DatagramSocket.receive() and Thread.interrupt() - Inconsistent behavior

Question

Hi,
I currently have an application that does in a seperate Thread receive udp packets in a loop around a Datagramsocket.receive(). Whenever a state change should occur, the thread is being interrupted by Thread.interrupt() in order to exit the DatagramSocket.receive().
That works nicely on the solaris version of the jvm (1.5.0-11) on x86 and sparc but it does not work on linux intel (i386 and amd64). There the receive simply ignores the interrupt.
What is the intended behavior ?
Do I have to move to timeOuts on each receive (which hinders fast state changes as timeouts have to occur and the loop has to be timeouted very often in order to be fast).
Little tests say: (java 1.5)
Linux 2.6.18 (32/64 Bit) : no interrupt
FreeBsd (32/64 Bit): interrupt works
Solaris 10 (sparc/64x86): interrupt works
MacOs 10.4: no interrupt
On Linux 2.6.18, java 1.4 - interrupt works.
At least a consistent behavior is missing!
J�rn
Here is the code:
SubThread.java:
package test;
import java.net.*;
import java.io.*;
public class SubThread extends Thread {
     public DatagramSocket ds;
     public boolean quit=false;
     public SubThread() {
          super();
          try {
               ds = new DatagramSocket();
          } catch (Exception E) {
               System.out.println("new DS failed: "+E.getMessage());
               System.exit(-1);
     public void run() {
          byte[] buf = new byte[1000];
          DatagramPacket p = new DatagramPacket(buf, buf.length);
          System.out.println("Started subThread !");
          while (!quit) {
               try {
                    ds.setSoTimeout(10000); // 10 Seconds
                    ds.receive(p);
               } catch (SocketTimeoutException E) {
                    System.out.println("ST: Hit timeout !");
               } catch (InterruptedIOException E) {
                    System.out.println("ST: Interrupted IO Works !: "+E.getMessage());
                    quit=true;
               } catch (Exception E) {
                    System.out.println("ST: Exception: "+E.getMessage());
          System.out.println("Ended subThread !");
}Test.java:
package test;
public class Test {
     static Integer a = 1;
     public static void main(String[] args) {
          SubThread st = new SubThread();
          st.start();
          try {
               synchronized (a) {
                    System.out.println("Starting wait (1s) !");
                    a.wait(1000);
                    System.out.println("Sending interrupt()");
                    st.interrupt();
                    a.wait(1000);
                    if (!st.quit) {
                         System.out.println("As interrupts do not work, terminating by timeout !");
                         st.quit=true;
                         System.out.println("Waiting for end!");
                    } else
                         System.out.println("Ending !");
          } catch (Exception E) {
               System.out.println("Exception: "+E.getMessage());
}

Answer 1

What is the intended behavior ?The intended behaviour is defined in http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()
' If this thread is blocked in an I/O operation upon an interruptible channel then the channel will be closed, the thread's interrupt status will be set, and the thread will receive a ClosedByInterruptException.'
DatagramSocket not being an InterruptibleChannel, this piece doesn't apply. None of the other pieces apply either, so the fallback applies:
' If none of the previous conditions hold then this thread's interrupt status will be set.'
If you're getting an interrupted read() on one platform, that's a bonus, but it's not the defined behaviour.
Use a DatagramSocket derived from DatagramChannel.open().socket() and it should work on all platforms.