简单的线程管理 - Java - Android [英] Simple Thread Management - Java - Android
问题描述
我有一个应用程序，当用户要求过滤图像时会产生一个新线程。
I have an application which spawns a new thread when a user asks for an image to be filtered.
这是我拥有的唯一任务类型同样重要。
This is the only type of task that I have and all are of equal importance.
如果我要求太多并发线程（我想要的最大值是9），线程管理器会抛出 RejectedExecutionException 。
If I ask for too many concurrent threads (Max I ever want is 9) the thread manager throws a RejectedExecutionException.
我做的那一刻是;
// Manage Concurrent Tasks
private Queue<AsyncTask<Bitmap,Integer,Integer>> tasks = new LinkedList<AsyncTask<Bitmap,Integer,Integer>>();
@Override
public int remainingSize() {
return tasks.size();
}
@Override
public void addTask(AsyncTask<Bitmap, Integer, Integer> task) {
try{
task.execute(currentThumbnail);
while(!tasks.isEmpty()){
task = tasks.remove();
task.execute(currentThumbnail);
}
} catch (RejectedExecutionException r){
Log.i(TAG,"Caught RejectedExecutionException Exception - Adding task to Queue");
tasks.add(task);
}
}
只需将被拒绝的任务添加到队列中即可一个线程启动的时间，检查队列是否有积压。
Simply add the rejected task to a queue and the next time a thread is started the queue is checked to see if there's a backlog.
这个问题的一个明显问题是，如果最终任务在第一次尝试时被拒绝，它将会永远不会重新启动（直到它不再需要）。
The obvious issue with this is that if the final task gets rejected on its first attempt it will never be restarted (Until after it's no longer needed).
只是想知道我是否应该使用一个简单的模型来管理这类事情。我需要任务在完成后通知队列所以我知道有空间但是我不确定如何。
Just wondering if there's a simple model I should use for managing this sort of thing. I need tasks to notify the queue when they're done so I know there's space but I'm not sure how.
亲切的问候，
Gavin
推荐答案
RejectedExecutionException的原因是因为 AsyncTask 实现了一个自己的线程池（根据Martelli先生的回答），但最多可以同时执行10个任务。为什么他们有这个限制，我不知道。
The reason for the RejectedExecutionException is because AsyncTask implements a thread pool of its own (per Mr. Martelli's answer), but one that is capped at a maximum of 10 simultaneous tasks. Why they have that limit, I have no idea.
因此，有一种可能性是克隆 AsyncTask ，提高限制（或无限制，这也可以通过 LinkedBlockingQueue ），并使用你的克隆。然后，也许，将更改作为补丁提交给 AsyncTask 以用于将来的Android版本。
Hence, one possibility is for you to clone AsyncTask, raise the limit (or go unbounded, which is also possible with LinkedBlockingQueue), and use your clone. Then, perhaps, submit the change as a patch to AsyncTask for future Android releases.
点击此处运行Google代码搜索 AsyncTask - 第一次点击应该是实现。
Click here to run a Google Code Search for AsyncTask -- the first hit should be the implementation.
如果你只是想提高限额，请调整 MAXIMUM_POOL_SIZE 要像你可能需要的一样大。如果您想要无限制，请使用零参数 LinkedBlockingQueue 构造函数，而不是当前使用的构造函数。 AFAICT，其余代码可能保持不变。
If you just want to raise the limit, adjust MAXIMUM_POOL_SIZE to be as big as you're likely to need. If you want to go unbounded, use the zero-argument LinkedBlockingQueue constructor instead of the one being presently used. AFAICT, the rest of the code probably stays the same.
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