read_evaluation_uci_options(pos.side_to_move());
Threads.read_uci_options();
- // If needed allocate pawn and material hash tables and adjust TT size
+ // Allocate pawn and material hash tables if number of active threads
+ // increased and set a new TT size if changed.
Threads.init_hash_tables();
TT.set_size(Options["Hash"].value<int>());
while (true)
{
- // Slave threads can exit as soon as AllThreadsShouldExit raises,
+ // Slave threads can exit as soon as allThreadsShouldExit flag raises,
// master should exit as last one.
if (allThreadsShouldExit)
{
return;
}
- // If we are not thinking, wait for a condition to be signaled
+ // If we are not searching, wait for a condition to be signaled
// instead of wasting CPU time polling for work.
while ( threadID >= activeThreads
|| threads[threadID].state == Thread::INITIALIZING
// Grab the lock to avoid races with Thread::wake_up()
lock_grab(&threads[threadID].sleepLock);
- // If we are master and all slaves have finished do not go to sleep
+ // If we are master and all slaves have finished don't go to sleep
for (i = 0; sp && i < activeThreads && !sp->is_slave[i]; i++) {}
allFinished = (i == activeThreads);
break;
}
- // Do sleep here after retesting sleep conditions
+ // Do sleep after retesting sleep conditions under lock protection, in
+ // particular we need to avoid a deadlock in case a master thread has,
+ // in the meanwhile, allocated us and sent the wake_up() call before we
+ // had the chance to grab the lock.
if (threadID >= activeThreads || threads[threadID].state == Thread::AVAILABLE)
cond_wait(&threads[threadID].sleepCond, &threads[threadID].sleepLock);
threads[threadID].state = Thread::SEARCHING;
// Copy split point position and search stack and call search()
- // with SplitPoint template parameter set to true.
SearchStack ss[PLY_MAX_PLUS_2];
SplitPoint* tsp = threads[threadID].splitPoint;
Position pos(*tsp->pos, threadID);
if (allFinished)
{
- // Because sp->slaves[] is reset under lock protection,
+ // Because sp->is_slave[] is reset under lock protection,
// be sure sp->lock has been released before to return.
lock_grab(&(sp->lock));
lock_release(&(sp->lock));
-
- // 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(threads[threadID].state == Thread::AVAILABLE);
return;
}
}