I am attempting to cancel a running process that is reading data
coming in via a socket from an external (non-Java) application.  The
cancel *does* work, except I always get an exception.  Here is the
code in question...

   private void process() throws ProcessException {
       socketWriter.println("START PROCESSING");

       try {
           File outFile = new File(workingFolder, "output.txt");
           FileWriter fw = new FileWriter(outFile, false);
           BufferedWriter bw = new BufferedWriter(fw);

           String line = socketReader.readLine();
           while
(line.indexOf(NativeProcessDistributed.COMPLETED_RUN) == -1) {
               bw.write(line);
               bw.newLine();
               line = socketReader.readLine();
           }

           bw.flush();
       } catch (IOException e) {
           throw new
ProcessException(NativeProcess.CANT_WRITE_OUTPUT);
       }
   }

Basically, I start the processing (via START PROCESSING written to the
application) and then watch the input for a string that means the run
has completed.  Until then, I write out all output to an output file
(so someone can examine the output if anything goes wrong with the
processing).

I want the user to cancel the run at any time in the GUI via a cancel
button.  This is the method that's fired when the cancel button is
pressed

   public void cancel() {
       try {
           // write a suicide file/flag to force the processing to
halt
           File suicide = new File(runFolder + SUICIDE_FILE);
           suicide.createNewFile();

           this.cleanup();

           status = CANCELLED;
           stateChanged();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }

The cleanup() method is as follows:

   private void cleanup() {
       try {
           socketReader.close();
           socketWriter.close();
           clientSocket.close();
           nativeProcess.destroy();
       } catch (IOException e) {
       }
   }

What's happening (as far as I can tell) is that I'm closing the
clientSocket while the "while" loop in the process() method is still
looping, thus causing the exception to be thrown.  I am not sure how
to sync the two methods up so that I can cancel the process AND the
while loop in the distribute method stops (the socketReader.readLine()
is what is throwing the actual exception, BTW).  It may be a threading
issue, but I'm having difficulty figuring out what the issue actually
is.

Thanks for any help with this frustrating problem.