AsyncTask測试多任务-白红宇

AsyncTask測试多任务

阅读量：6119 次

发布时间：2019-06-21

本文共 12638 字，大约阅读时间需要 42 分钟。

本人进行过模拟測试，发现AsyncTask并不适合多任务，以及长期的异步任务，由于每次仅仅能执行一个AsyncTask，假设执行多个其他任务将会等待

以下通过一个代码样例和日志打印得到证实。

以下扩展了2个AsyncTask，分别调用了2次，一共调用了四次。

public class MainActivity extends Activity {	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);		// 4个异步一起运行,2个不同的实现对象		new MyTask().execute("http://www.baidu.com/img/bdlogo.png");		new MyTask2().execute("http://www.baidu.com/img/bdlogo.png");		new MyTask2().execute("http://www.baidu.com/img/bdlogo.png");		new MyTask().execute("http://www.baidu.com/img/bdlogo.png");	}	public class MyTask2 extends AsyncTask
     
       {		public MyTask2() {			super();		}		@Override		protected void onPostExecute(Bitmap result) {			Log.d("MainActivity", "onPostExecute");			updateImageView(result);		}		@Override		protected void onPreExecute() {			Log.d("MainActivity", "onPreExecute");		}		@Override		protected Bitmap doInBackground(String... args) {			Log.e("MainActivity", "MyTask2：" + THREAD_POOL_EXECUTOR); // static对象都一样，运行的线程池																					Log.e("MainActivity", "MyTask2：" + SERIAL_EXECUTOR); // static对象都一样，运行任务的																				String website = args[0];			HttpURLConnection conn = null;			InputStream ins = null;			try {				for (int i = 0; i < 10; i++) {					Thread.sleep((int) (Math.random() * 100 + 800));  
      //有益休眠					Log.d("MainActivity", "MyTask2:" + i + " " + Thread.currentThread().getName() + " id:"							+ Thread.currentThread().getId());				}				URL url = new URL(website);				conn = (HttpURLConnection) url.openConnection();				conn.setConnectTimeout(5000);				conn.setDoInput(true);				if (conn.getResponseCode() == 200) {					Log.d("MainActivity", "MyTask2:" + "get image is ok");					ins = conn.getInputStream();					return BitmapFactory.decodeStream(ins);				}			} catch (MalformedURLException e) {				e.printStackTrace();			} catch (IOException e) {				e.printStackTrace();			} catch (InterruptedException e) {				// TODO Auto-generated catch block				e.printStackTrace();			} finally {				if (ins != null) {					try {						ins.close();					} catch (IOException e) {						e.printStackTrace();					}				}			}			return null;		}	}	public class MyTask extends AsyncTask
      
        {		public MyTask() {			super();		}		@Override		protected void onPostExecute(Bitmap result) {			Log.d("MainActivity", "onPostExecute");			updateImageView(result);		}		@Override		protected void onPreExecute() {			Log.d("MainActivity", "onPreExecute");		}		@Override		protected Bitmap doInBackground(String... args) {			Log.e("MainActivity", "MyTask：" + THREAD_POOL_EXECUTOR);			Log.e("MainActivity", "MyTask：" + SERIAL_EXECUTOR);			for (int i = 0; i < 10; i++) {				try {					Thread.sleep((int) (Math.random() * 100 + 600));//有益休眠				} catch (InterruptedException e) {					e.printStackTrace();				}				Log.d("MainActivity", "MyTask:" + i + " " + Thread.currentThread().getName() + " id:"						+ Thread.currentThread().getId());			}			String website = args[0];			HttpURLConnection conn = null;			InputStream ins = null;			try {				URL url = new URL(website);				conn = (HttpURLConnection) url.openConnection();				conn.setConnectTimeout(5000);				conn.setDoInput(true);				if (conn.getResponseCode() == 200) {					Log.d("MainActivity", "get image is ok");					ins = conn.getInputStream();					return BitmapFactory.decodeStream(ins);				}			} catch (MalformedURLException e) {				e.printStackTrace();			} catch (IOException e) {				e.printStackTrace();			} finally {				if (ins != null) {					try {						ins.close();					} catch (IOException e) {						e.printStackTrace();					}				}			}			return null;		}	}	boolean f = false;	public void updateImageView(Bitmap result) {		if (result != null) {			ImageView img = (ImageView) findViewById(R.id.img);			img.setImageBitmap(result);		}	}}

