多少AsyncTasks我可以在单个进程中运行的应用程序 [英] How many AsyncTasks i can run in an single process application

问题描述

我使用asyncTasks，用来加载图像列表元素（只是跟着Android的有效装载位图的教程）

I am using asyncTasks, to load list elements with images (Just followed android's tutorial of efficiently loading bitmaps)

在DDMS，我可以看到高达5 As​​yncTasks是运行

In DDMS, i can see upto 5 AsyncTasks being running

现在除了我已经增加了一个AsyncTask的，使用Media codeC类执行一些解码。

Now in addition i have added another AsyncTask, which performs some decoding using MediaCodec class.

现在在DDMS，我仍然看到5 AsyncTasks，我的图像加载aynctask或解码异步执行任务，而不是他们两个。

Now in DDMS, i still see 5 AsyncTasks, and my image loading aynctask or decoding async task executes, not both of them.

在解码运行时，如果我滚动列表，也不会更新元素的图像
Counterly当我通过调用它的执行方法，推出新的解码的AsyncTask，解码不会启动，但如果我现在滚动列表视图，图像更新。

When decoding is running, if i scroll the list, elements' images are not updated Counterly when i launch new decoding asynctask by calling it's execute method, the decoding doesn't start, but if i scroll the list view now, the images are updated.

原来是AsyncTask的是limitted ??

So is AsyncTask is limitted??

即使在listAdapter我每次推出电话getView的AsyncTask的。我已经期待7运行asyncTasks（如果列表中可见元素是7，说），但DDMS只显示5运行asynctasks。

Even in listAdapter i launch an AsyncTask per getView call. I'd expecting 7 running asyncTasks (if list visible elements are 7, say), but DDMS shows only 5 asynctasks running.

现在能有人解释我有什么魔法，我不能拼？

Now can someone explain me what's the black magic that i can't spell?

推荐答案

多少 AsyncTasks 你可以同时运行？

How many AsyncTasks can you run at once?

在Android的大多数版本，答案是的 128

In most versions of Android, the answer is 128.

为什么你通常​​清楚地看到5 的AsyncTask 主题？

Why will you generally see exactly 5 AsyncTask threads?

的AsyncTask 线程管理相当混乱，尤其是自从第一款Android版本已经改变了很多。

AsyncTask thread management is rather confusing, especially since it has changed a lot since the first Android release.

在新的Andr​​oid版本中，5个线程，默认情况下创建和的ThreadPoolExecutor 将尝试运行的AsyncTask S于这5个线程。如果您创建超过5 的AsyncTask S，它既可排队它们或创建新的线程（但最多只能到128）。

In newer Android versions, 5 threads are create by default, and the ThreadPoolExecutor will attempt to run the AsyncTasks on these 5 threads. If you create more than 5 AsyncTasks, it may either queue them or create new threads (but only up to 128).

请注意，在早期版本的Andr​​oid，这些限不同。我相信，原来，有永远只能有一个线程创建了。

Note that in earlier versions of Android, these limits were differently. I believe that, originally, there was only ever one thread created.

但是，所有的图像最终应加载...

要回答你的问题的另一部分，除非你加载大量的图片（其中很多是指> 128），所有的图像应加载，但可能顺序。如果第5负荷，其余不这样做，这可能表明你的 doInBackground（）函数永远不会完成或者有别的毛病 AsyncTask的您使用。

To answer the other part of your question, unless you're loading a lot of images (where a lot means >128), all the images should load, although likely sequentially. If the first 5 load and the rest do not, that might indicate that your doInBackground() function is never finishing or there is something else wrong with the AsyncTask you are using.

资源：

下面是学习更多有关的AsyncTask 线程管理一些有用的资源：

Here are some helpful resources for learning more about AsyncTask thread management:

AsyncTask的线程永远不死（Android版）

的Andr​​oid的AsyncTask线程限制？

<一个href=\"http://stackoverflow.com/questions/9593850/is-there-a-limit-of-asynctasks-to-be-executed-at-the-same-time\">Is有AsyncTasks的限制的同时被执行？

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