后台线程上的节流CPU使用率 [英] Throttle CPU usage on background thread

问题描述

我有一个占用大量CPU的任务，我希望它使用更少的CPU并占用更多时间.

I have a CPU intensive task and I want it to use less CPU and take up more time.

在启动时，我正在将大量SCNNode加载到场景中.它占用了大量内存，我希望它以安全的速率进行处理，而不是使系统滞后或使系统崩溃.

I'm loading a massive amount of SCNNodes to a scene at start-up. It takes up a lot of memory, and I'd like it to work on it at a safe rate instead of lagging up my system or potentially crashing it.

这是我用来加载节点的代码.

Here's the code I'm using to load the nodes.

dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^(void){
    NSLog(@"Start Loading Level");
    SCNNode *cameraNode = [SCNNode node];
    cameraNode.camera = [SCNCamera camera];
    cameraNode.camera.zFar = 5000;
    cameraNode.position = SCNVector3Make(0, 3000, 0);
    cameraNode.rotation = SCNVector4Make(1, 0, 0, -M_PI_2);
    [scene.rootNode addChildNode:cameraNode];
    for (int i = 0; i < 100000; i++)
    {
        int side = 3000;
        SCNNode *node = [SCNNode node];
        node.geometry = [SCNBox boxWithWidth:1 height:1 length:1 chamferRadius:0];
        node.position = SCNVector3Make(arc4random_uniform(side) - side / 2.0,
                                       0,
                                       arc4random_uniform(side) - side / 2.0);
        [scene.rootNode addChildNode:node];
    }
    dispatch_async(dispatch_get_main_queue(), ^(void){
        NSLog(@"Finished");
    });
});

以下是统计数据:

推荐答案

这可能不是最好的方法，但是您是否看过prepareobject:?

It might not be the best way to do this, but have you looked at prepareobject:?

创建NSObjects本身不是什么大问题，但是准备几何并将其添加到场景中可能不是问题.如果将此步骤推迟到辅助线程，则可以节省一些CPU，并使场景直到准备好添加节点时才停止.

Creating the NSObjects themselves shouldn't be that much of a problem, but preparing the geometry and adding it to the scene probably is. Bu deffering this step to a secondary thread you'll save some CPU and make the scene not stop until the node is ready to be added.

每个节点准备就绪后，(完成处理程序)只需将其添加到场景中即可.我不会限制负载，但是对于您的其余应用程序，它至少会以一种更安全的方式处理它.

Once each node is ready, (completion handler) just add it to the scene. I won't throttle the loading, but it will at least handle it in a safer way for the rest of your app.

https://developer.apple.com/library/prerelease/ios/documentation/SceneKit/Reference/SCNSceneRenderer_Protocol/index.html#//apple_ref/occ/intfm/SCNSceneRenderer/prepareObjects:withCompletionHandler :

-(void)prepareLevel{
    // Mutable Array to save the nodes
    NSMutableArray *nodes = [[NSMutableArray alloc] init];

    for (int i = 0; i < 100000; i++)
    {
        int side = 3000;
        SCNNode *node = [SCNNode node];
        node.geometry = [SCNBox boxWithWidth:1 height:1 
                                      length:1 chamferRadius:0];
        node.position = SCNVector3Make(arc4random_uniform(side) - side / 2.0,
                                       0,
                                       arc4random_uniform(side) - side / 2.0);

        [nodes addObject:node];
    }

    [mySCNView prepareObjects:nodes withCompletionHandler:^(BOOL success) {
        for(SCNNode*node in nodes){
            [scene.rootNode addChildNode:node];
        }
    }];

}

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