4个异步执行发现，第一个必须执行完才干执行下一个？仅仅是我理解不正确，还是使用方法有问题，假设有朋友知道请指正。

打印日志例如以下：

12-17 05:24:57.665: D/MainActivity(25755): onPreExecute12-17 05:24:57.665: D/dalvikvm(25755): create interp thread : stack size=32KB12-17 05:24:57.665: D/dalvikvm(25755): create new thread12-17 05:24:57.666: D/dalvikvm(25755): new thread created12-17 05:24:57.666: D/dalvikvm(25755): update thread list12-17 05:24:57.666: D/dalvikvm(25755): threadid=16: interp stack at 0x5e67700012-17 05:24:57.666: D/dalvikvm(25755): threadid=16: created from interp12-17 05:24:57.666: D/dalvikvm(25755): start new thread12-17 05:24:57.666: D/dalvikvm(25755): threadid=16: notify debugger12-17 05:24:57.666: D/dalvikvm(25755): threadid=16 (AsyncTask #5): calling run()12-17 05:24:57.666: D/MainActivity(25755): onPreExecute12-17 05:24:57.666: E/MainActivity(25755): MyTask：java.util.concurrent.ThreadPoolExecutor@42258eb8[Running, pool size = 5, active threads = 1, queued tasks = 0, completed tasks = 4]12-17 05:24:57.666: E/MainActivity(25755): MyTask：android.os.AsyncTask$SerialExecutor@42258fc812-17 05:24:57.669: D/MainActivity(25755): onPreExecute12-17 05:24:57.669: D/MainActivity(25755): onPreExecute12-17 05:24:57.731: V/InputMethodManager(25755): onWindowFocus: null softInputMode=288 first=true flags=#181010012-17 05:24:57.731: V/InputMethodManager(25755): START INPUT: com.android.internal.policy.impl.PhoneWindow$DecorView{422f7c58 V.E..... R.....ID 0,0-1080,1920} ic=null tba=android.view.inputmethod.EditorInfo@422fe938 controlFlags=#10412-17 05:24:57.733: V/InputMethodManager(25755): Starting input: Bind result=InputBindResult{com.android.internal.view.IInputMethodSession$Stub$Proxy@42301bb0 com.android.inputmethod.latin/.LatinIME #609}12-17 05:24:58.281: D/MainActivity(25755): MyTask:0 AsyncTask #5 id:478412-17 05:24:58.966: D/MainActivity(25755): MyTask:1 AsyncTask #5 id:478412-17 05:24:59.643: D/MainActivity(25755): MyTask:2 AsyncTask #5 id:478412-17 05:25:00.276: D/MainActivity(25755): MyTask:3 AsyncTask #5 id:478412-17 05:25:00.946: D/MainActivity(25755): MyTask:4 AsyncTask #5 id:478412-17 05:25:01.589: D/MainActivity(25755): MyTask:5 AsyncTask #5 id:478412-17 05:25:02.224: D/MainActivity(25755): MyTask:6 AsyncTask #5 id:478412-17 05:25:02.842: D/MainActivity(25755): MyTask:7 AsyncTask #5 id:478412-17 05:25:03.464: D/MainActivity(25755): MyTask:8 AsyncTask #5 id:478412-17 05:25:04.120: D/MainActivity(25755): MyTask:9 AsyncTask #5 id:478412-17 05:25:04.123: I/System.out(25755): [CDS]rx timeout:012-17 05:25:04.125: I/System.out(25755): [CDS]close[48692]12-17 05:25:04.126: I/System.out(25755): close [socket][/0.0.0.0:48692]12-17 05:25:04.430: D/libc-netbsd(25755): getaddrinfo: www.baidu.com get result from proxy >>12-17 05:25:04.430: I/System.out(25755): propertyValue:true12-17 05:25:04.431: I/System.out(25755): [socket][1] connection www.baidu.com/180.97.33.107:80;LocalPort=38503(5000)12-17 05:25:04.431: I/System.out(25755): [CDS]connect[www.baidu.com/180.97.33.107:80] tm:512-17 