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PONew Task is not being picked up by a thread once it is done with the first one and goes in wait state for forever
 

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  1. PONew Task is not being picked up by a thread once it is done with the first one and goes in wait state for forever
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    <p>Sample code:</p> <pre><code>public class ThreadTest{ public static void main(String ...arg){ try{ ExecutorService executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors()); for(int i=0; i &lt; noOfTask; i++){ executor.execute(new ImplRunnable(connectionPool.getConnection())); } executor.shutdown(); //Wait for all threads completion executor.awaitTermination(100, TimeUnit.MICROSECONDS); }catch(Exception e){ e.printStackTrace(); }finally{ //close database connections etc. } } } class ImplRunnable implements Runnable{ private Connection conn; public ImplRunnable(Connection conn){ this.conn = conn; } public void run(){ try{ for(int i =0; i &lt; 1000000; i++){ counts++; } }catch(Exception exception){ exception.printStackTrace(); }finally{ //close all open statements try{ conn.close(); }catch(Exception exp){ exp.printStackTrace(); } } } } </code></pre> <p>My system has 4 cores therefore the pool size is 4 and I have 10 tasks to do</p> <p>The for loop is opening 10 threads but 4 threads are running at a time. But the problem is when a thread is completed processing it is going in waiting state for forever and not picking up next task for processing. What is wrong with the above code?</p> <p>Please suggest...</p>
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    1. This table or related slice is empty.
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    1. USPahari Chora
    1. USPahari Chora
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    1. CODoes replacing `while (!executor.isTerminated()) {}` with `executor.awaitTermination(60, TimeUnit.SECONDS)` help? Also your code does not compile (missing `Runnable` implementation). Finally the loop is not opening 10 threads, it submits 10 tasks to the pool, having 4 threads (so 6 will queue up). Besides your code is fine.
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      1. PONew Task is not being picked up by a thread once it is done with the first one and goes in wait state for forever
      1. USTomasz Nurkiewicz
    2. CO@TomaszNurkiewicz thx for your response. I do have impl class for Runnable.. This is just sample code... I will try whatever you have mentioned above.
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      1. PONew Task is not being picked up by a thread once it is done with the first one and goes in wait state for forever
      1. USPahari Chora
    3. COhey @TomaszNurkiewicz it looks like executor.awaitTermination(60, TimeUnit.SECONDS) is faster than while (!executor.isTerminated()) {}.. why is it? any thoughts?
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      1. PONew Task is not being picked up by a thread once it is done with the first one and goes in wait state for forever
      1. USPahari Chora
 

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