并行化广度优先搜索

I just taught myself some OpenMP and this could be stupid. Basically I'm trying to parallelize a breadth first search program in c++, with each node taking a long time to process. Here's an example code:

queue<node*> q;
q.push(head);
while (!q.empty()) {
  qSize = q.size();
  for (int i = 0; i < qSize; i++) {
    node* currNode = q.front();
    q.pop();
    doStuff(currNode);
    q.push(currNode);
  }
}

处理函数 doStuff() 非常昂贵，我想对其进行并行化.但是，如果我通过将 #pragma omp parallel for 放在 for 行之前来并行化 for 循环，则在运行时会弹出各种奇怪的错误.我猜原因是这样 q.front() 和 q.push() 也将并行化，并且多个线程可能会通过相同的节点q.front()(因为它们都在任何 q.push 被处理之前就被处理了).

queue<node*> q;
q.push(head);
while (!q.empty()) {
  qSize = q.size();
  #pragma omp parallel for
  for (int i = 0; i < qSize; i++) {
    node* currNode;
    #pragma omp critical
    {
      currNode = q.front();
      q.pop();
    }
    doStuff(currNode);
    #pragma omp critical
    q.push(currNode);
  }
}