Name: saf@russia Date: 09/06/96


This bug was found by St.Petersburg Java SQE team (by Stanislav Avzan).

The java.io.PipedInputStream.read() method does not work according to
the Java language specification when writer thread is no longer alive.

The Java Language specification
(Version 1.0 - August 1, 1996)
says the following (please see item 22.5.4):

"22.5.4 public int read() throws IOException

If a thread was providing data bytes to the connected piped output
stream, but the thread is no longer alive, then an IOException is thrown.

Implements the read method of InputStream (p.22.3.1)."

So this method should throw IOException
if writer thread is no longer alive.
But in fact it does not.
 
Here is the test demonstrating the bug:
    

----- test6.java ---------------------------------------
import java.io.*;

public class test6 {

  public static void main( String[] argv ) {
    PipedOutputStream os = new PipedOutputStream();
    PipedInputStream is= new PipedInputStream();
    Producer p;
    int rl;
    try {
      is.connect(os);
     } catch(Throwable e) {
       System.out.println("Test failed: unexpected <"+e+"> thrown");
       System.exit(1);
     }
    byte[] data = new byte[1000], comp = new byte[1000]; // create two arrays of bytes
    try {
       p = new Producer(data,os,"Test");// create Producer thread using this array
      p.start();// start producing bytes of data
      try {
        Thread.sleep(1000); // sleep for 1 second
      } catch (InterruptedException e) {}
      p.stop(); //step stop producer thread
      System.out.println("Is producer alive? - "+p.isAlive());
      rl = is.read(comp,0,1000); // read into array of bytes
      System.out.println("Test failed: no exceptions thrown");
    }
    catch(IOException e) // test IOException is thrown
    { System.out.println("Test passed: IOException thrown");
    } catch(Throwable e) {
      System.out.println("Test failed: unexpected <"+e+"> thrown");
    }
  }
}
------- Producer.java ---------------------------------
import java.io.*;

class Producer extends Thread {
  private byte[] data;
  private PipedOutputStream src;
  private String testid;
  private int delay;

  public Producer(byte[] data, PipedOutputStream src, String testid) {
    this.data = data;
    this.src = src;
    this.testid = testid;
    this.delay = 0;
  }
  
  public Producer(byte[] data, PipedOutputStream src, String testid, int delay) {
    this.data = data;
    this.src = src;
    this.testid = testid;
    this.delay = delay;
  }

  public void run() {
    for (int i=0; i < data.length; i++)
      try {
        if (delay > 0)
          try {
            Thread.sleep(delay);
          } catch (InterruptedException e) {}
        src.write(data[i]);
      } catch (IOException e) {
        System.out.println(testid + " failed: PipedOutputStream write error");
        System.exit(1);
      }
    try {
      if (delay > 0)
        try {
          Thread.sleep(delay);
        } catch (InterruptedException e) {}
      src.close();
      sleep(10000); // to allow reader read all written
    } catch(InterruptedException e) {
      } catch (IOException e) {
        System.out.println(testid + " failed: PipedOutputStream close error");
        System.exit(1);
      }
  }

}

----- The output of the test: -------------------------

$JAVA test6
Is producer alive? - false
Test failed: no exceptions thrown

-------------------------------------------------------


Workaround:
None
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