Question

我目前正在尝试为我的国际象棋引擎实施懒惰的SMP，这涉及在不同的核心上运行搜索算法（尽可能不同步），并且（希望）获得共享哈希表的好处。它仍然只在一个核心上运行。下面的代码（我已删除了相关的部分）。

迭代加深循环：

for( distance; distance <= depth && IDTimeS < endTime; ) {

    positionCount = 0;
    clock_t currentTime = clock();

    if( currentTime >= endTime ) {
        distance - 1;
        break;
    }      

    //multi threading testing
    int val = multi( distance, alpha, beta, false, currentTime, timeLimmit, currentDepth +1, true, z0, z1, z2 );

    //increment distance to travel (same as depth at max depth)
    distance++;
}

多线程功能：

int Ai_Logic::multi(
    int distance,
    int alpha,
    int beta,
    bool isWhite,
    long currentTime,
    long timeLimmit,
    int currentDepth,
    bool allowNull,
    ZobristH *z0,
    ZobristH *z1,
    ZobristH *z2
)
{
    auto f1 = std::async( std::launch::async, &Ai_Logic::alphaBeta, this, distance, alpha, beta, isWhite, currentTime, timeLimmit, currentDepth, allowNull, BB0, z0 );
    auto f2 = std::async( std::launch::async, &Ai_Logic::alphaBeta, this, distance-1, alpha, beta, isWhite, currentTime, timeLimmit, currentDepth, allowNull, BB1, z1 );
    auto f3 = std::async( std::launch::async, &Ai_Logic::alphaBeta, this, distance+1, alpha, beta, isWhite, currentTime, timeLimmit, currentDepth, allowNull, BB2, z2 );

    auto val  = f1.get();
    auto val2 = f2.get();
    auto val3 = f3.get();

    return val;
}

是否有一个明显的原因，我错过了为什么它仍然只使用一个核心？

Answer 1

找出至少解决我遇到的问题的方法。只要线程是在迭代加深循环之前创建的，并且在我确实获得多核使用之后加入。

std::thread t0(&Ai_Logic::alphaBeta, this, depth+1, alpha, beta, false, 0, timeLimmit, currentDepth, true, BB0, z0);
std::thread t1(&Ai_Logic::alphaBeta, this, depth-1, alpha, beta, false, 0, timeLimmit, currentDepth, true, BB1, z1);

for( distance; distance <= depth && IDTimeS < endTime; ) {

positionCount = 0;
clock_t currentTime = clock();

if( currentTime >= endTime ) {
    distance - 1;
    break;
}      

//normal alpha beta call
int val = alphaBeta(distance, alpha, beta, false, currentTime, timeLimmit, currentDepth +1, true, newBoard, mZobrist);


//increment distance to travel (same as depth at max depth)
distance++;
}

t0.join();
t1.join();

只在一个核心上运行的c ++异步？

1 个答案: