试图加速这个 for 循环，但我不能使用 Callable 实现

Question

这是顺序循环：

  private boolean canSpawnVehicle(SpawnPoint spawnPoint) {

// TODO: can be made much faster.

Rectangle2D noVehicleZone = spawnPoint.getNoVehicleZone();

for(VehicleSimView vehicle : vinToVehicles.values()) {

  if (vehicle.getShape().intersects(noVehicleZone)) {

    return false;

  }

}

return true;

}

这是我对执行程序服务和可调用实现类进行线程化的尝试：

  private boolean canSpawnVehicle(SpawnPoint spawnPoint) throws ExecutionException, InterruptedException {

  // TODO: can be made much faster.

  Rectangle2D noVehicleZone = spawnPoint.getNoVehicleZone();

  ExecutorService executor = Executors.newFixedThreadPool(6);

  Future<Boolean> future;

  for (VehicleSimView vehicle : vinToVehicles.values()) {

      future = executor.submit(new CanSpawnThread(vehicle, noVehicleZone));

      if(!future.get()){

          return false;

      }

  }

  executor.shutdown();

  return true;

}

这是线程类：

公共类 CanSpawnThread 实现 Callable {

private VehicleSimView vehicle;

private Rectangle2D noVehicleZone;

public CanSpawnThread(VehicleSimView vehicle, Rectangle2D noVehicleZone){

    this.vehicle = vehicle;

    this.noVehicleZone = noVehicleZone;

}

public Boolean call() {

    boolean can = true;

    if (vehicle.getShape().intersects(noVehicleZone)){

        can = false;

    }

        return can;

}

}

Answer 1

您可以尝试使用 parallelStream 假设列表有足够的项目来证明线程的合理性。不过我还没有测试过这个。private boolean canSpawnVehicle(SpawnPoint spawnPoint) {&nbsp; &nbsp; Rectangle2D noVehicleZone = spawnPoint.getNoVehicleZone();&nbsp; &nbsp; Optional result = vinToVehicles.values().parallelStream().filter(v -> !v.getShape().intersects(noVehicleZone)).findFirst();&nbsp; &nbsp; return !result.isPresent();}

Answer 2

您提交任务并等待完成。以这种方式，每件事都是连续的，因此您无法提高性能。提交所有任务，然后等待完成并检查结果。像这样：&nbsp;private boolean canSpawnVehicle(SpawnPoint spawnPoint) throws ExecutionException, InterruptedException {&nbsp; // TODO: can be made much faster.&nbsp; Rectangle2D noVehicleZone = spawnPoint.getNoVehicleZone();&nbsp; ExecutorService executor = Executors.newFixedThreadPool(6);&nbsp; List<Future<Boolean>> futures = new ArrayList();&nbsp; for (VehicleSimView vehicle : vinToVehicles.values()) {&nbsp; &nbsp; &nbsp; futures.add(executor.submit(new CanSpawnThread(vehicle, noVehicleZone)));&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; }&nbsp; for(Future<Boolean> future : futures) {&nbsp; &nbsp; &nbsp; &nbsp;if(!future.get()) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return false;&nbsp; &nbsp; &nbsp; &nbsp;}&nbsp; }&nbsp; executor.shutdown();&nbsp; return true;}

Answer 3

看循环：for (VehicleSimView vehicle : vinToVehicles.values()) {&nbsp; &nbsp; &nbsp; future = executor.submit(new CanSpawnThread(vehicle, noVehicleZone));&nbsp; &nbsp; &nbsp; if(!future.get()){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return false;&nbsp; &nbsp; &nbsp; }&nbsp; }您正在提交给执行者，然后等待未来完成，然后继续并提交下一个。这仍然只是一个顺序循环。将所有可调用对象提交给执行程序，将Futures存储在列表中，然后检查列表的元素以查看它们是否已完成。或者，更好的是使用 a CompletionService，它会按照它们完成的顺序返回给你。一旦你找到一个返回 false 的 Future，取消所有其他的并返回。