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POThread not throwing an InterruptedException when interrupt() is called
 

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  1. POThread not throwing an InterruptedException when interrupt() is called
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    <p>I am working on an application that reads and processes data over a network. While testing the connecting/disconnecting logic of the program I noticed that my consumer thread was not closing when it reached it's closing condition. Below is a stripped out version of the consumer class.</p> <pre><code>import java.io.InputStream; public class Consumer implements Runnable { private final InputStream input; public Consumer(InputStream input) { this.input = input; } @Override public void run() { byte readBuffer[]; readBuffer = new byte[1]; int goodData; try { while(input.available() &gt; 0) { goodData = input.read(readBuffer); while (goodData &gt; 0 ) { System.out.println(readBuffer[0]); if ( readBuffer[0] == 27 ) { System.out.println("Consumer: found closing byte and closing thread "+Thread.currentThread().getName()); //this is the last packet, so interupt thread to close Thread.currentThread().interrupt(); //return; //Thread.currentThread().stop(new InterruptedException("Attempting to close")); } goodData = input.read(readBuffer); } } } catch(Exception e) { System.out.println("closing "+Thread.currentThread().getName() +" because of an exception "+e.getClass()); return; } System.out.println("closing "+Thread.currentThread().getName()); } } </code></pre> <p>I created a dummy main class that demonstrates the problem.</p> <pre><code>public class ExampleOfInterruptNotWorking { public static void main(String[] args) { byte[] bytesToWrite = new byte[]{0, 1, 2,3,4,5,6,65,23,65,21,54,13,54,1,76}; Consumer C; Thread ConsumerThread; PipedInputStream PIS = null; PipedOutputStream POS = null; try { PIS = new PipedInputStream(); POS = new PipedOutputStream(PIS); C = new Consumer(PIS); ConsumerThread = new Thread(C); ConsumerThread.start(); POS.write(bytesToWrite); POS.write(bytesToWrite); bytesToWrite[1] = 27; POS.write(bytesToWrite); ConsumerThread.join(); } catch(Exception e) { System.err.println("Unexpected exception in main"); e.printStackTrace(System.err); } finally { try { PIS.close(); POS.close(); } catch(Exception ex) { //shouldn't happen in example } System.out.println("exiting main"); } } } </code></pre> <p>When you run this code as written, the consumer detects the interrupt, but does not stop execution until the pipe is empty (not what I want). Just to try, I changed to a Thread.stop() call which did what I wanted, but I don't want to leave that in production code. I realized that I could use a simple return statement, but this is not the only point the thread could exit, and I'd like to have some common exit code that cleans up resources. So, my question is, why is the consumer thread not being interrupted? and is there a good way for me to be able to have common exit code?</p> <p>Thanks!</p>
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    1. COIt was not interrupted because it was not waiting and you didn't send it a message. Good way is to close a stream when you finished writing.
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      1. USRoman C
    2. COThe return statement is looking like your best bet. Can you please try to demonstrate the problem where you say you can't create "some common exit code that cleans up resources"? Usually, you do that in a finally block.
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      1. USJohn Watts
    3. CO@RomanC I don't really like closing streams out from under something that is reading them. In this particular case, I am getting a return message to a close connection request. With how the application was designed, I cannot guarantee that the close message is the last one sent out. As it was posted below "Exceptions are for exceptional cases" and closing a stream would cause an IOException - when I would already know the stream was closing.
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      1. USadeady
 

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