ok = (pthread_create(&pthreadID, NULL, start_routine, (void*)&threadID[i]) == 0); - pthread_detach(pthreadID); + bool ok = (pthread_create(&threads[i].handle, NULL, start_routine, (void*)&threads[i]) == 0); #endif + if (!ok) { - std::cout << "Failed to create thread number " << i << std::endl; + std::cerr << "Failed to create thread number " << i << std::endl; ::exit(EXIT_FAILURE); } - - // Wait until the thread has finished launching and is gone to sleep - while (threads[i].state == Thread::INITIALIZING) {} } } -// exit() is called to cleanly exit the threads when the program finishes +// exit() is called to cleanly terminate the threads when the program finishes void ThreadsManager::exit() { - // Force the woken up threads to exit idle_loop() and hence terminate - allThreadsShouldExit = true; + // Wake up all the slave threads at once. This is faster than "wake and wait" + // for each thread and avoids a rare crash once every 10K games under Linux. + for (int i = 1; i < MAX_THREADS; i++) + { + threads[i].do_terminate = true; + threads[i].wake_up(); + } for (int i = 0; i < MAX_THREADS; i++) { - // Wake up all the threads and waits for termination if (i != 0) { - threads[i].wake_up(); - while (threads[i].state != Thread::TERMINATED) {} + // Wait for slave termination +#if defined(_MSC_VER) + WaitForSingleObject(threads[i].handle, 0); + CloseHandle(threads[i].handle); +#else + pthread_join(threads[i].handle, NULL); +#endif } - // Now we can safely destroy the locks and wait conditions + // Now we can safely destroy locks and wait conditions lock_destroy(&threads[i].sleepLock); cond_destroy(&threads[i].sleepCond); @@ -197,22 +225,6 @@ void ThreadsManager::exit() { } -// init_hash_tables() dynamically allocates pawn and material hash tables -// according to the number of active threads. This avoids preallocating -// memory for all possible threads if only few are used as, for instance, -// on mobile devices where memory is scarce and allocating for MAX_THREADS -// threads could even result in a crash. - -void ThreadsManager::init_hash_tables() { - - for (int i = 0; i < activeThreads; i++) - { - threads[i].pawnTable.init(); - threads[i].materialTable.init(); - } -} - - // available_slave_exists() tries to find an idle thread which is available as // a slave for the thread with threadID "master". @@ -258,88 +270,84 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b return bestValue; // Pick the next available split point object from the split point stack - SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints]; + SplitPoint* sp = masterThread.splitPoints + masterThread.activeSplitPoints; // Initialize the split point object - splitPoint.parent = masterThread.splitPoint; - splitPoint.master = master; - splitPoint.is_betaCutoff = false; - splitPoint.depth = depth; - splitPoint.threatMove = threatMove; - splitPoint.alpha = alpha; - splitPoint.beta = beta; - splitPoint.nodeType = nodeType; - splitPoint.bestValue = bestValue; - splitPoint.mp = mp; - splitPoint.moveCount = moveCount; - splitPoint.pos = &pos; - splitPoint.nodes = 0; - splitPoint.ss = ss; + sp->parent = masterThread.splitPoint; + sp->master = master; + sp->is_betaCutoff = false; + sp->depth = depth; + sp->threatMove = threatMove; + sp->alpha = alpha; + sp->beta = beta; + sp->nodeType = nodeType; + sp->bestValue = bestValue; + sp->mp = mp; + sp->moveCount = moveCount; + sp->pos = &pos; + sp->nodes = 0; + sp->ss = ss; for (i = 0; i < activeThreads; i++) - splitPoint.is_slave[i] = false; + sp->is_slave[i] = false; // If we are here it means we are not available - assert(masterThread.state == Thread::SEARCHING); + assert(masterThread.is_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. + // Try to allocate available threads and ask them to start searching setting + // the state to Thread::WORKISWAITING, this must be done under lock protection + // to avoid concurrent allocation of the same slave by another master. lock_grab(&threadsLock); - for (i = 0; !Fake && i < activeThreads && booked < maxThreadsPerSplitPoint; i++) + for (i = 0; !Fake && i < activeThreads && workersCnt < 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; - booked++; + workersCnt++; + sp->is_slave[i] = true; + threads[i].splitPoint = sp; + + // This makes the slave to exit from idle_loop() + threads[i].is_searching = true; + + if (useSleepingThreads) + threads[i].wake_up(); } lock_release(&threadsLock); // We failed to allocate even one slave, return - if (!Fake && !booked) + if (!Fake && workersCnt == 1) return bestValue; + masterThread.splitPoint = sp; masterThread.activeSplitPoints++; - masterThread.splitPoint = &splitPoint; - - // Tell the threads that they have some work to do. This will make them leave - // their idle loop. - for (i = 0; i < activeThreads; i++) - if (i == master || splitPoint.is_slave[i]) - { - assert(i == master || threads[i].state == Thread::BOOKED); - // This makes the slave to exit from idle_loop() - threads[i].state = Thread::WORKISWAITING; + // Everything is set up. The master thread enters the idle loop, from which + // it will instantly launch a search, because its is_searching flag is set. + // We pass the split point as a parameter to the idle loop, which means that + // the thread will return from the idle loop when all slaves have finished + // their work at this split point. + masterThread.idle_loop(sp); - if (useSleepingThreads && i != master) - threads[i].wake_up(); - } - - // Everything is set up. The master thread enters the idle loop, from - // which it will instantly launch a search, because its state is - // THREAD_WORKISWAITING. We send the split point as a second parameter to the - // idle loop, which means that the main thread will return from the idle - // loop when all threads have finished their work at this split point. - idle_loop(master, &splitPoint); + // In helpful master concept a master can help only a sub-tree, and + // because here is all finished is not possible master is booked. + assert(!masterThread.is_searching); // We have returned from the idle loop, which means that all threads are // finished. Note that changing state and decreasing activeSplitPoints is done // under lock protection to avoid a race with Thread::is_available_to(). lock_grab(&threadsLock); - masterThread.state = Thread::SEARCHING; + masterThread.is_searching = true; masterThread.activeSplitPoints--; - masterThread.splitPoint = splitPoint.parent; lock_release(&threadsLock); - pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes); - return splitPoint.bestValue; + masterThread.splitPoint = sp->parent; + pos.set_nodes_searched(pos.nodes_searched() + sp->nodes); + + return sp->bestValue; } // Explicit template instantiations