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POfuture.isDone returns false even if the task is done
 

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    <p>I have tricky situation, Does <code>future.isDone()</code> returns <code>false</code>, even if the thread is done.</p> <pre><code>import java.util.ArrayList; import java.util.LinkedList; import java.util.List; import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.Callable; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutionException; import java.util.concurrent.Future; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; public class DataAccessor { private static ThreadPoolExecutor executor; private int timeout = 100000; static { executor = new ThreadPoolExecutor(10, 10, 1000, TimeUnit.SECONDS, new ArrayBlockingQueue&lt;Runnable&gt;(1000)); } public static void main(String[] args) { List&lt;String&gt; requests = new ArrayList&lt;String&gt;(); for(int i=0; i&lt;20; i++){ requests.add("request:"+i); } DataAccessor dataAccessor = new DataAccessor(); List&lt;ProcessedResponse&gt; results = dataAccessor.getDataFromService(requests); for(ProcessedResponse response:results){ System.out.println("response"+response.toString()+"\n"); } executor.shutdown(); } public List&lt;ProcessedResponse&gt; getDataFromService(List&lt;String&gt; requests) { final CountDownLatch latch = new CountDownLatch(requests.size()); List&lt;SubmittedJob&gt; submittedJobs = new ArrayList&lt;SubmittedJob&gt;(requests.size()); for (String request : requests) { Future&lt;ProcessedResponse&gt; future = executor.submit(new GetAndProcessResponse(request, latch)); submittedJobs.add(new SubmittedJob(future, request)); } try { if (!latch.await(timeout, TimeUnit.MILLISECONDS)) { // some of the jobs not done System.out.println("some jobs not done"); } } catch (InterruptedException e1) { // take care, or cleanup for (SubmittedJob job : submittedJobs) { job.getFuture().cancel(true); } } List&lt;ProcessedResponse&gt; results = new LinkedList&lt;DataAccessor.ProcessedResponse&gt;(); for (SubmittedJob job : submittedJobs) { try { // before doing a get you may check if it is done if (!job.getFuture().isDone()) { // cancel job and continue with others job.getFuture().cancel(true); continue; } ProcessedResponse response = job.getFuture().get(); results.add(response); } catch (ExecutionException cause) { // exceptions occurred during execution, in any } catch (InterruptedException e) { // take care } } return results; } private class SubmittedJob { final String request; final Future&lt;ProcessedResponse&gt; future; public Future&lt;ProcessedResponse&gt; getFuture() { return future; } public String getRequest() { return request; } SubmittedJob(final Future&lt;ProcessedResponse&gt; job, final String request) { this.future = job; this.request = request; } } private class ProcessedResponse { private final String request; private final String response; ProcessedResponse(final String request, final String response) { this.request = request; this.response = response; } public String getRequest() { return request; } public String getResponse() { return response; } public String toString(){ return "[request:"+request+","+"response:"+ response+"]"; } } private class GetAndProcessResponse implements Callable&lt;ProcessedResponse&gt; { private final String request; private final CountDownLatch countDownLatch; GetAndProcessResponse(final String request, final CountDownLatch countDownLatch) { this.request = request; this.countDownLatch = countDownLatch; } public ProcessedResponse call() { try { return getAndProcessResponse(this.request); } finally { countDownLatch.countDown(); } } private ProcessedResponse getAndProcessResponse(final String request) { // do the service call // ........ if("request:16".equals(request)){ throw (new RuntimeException("runtime")); } return (new ProcessedResponse(request, "response.of." + request)); } } } </code></pre> <p>if I call <code>future.isDone()</code> it returns <code>false</code> though the <code>coundownLatch.await()</code> return true. Any Idea? Also to note that the countDownLatch.await comes out immediately when this happens.</p> <p>If you are finding the format not readable view here, <a href="http://tinyurl.com/7j6cvep" rel="nofollow">http://tinyurl.com/7j6cvep</a> .</p>
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    1. COYour code doesn't make sense. `pooledExecutor.submit(LCallable)` doesn't work, where do you instantiate the `Callable`? Where do you create the latch, and where do you wait for it?
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    2. CO@skaffman edited the code
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    3. COMy suspicion is that the callables may throw an uncaught exception which consequently aborts the worker threads, however also count down the latch before exiting from `call`.
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      1. USPéter Török
 

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