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Don't allocate MAX_THREADS hash tables if not necessary

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This prevent crashing on mobile devices with limited RAM,
currently with MAX_THREADS = 32 we would need 44MB that
could be too much for a poor cellphone.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-04-24 18:46:26 +01:00
parent fecefbb99c
commit 339e1b49f6
5 changed files with 40 additions and 19 deletions
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44
src/thread.cpp
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@@ -64,50 +64,48 @@ void ThreadsManager::read_uci_options() {
activeThreads = Options["Threads"].value<int>();
}
// init_threads() is called during startup. Initializes locks and condition
// variables and launches all threads sending them immediately to sleep.
void ThreadsManager::init_threads() {
int i, arg[MAX_THREADS];
bool ok;
int arg[MAX_THREADS];
// This flag is needed to properly end the threads when program exits
allThreadsShouldExit = false;
// 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();
lock_init(&mpLock);
for (i = 0; i < MAX_THREADS; i++)
// Initialize thread and split point locks
for (int i = 0; i < MAX_THREADS; i++)
{
// Initialize thread and split point locks
lock_init(&threads[i].sleepLock);
cond_init(&threads[i].sleepCond);
for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
lock_init(&(threads[i].splitPoints[j].lock));
// All threads but first should be set to THREAD_INITIALIZING
threads[i].state = (i == 0 ? THREAD_SEARCHING : THREAD_INITIALIZING);
// Not in Threads c'tor to avoid global initialization order issues
threads[i].pawnTable.init();
threads[i].materialTable.init();
}
// Create and startup the threads
for (i = 1; i < MAX_THREADS; i++)
// Create and startup all the threads but the main that is already running
for (int i = 1; i < MAX_THREADS; i++)
{
threads[i].state = THREAD_INITIALIZING;
arg[i] = i;
#if !defined(_MSC_VER)
pthread_t pthread[1];
ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0);
bool ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0);
pthread_detach(pthread[0]);
#else
ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL);
bool ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL);
#endif
if (!ok)
{
@@ -150,6 +148,22 @@ void ThreadsManager::exit_threads() {
}
// 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();
}
}
// cutoff_at_splitpoint() checks whether a beta cutoff has occurred in
// the thread's currently active split point, or in some ancestor of
// the current split point.