AsyncTask 线程永远不会死

我使用 AsyncTask来获取用户按下按钮时的响应数据。这种方法运行良好，并且在获取数据时保持接口响应，但是当我检查 Eclipse 调试器中发生了什么时，我发现每次创建一个新的 AsyncTask(这种情况很常见，因为它们只能使用一次) ，都会创建一个新的线程，但是从未终止。

结果就是大量的 AsyncTask线程只是停留在那里。我不确定这在实践中是否是一个问题，但我真的想摆脱这些额外的线程。

我怎样才能杀死这些线？

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最佳答案

AsyncTask manages a thread pool, created with ThreadPoolExecutor. It will have from 5 to 128 threads. If there are more than 5 threads, those extra threads will stick around for at most 10 seconds before being removed. (note: these figures are for the presently-visible open source code and vary by Android release).

Leave the AsyncTask threads alone, please.

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In addition to CommonsWare's response:

Currently I'm using Android 2.2, and my application uses no more than one AsyncTask at any time, but I'm creating a new one every x minutes. At first new AsyncTask Threads start to appear (a new Thread for a new AsyncTask) but after 5 threads (as mentioned by CommonsWare) they just stay visible in the debug window, and get re-used when new AsyncTask threads are needed. They just stay there until the debugger disconnects.

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Same symptom here. In my case the threads hanged around after I'd killed the Activity, and I was hoping for the App to close completely. Problem partly solved by using a single threaded executor:

    myActiveTask.executeOnExecutor(Executors.newSingleThreadExecutor());

This made the thread to vanish after the completing its work.

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Use ThreadPoolExecutor.

BlockingQueue workQueue= new LinkedBlockingQueue<Runnable>(100); // Work pool size
ThreadPoolExecutor executor = new ThreadPoolExecutor(
Runtime.getRuntime().availableProcessors(),       // Initial pool size
Runtime.getRuntime().availableProcessors(),       // Max pool size
1, // KEEP_ALIVE_TIME
TimeUnit.SECONDS, //  KEEP_ALIVE_TIME_UNIT
workQueue);

Post your Runnable task by using execute() method.

void execute (Runnable command)

Executes the given task sometime in the future. The task may execute in a new thread or in an existing pooled thread

Regarding your second query:

How can I kill these threads?

Once you are done with all your work with ThreadPoolExecutor, shutdown it properly as quoted in below post:

How to properly shutdown java ExecutorService


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