05:25:04.432: D/Posix(25755): [Posix_connect Debug]Process com.example.asynctaskdemo :80 12-17 05:25:04.547: I/System.out(25755): [socket][/192.168.2.122:38503] connected12-17 05:25:04.547: I/System.out(25755): [CDS]rx timeout:012-17 05:25:04.613: D/MainActivity(25755): get image is ok12-17 05:25:04.643: D/dalvikvm(25755): GC_FOR_ALLOC freed 677K (925), 32% free 3736K/5484K, paused 23ms, total 28ms12-17 05:25:04.646: D/skia(25755): Flag is not 1012-17 05:25:04.647: D/MainActivity(25755): onPostExecute12-17 05:25:04.648: E/MainActivity(25755): MyTask2：java.util.concurrent.ThreadPoolExecutor@42258eb8[Running, pool size = 5, active threads = 1, queued tasks = 0, completed tasks = 5]12-17 05:25:04.648: E/MainActivity(25755): MyTask2：android.os.AsyncTask$SerialExecutor@42258fc812-17 05:25:04.668: I/SurfaceTextureClient(25755): [STC::queueBuffer] (this:0x5eee0028) fps:0.14, dur:6910.24, max:6910.24, min:6910.2412-17 05:25:04.668: I/SurfaceTextureClient(25755): [STC::queueBuffer] this:0x5eee0028, api:1, last queue time elapsed:6910.2412-17 05:25:05.485: D/MainActivity(25755): MyTask2:0 AsyncTask #5 id:478412-17 05:25:06.323: D/MainActivity(25755): MyTask2:1 AsyncTask #5 id:478412-17 05:25:07.217: D/MainActivity(25755): MyTask2:2 AsyncTask #5 id:478412-17 05:25:08.107: D/MainActivity(25755): MyTask2:3 AsyncTask #5 id:478412-17 05:25:09.002: D/MainActivity(25755): MyTask2:4 AsyncTask #5 id:478412-17 05:25:09.881: D/MainActivity(25755): MyTask2:5 AsyncTask #5 id:478412-17 05:25:10.771: D/MainActivity(25755): MyTask2:6 AsyncTask #5 id:478412-17 05:25:11.579: D/MainActivity(25755): MyTask2:7 AsyncTask #5 id:478412-17 05:25:12.445: D/MainActivity(25755): MyTask2:8 AsyncTask #5 id:478412-17 05:25:13.299: D/MainActivity(25755): MyTask2:9 AsyncTask #5 id:478412-17 05:25:13.300: I/System.out(25755): [CDS]rx timeout:012-17 05:25:13.586: D/MainActivity(25755): MyTask2:get image is ok12-17 05:25:13.610: D/dalvikvm(25755): GC_FOR_ALLOC freed 688K (1136), 33% free 3689K/5484K, paused 21ms, total 21ms12-17 05:25:13.613: D/skia(25755): Flag is not 1012-17 05:25:13.613: D/MainActivity(25755): onPostExecute12-17 05:25:13.615: E/MainActivity(25755): MyTask2：java.util.concurrent.ThreadPoolExecutor@42258eb8[Running, pool size = 5, active threads = 1, queued tasks = 0, completed tasks = 6]12-17 05:25:13.615: E/MainActivity(25755): MyTask2：android.os.AsyncTask$SerialExecutor@42258fc812-17 05:25:13.630: I/SurfaceTextureClient(25755): [STC::queueBuffer] (this:0x5eee0028) fps:0.11, dur:8961.83, max:8961.83, min:8961.8312-17 05:25:13.630: I/SurfaceTextureClient(25755): [STC::queueBuffer] this:0x5eee0028, api:1, last queue time elapsed:8961.8312-17 05:25:14.455: D/MainActivity(25755): MyTask2:0 AsyncTask #5 id:478412-17 05:25:15.304: D/MainActivity(25755): MyTask2:1 AsyncTask #5 id:478412-17 05:25:16.104: D/MainActivity(25755): MyTask2:2 AsyncTask #5 id:478412-17 05:25:17.008: D/MainActivity(25755): MyTask2:3 AsyncTask #5 id:478412-17 05:25:17.887: D/MainActivity(25755): MyTask2:4 AsyncTask #5 id:478412-17 05:25:18.737: D/MainActivity(25755): MyTask2:5 AsyncTask #5 id:478412-17 05:25:19.584: D/MainActivity(25755): MyTask2:6 AsyncTask #5 id:478412-17 05:25:20.399: D/MainActivity(25755): MyTask2:7 AsyncTask #5 id:478412-17 05:25:21.281: D/MainActivity(25755): MyTask2:8 AsyncTask #5 id:478412-17 05:25:22.130: D/MainActivity(25755): MyTask2:9 AsyncTask #5 id:478412-17 05:25:22.132: I/System.out(25755): [CDS]rx timeout:012-17 05:25:22.178: D/MainActivity(25755): MyTask2:get image is ok12-17 05:25:22.202: D/dalvikvm(25755): GC_FOR_ALLOC freed 641K (300), 33% free 3689K/5484K, paused 21ms, total 22ms12-17 05:25:22.208: D/skia(25755): Flag is not 1012-17 05:25:22.209: D/MainActivity(25755): onPostExecute12-17 05:25:22.211: E/MainActivity(25755): MyTask：java.util.concurrent.ThreadPoolExecutor@42258eb8[Running, pool size = 5, active threads = 1, queued tasks = 0, completed tasks = 7]12-17 05:25:22.211: E/MainActivity(25755): MyTask：android.os.AsyncTask$SerialExecutor@42258fc812-17 05:25:22.219: I/SurfaceTextureClient(25755): [STC::queueBuffer] (this:0x5eee0028) fps:0.12, dur:8589.36, max:8589.36, min:8589.3612-17 05:25:22.219: I/SurfaceTextureClient(25755): [STC::queueBuffer] this:0x5eee0028, api:1, last queue time elapsed:8589.3612-17 05:25:22.839: D/MainActivity(25755): MyTask:0 AsyncTask #5 id:478412-17 05:25:23.519: D/MainActivity(25755): MyTask:1 AsyncTask #5 id:478412-17 05:25:24.176: D/MainActivity(25755): MyTask:2 AsyncTask #5 id:478412-17 05:25:24.786: D/MainActivity(25755): MyTask:3 AsyncTask #5 id:478412-17 05:25:25.440: D/MainActivity(25755): MyTask:4 AsyncTask #5 id:478412-17 05:25:26.134: D/MainActivity(25755): MyTask:5 AsyncTask #5 id:478412-17 05:25:26.740: D/MainActivity(25755): MyTask:6 AsyncTask #5 id:478412-17 05:25:27.367: D/MainActivity(25755): MyTask:7 AsyncTask #5 id:478412-17 05:25:27.988: D/MainActivity(25755): MyTask:8 AsyncTask #5 id:478412-17 05:25:28.617: D/MainActivity(25755): MyTask:9 AsyncTask #5 id:478412-17 05:25:28.618: I/System.out(25755): [CDS]rx timeout:012-17 05:25:28.658: D/MainActivity(25755): get image is ok12-17 05:25:28.681: D/dalvikvm(25755): GC_FOR_ALLOC freed 641K (299), 33% free 3689K/5484K, paused 20ms, total 21ms12-17 05:25:28.683: D/skia(25755): Flag is not 1012-17 05:25:28.684: D/MainActivity(25755): onPostExecute12-17 05:25:28.694: I/SurfaceTextureClient(25755): [STC::queueBuffer] (this:0x5eee0028) fps:0.15, dur:6474.71, max:6474.71, min:6474.7112-17 05:25:28.694: I/SurfaceTextureClient(25755): [STC::queueBuffer] this:0x5eee0028, api:1, last queue time elapsed:6474.71

发现ThreadPool每次仅仅有1个线程在执行，一个时刻仅仅能执行一次。上面执行的情况是线程被反复利用了，

手机上执行线程NAME和ID都是一样，在模拟器上执行ID和NAME即便是不一样也是顺序执行的，并没有同一时候执行多个任务的情况发现。

个人经过測试发现，AsyncTask 仅仅能用一次，假设实例化多个AsyncTask 并不能提高执行效率，不能利用多任务的情况。不知道是不是这样，google设计这个AsyncTask的目的仅仅是用来执行一次异步任务，和UI更新？如有朋友知道详细理由请指出,，谢谢。

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