diff --git a/src/search.cpp b/src/search.cpp index 1c271561..f259c8fb 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -2950,7 +2950,6 @@ namespace { assert(ActiveThreads > 1); SplitPoint* splitPoint; - int i; lock_grab(&MPLock); @@ -2983,34 +2982,42 @@ namespace { splitPoint->cpus = 1; splitPoint->pos = &p; splitPoint->parentSstack = sstck; - for (i = 0; i < ActiveThreads; i++) + for (int i = 0; i < ActiveThreads; i++) splitPoint->slaves[i] = 0; - // Copy the tail of current search stack to the master thread - memcpy(splitPoint->sstack[master] + ply - 1, sstck + ply - 1, 3 * sizeof(SearchStack)); + Threads[master].idle = false; Threads[master].splitPoint = splitPoint; - // Make copies of the current position and search stack for each thread - for (i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++) + // Allocate available threads setting idle flag to false + for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++) if (thread_is_available(i, master)) { - memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 3 * sizeof(SearchStack)); + Threads[i].idle = false; Threads[i].splitPoint = splitPoint; splitPoint->slaves[i] = 1; splitPoint->cpus++; } + assert(splitPoint->cpus > 1); + + // We can release the lock because master and slave threads are already booked + lock_release(&MPLock); + + // Copy the tail of current search stack to the master thread + memcpy(splitPoint->sstack[master] + ply - 1, sstck + ply - 1, 3 * sizeof(SearchStack)); + // Tell the threads that they have work to do. This will make them leave - // their idle loop. - for (i = 0; i < ActiveThreads; i++) + // their idle loop. Also copy search stack tail for each slave thread. + for (int i = 0; i < ActiveThreads; i++) + { if (i == master || splitPoint->slaves[i]) { Threads[i].workIsWaiting = true; - Threads[i].idle = false; Threads[i].stop = false; } - - lock_release(&MPLock); + if (splitPoint->slaves[i]) + memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 3 * sizeof(SearchStack)); + } // Everything is set up. The master thread enters the idle loop, from // which it will instantly launch a search, because its workIsWaiting