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POAndroid parallel (simultaneous) images download
 

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    <p>Guys help please it's important.</p> <p>I need to download about 2000 images in less than 5 minutes. So I decided to make parallel image downloading.</p> <p>If someone can suggest me better way to do parallel downloads or told me where I'm going wrong, I'd really appreciate that.</p> <p>In error log number of completed tasks is always various...</p> <p>Help please.</p> <p>I'm using Async task Executor by Artem Zinnatullin </p> <pre><code>public class AsyncTaskExecutor { private static final int CORE_POOL_SIZE; private static final int MAXIMUM_POOL_SIZE; private static final int KEEP_ALIVE; private static final TimeUnit TIME_UNIT; private static final BlockingQueue&lt;Runnable&gt; concurrentPoolWorkQueue; private static final ThreadFactory concurrentThreadFactory; private static final ThreadPoolExecutor concurrentExecutor; private AsyncTaskExecutor() {} static { CORE_POOL_SIZE = 5; MAXIMUM_POOL_SIZE = 128; KEEP_ALIVE = 1; TIME_UNIT = TimeUnit.SECONDS; concurrentPoolWorkQueue = new LinkedBlockingQueue&lt;Runnable&gt;(10); concurrentThreadFactory = new AsyncTaskThreadFactory(); concurrentExecutor = new ThreadPoolExecutor(CORE_POOL_SIZE,MAXIMUM_POOL_SIZE, KEEP_ALIVE, TIME_UNIT, concurrentPoolWorkQueue, concurrentThreadFactory); } /** * Concurrently executes AsyncTask on any Android version * @param task to execute * @param params for task * @return executing AsyncTask */ @SuppressLint("NewApi") public static &lt;Params, Progress, Result&gt; AsyncTask&lt;Params, Progress, Result&gt; executeConcurrently(AsyncTask&lt;Params, Progress, Result&gt; task, Params... params) { if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.HONEYCOMB) { task.executeOnExecutor(concurrentExecutor, params); } else { task.execute(params); } return task; } /** * Thread factory for AsyncTaskExecutor * @author Artem Zinnatullin * */ private static class AsyncTaskThreadFactory implements ThreadFactory { private final AtomicInteger count; { count = new AtomicInteger(1); } @Override public Thread newThread(Runnable r) { return new Thread(r, "AsyncTask #" + count.getAndIncrement()); } } </code></pre> <p>}</p> <p>Then I'm using loop to download all my images.</p> <pre><code>for (PhotoToDBHelper photoToDBHelper : notDownloaded) { try { photoToDBHelper.download(m_context); } catch (Exception e) { // TODO: handle exception } } </code></pre> <p>where download method look like this:</p> <pre><code>public void download(Context context) throws Exception { HttpClient httpClient = new DefaultHttpClient(); HttpGet httpGet = new HttpGet(new URL(getPhotosUrl() + m_fileName).toString()); HttpResponse response = httpClient.execute(httpGet); HttpEntity entity = response.getEntity(); InputStream inputStream = entity.getContent(); filePath = Environment.getExternalStorageDirectory().toString() + getFoldeRelativePath() + m_fileName; Utils.createFileOnExternalStorage(getFoldeRelativePath(), filePath); FileOutputStream fos = new FileOutputStream(filePath, false); byte[] buffer = new byte[20000]; int byteRead = 0; while ((byteRead = inputStream.read(buffer)) != -1) { fos.write(buffer, 0, byteRead); } fos.close(); } </code></pre> <p>And when start my android application I am getting this error</p> <pre><code>02-25 01:08:30.133: E/AndroidRuntime(32357): FATAL EXCEPTION: main 02-25 01:08:30.133: E/AndroidRuntime(32357): java.lang.RuntimeException: Unable to start activity ComponentInfo{"package".TabHostActivity}: java.util.concurrent.RejectedExecutionException: Task android.os.AsyncTask$3@2c0809b0 rejected from java.util.concurrent.ThreadPoolExecutor@2be18f48[Running, pool size = 128, active threads = 1, queued tasks = 10, completed tasks = 27] 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.ActivityThread.access$600(ActivityThread.java:127) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.os.Handler.dispatchMessage(Handler.java:99) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.os.Looper.loop(Looper.java:137) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.ActivityThread.main(ActivityThread.java:4441) 02-25 01:08:30.133: E/AndroidRuntime(32357): at java.lang.reflect.Method.invokeNative(Native Method) 02-25 01:08:30.133: E/AndroidRuntime(32357): at java.lang.reflect.Method.invoke(Method.java:511) 02-25 01:08:30.133: E/AndroidRuntime(32357): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 02-25 01:08:30.133: E/AndroidRuntime(32357): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 02-25 01:08:30.133: E/AndroidRuntime(32357): at dalvik.system.NativeStart.main(Native Method) 02-25 01:08:30.133: E/AndroidRuntime(32357): Caused by: java.util.concurrent.RejectedExecutionException: Task android.os.AsyncTask$3@2c0809b0 rejected from java.util.concurrent.ThreadPoolExecutor@2be18f48[Running, pool size = 128, active threads = 1, queued tasks = 10, completed tasks = 1032] 02-25 01:08:30.133: E/AndroidRuntime(32357): at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:1967) 02-25 01:08:30.133: E/AndroidRuntime(32357): at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:782) 02-25 01:08:30.133: E/AndroidRuntime(32357): at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1303) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:564) 02-25 01:08:30.133: E/AndroidRuntime(32357): at "package".data.AsyncTaskExecutor.executeConcurrently(AsyncTaskExecutor.java:58) 02-25 01:08:30.133: E/AndroidRuntime(32357): at "package".TabHostActivity.checkUpdateState(TabHostActivity.java:130) 02-25 01:08:30.133: E/AndroidRuntime(32357): at "package".TabHostActivity.onCreate(TabHostActivity.java:88) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.Activity.performCreate(Activity.java:4465) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 02-25 01:08:30.133: E/AndroidRuntime(32357): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931) 02-25 01:08:30.133: E/AndroidRuntime(32357): ... 11 more </code></pre>
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    1. COI am calling AsyncTaskExecutor.executeConcurrently(new DownloadFilesTask(), params), where params is PhotoToDbHelper object, and this loop above is looping at doInBackground of DownloadFilesTask
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    2. CODid you try multithreading?
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